Title of Invention	"METHOD AND DEVICE FOR TRANSMITTING INFORMATION THROUGH A POWER DISTRIBUTION NETWORK"
Abstract	A method for transmitting a piece of information through an electricity distribution network (3) carrying a voltage (Uac), comprising the steps of: connecting, between two wires of the network, an electric element (1, 31) in series with a switch means (2, 32), applying to the switch means a control signal (CS) of determined shape so that the switch means is closed and opened successively, detecting the spurious pulses that appear in the network when the switch means is closed or open, each spurious pulse comprising a high frequency wave train, and reconstituting the control signal (CS).

Title of Invention

"METHOD AND DEVICE FOR TRANSMITTING INFORMATION THROUGH A POWER DISTRIBUTION NETWORK"

Abstract

A method for transmitting a piece of information through an electricity distribution network (3) carrying a voltage (Uac), comprising the steps of: connecting, between two wires of the network, an electric element (1, 31) in series with a switch means (2, 32), applying to the switch means a control signal (CS) of determined shape so that the switch means is closed and opened successively, detecting the spurious pulses that appear in the network when the switch means is closed or open, each spurious pulse comprising a high frequency wave train, and reconstituting the control signal (CS).

Full Text	The present invention relates to a method and a device for transmitting a piece of information through, an electricity distribution network. The electric line has been used for many years as a low-rate data transmission means, particularly in home automation applications, to remotely control electric appliances (such as electric shutters for example). The known data transmission methods involve injecting, into the network, a carrier signal which is modulated appropriately to carry, data. The disadvantage of these methods is that they require the injection of such a carrier signal. They are therefore intrusive and cause interference, and are complex to implement. The present invention aims to provide a method for transmitting a piece of information via an electricity distribution network which is less intrusive and causes less interference than the known methods. The intended applications are mainly the transmission of binary data but also the transmission of a non- binary piece of information, for example a series of pulses having a predetermined profile enabling an electric appliance to be identified without requiring the information to be rebuilt in binary form. As set forth in the patent EP 1 136 829, any electric appliance or element, particularly motors, pumps, transformers, electric bulbs, electric or electronic circuits, generates, when switched on and switched off, a high frequency spurious signal having an electromagnetic origin. As this signal is very short in duration, it forms a high frequency spurious pulse naturally emitted by the electric element. Such a spurious pulse forms a sort of unique signature that is representative of the electric appliance and of its location on the electricity distribution network. Thus, the patent EP 1 136 829 suggests detecting and analyzing the high frequency pulses emitted an the network by electric appliances, so as to identify the appliances that are switched on or switched off. The aforementioned patent also suggests providing a pulse synthesizer capable of supplying a pulse that replaces the spurious pulse naturally emitted when the amplitude of the latter is too low to be validly detected. The use of a pulse synthesizer is also considered to emit a series of pulses comprising a determined number of pulses forming a unique signature. Classically, a pulse synthesizer capable of emitting a series of pulses comprises for example a HF pulse generator switch, a HF oscillator, a logic circuit and an output transformer. The HF oscillator supplies a high frequency signal for switching the HF switch. The logic circuit supplies a coded signal that is mixed with the switching signal to obtain a signal for controlling the switch. The output transformer enables the series of HF pulses artificially reconstituted to be re- injected into the electricity distribution network. However, the cost price and overall dimension of such a pulse synthesizer are substantial in the context of the intended applications, which concern mass markets and demand very low cost prices. Thus, the present invention provides for transmitting a piece of information on an electricity distribution network without using any pulse synthesizer. More particularly, the present invention provides for transmitting a piece of information by using the high frequency spurious pulses naturally emitted by an electric element when the latter is connected or disconnected from the network. For this purpose, the electric element is linked to the network by a switch and the switch is driven by a control signal representative of the information to be transmitted. Thus, the high frequency spurious pulses emitted by the electric element mirror the control signal that itself mirrors the information to be transmitted. The duration of such pulses, of electromagnetic origin, is very short and is independent of the time elapsing between the closing and opening of the switch, which can be much longer. In prior art, various data transmission methods have already been proposed based on the emission of pulses in an electricity distribution network. These are generally voltage or current pulses generated by the discharge of a capacitor, the duration of the discharge forming the duration of the pulse. These voltage or current pulses are directly injected into the network by means of a switch or are injected by inductive coupling. To be detected, they require considerable electrical energy to be injected into the network. With the present invention, the electrical energy that must be applied to the network can, on the contrary, be very low or even almost zero (within the limit of the laws of physics and inductive phenomena) as it is not an energy-carrier voltage or current pulse that is detected, but a high frequency spurious pulse that goes with the connection or the disconnection of the electric element. In prior art, high frequency spurious pulses are perhaps unintentionally emitted simultaneously with the emission of voltage or current pulses, but such spurious pulses emitted unintentionally are not used as a means for transmitting information and are not therefore detected as such. Thus, the document GB 1 153 908 describes a data transmission method consisting in discharging a capacitor 4 in the electric network (Cf. page 2 lines 55-121, Figures 1 to 3) and in detecting the discharge pulses which are superimposed on the alternating voltage of the network. The document US 4 090 184 also describes a data transmission method by discharging a capacitor (Cf. column 17 lines 22-34) and detecting the discharge pulses. The document US 5 614 8 11 also describes a data transmission method by discharging a capacitor (Cf. claim 1, last line). Moreover, this method interferes with the electric network since the capacitor is discharged at moments when the alternating voltage crosses zero (Cf. Fig. 7, column 3 line 61 to column 4 line 16). The document GB 2__P08 299 also describes a data transmission method by discharging a capacitor 20 (Cf. claim 1, last line, Figure 1) . Also in this method, the capacitor can be discharged at moments when the wave of the alternating voltage crosses 0 (Cf. Fig. 18, "signal pulses at zero crossing") . The document US 5 486 805 also describes a method comprising the emission of pulses by discharging a capacitor when the alternating voltage crosses zero (Cf. Figure 1). The document US 2003/0156014 describes a method for transmitting data an an electric network using a plurality of sub- carrier frequencies (Cf. paragraph Oil) that are injected into the network by means of a coupling circuit (Cf. 121, Fig. 3). The document US 2002/0024423 describes a method of injecting coded data on an electric network by means of a pseudo-noised code which is modulated by means of a train of electrical energy pulses without using any sinusoidal carrier. Like the previous ones, this method is based on injecting energy into the electric network and not on the use of natural spurious pulses. The document US 3 714 451 also describes the injection of energy pulses into an electric network, by discharging a capacitor (Cf. 25a Figure 2, Figures 4, 5, 7, claim 1). The document wo 00 /26679 describes a method for detecting the closing of a switch in which current peaks are injected into a branch of a network (Cf. Figure 4) controlled by the switch. The current is injected by a circuit (Cf. Figures 1A or 1B) which cyclically discharges a capacitor (Cf. 170 or 260) . The current pulses are short in duration so as to limit the appearance, in neighboring network branches, of induced current peaks. Therefore, the induced current peaks are of low amplitude and do not interfere with the detection of the main current peak. The main current peak is detected by a detector (Cf. Fig. 2) which comprises a coil (L1) enabling the current peak to be detected by induction. An amplifier coupled to the coil electrically supplies an audible alarm (351) which emits an audible signal when the user approaches the branch in which the current peaks are injected. Finally, the document US 4 982 175 describes a telemetry system that injects pulses on an electric network (Cf. 32, Figure 3) caused by the discharge of a capacitor (Cf. 26, Figure 2). These pulses are not high frequency spurious pulses within the meaning of the present invention and are detected by induction by means of coils (Cf. 41a to 42b, Figure 6) . "Thus, the present invention provides a method for transmitting a piece of information through an electricity distribution network carrying a voltage, comprising the following steps of: linking an electric element to the network through a switch means, the electric element naturally emitting a high frequency spurious pulse when it is connected to the network by the closing of the switch means and/or when it is disconnected from the network by the opening of the switch means, applying to the switch means a control signal of determined shape so that the electric element emits a predetermined series of high frequency spurious pulses at the rate of the control signal, and detecting the high frequency spurious pulses and reconstituting the control signal. According to one embodiment, the switch means is driven by a control signal bearing data, such that data- bearing high frequency spurious pulses are emitted at the rate of the control signal. According to one embodiment, the control signal is a coded signal. According to one embodiment, the electricity distribution network carries an alternating voltage and the control signal is synchronized with the waveform of the alternating voltage, so that the switch is only closed when the alternating voltage is in the vicinity of its peak value. According to one embodiment, the alternating voltage is considered to be in the vicinity of its peak value when it has an amplitude at least equal to 50% of its peak value. According to one embodiment, the control signal is synchronized with the waveform of the alternating voltage so that the switch is only open when the alternating voltage is in the vicinity of zero. According to one embodiment, the control signal consists of pulses of constant duration for closing/opening the. switch means, each closing/opening pulse comprising a rising edge and/or a high level causing a change in the open or closed state of the switch and a falling edge and/or a low level causing a reverse change in the state of the switch. According to one embodiment, the control signal comprises closing/opening pulses of a duration less than 1/8th of the period of the alternating voltage. According to one embodiment, the electric element is a capacitor, a resistance, a light-emitting diode or a combination of at least two of these elements. According to one embodiment, spurious pulses are neutralized, rejected or ignored, and are not taken into account to reconstitute the control signal. According to one embodiment, the detection of the spurious pulses comprises the production of a signal mirroring the voltage carried by the electricity distribution network, the high-pass filtering of the mirroring signal, the sampling of the mirroring signal according to a determined sampling window, for obtaining digital samples of the mirroring signal, and the analysis of the samples of the mirroring signal. The present invention also relates to a method for remotely measuring the local electricity consumption of an electric appliance connected to an electricity distribution network carrying a determined voltage, comprising a step of measuring the electricity consumption of the device by means of an on-board current sensor, a step of sending and a step of receiving a piece of information relating to the electricity consumption measured implemented in accordance with the method according to the present invention. The present invention also relates to a method for identifying an electric appliance connected to an electricity distribution network carrying a determined voltage, comprising a step of emitting a series of high frequency spurious pulses forming a code for identifying the device, implemented in accordance with the method according to the present invention. According to one embodiment, the electric appliance is a circuit-breaker, and the emission of the identification code is only triggered when the circuit- breaker has tripped. The present invention also relates to a device for sending and receiving a piece of information via an electricity distribution network carrying a voltage, comprising: - a pulse-emitting device for emitting pulses on the network comprising an electric element and a switch means for linking the electric element to the electricity distribution network, the electric element naturally emitting high frequency spurious pulses when it is connected to the network by the closing of the switch means and/or when it is disconnected from the network by the opening of the switch means, and means for applying to the switch means a control signal of determined shape so that the electric element emits a series of high frequency spurious pulses at the rate of the control signal, and - a device for receiving the high frequency spurious pulses comprising means for reconstituting the control signal. According to one embodiment, the device comprises means for supplying to the switch means a data-bearing control signal. According to one embodiment, the device comprises means for supplying to the switch means a coded control signal. According to one embodiment provided for an electricity distribution network carrying an alternating voltage, the receiving device comprises means for monitoring the amplitude of the alternating voltage, supplying a signal for authorizing pulse emitting having a determined value when the alternating voltage is in the vicinity of its peak value, and means for only closing the switch when the signal for authorizing pulse emitting has the determined value. According to one embodiment, the monitoring means supply a signal for authorizing pulse emitting having the determined value when the amplitude of the alternating voltage is at least equal to 50% of its peak value. According to one embodiment, the monitoring means comprise a rectifier supplying a single- or full-wave rectified voltage the amplitude of which is representative of the amplitude of the alternating voltage, and a comparator receiving a reference voltage at one input and the rectified voltage at another input, supplying the signal for authorizing data sending. According to one embodiment, the means for supplying the control signal supply a control signal consisting of pulses of constant duration for closing/opening the switch means, each pulse comprising a rising edge and/or a high level causing a change in the open or closed state of the switch and a falling edge and/or a low level causing a reverse change in the state of the switch. According to one embodiment, the means for supplying the control signal supply closing/opening pulses of a duration at least less than l/8th of the period of the alternating voltage. According to one embodiment, the electric element is a capacitor, a resistance, a light-emitting diode or a combination of at least two of these elements. According to one embodiment, the switch means is a triac, a MOS transistor or a relay. According to one embodiment, the control signal is supplied by a microcontroller or a microprocessor. According to one embodiment, the pulse-emitting device comprises means for measuring current and is arranged for sending a piece of information, in the form of high frequency spurious pulses, relating to a current measured. According to one embodiment, the receiving device comprises means for filtering, rejecting or ignoring spurious pulses so as not to take these pulses into account when reconstituting the control signal. According to one embodiment provided for an electricity distribution network carrying an alternating voltage, the receiving device comprises means for supplying a signal mirroring the alternating voltage, and means for high-pass filtering the mirroring signal, to extract the high frequency spurious pulses therefrom. According to one embodiment, the receiving device comprises an antenna for detecting the high frequency spurious pulses by using an electromagnetic component of the spurious pulses. According to one embodiment, the receiving device comprises means for sampling the signal received, and means for analyzing the samples of the signal received, to detect the presence of high frequency spurious pulses. The present invention also relates to a circuit- breaking device having a closed state and an open state, and a pulse-emitting device according to the present invention, for emitting a determined series of pulses when the circuit-breaking device is in the open state. According to one embodiment, the device comprises a switch with pilot light that switches from the open state to the closed state when the circuit-breaking device switches from the closed state to the open state, and all or . part of the pulse-emitting device is electrically powered through the switch with pilot light, such that the pulse-emitting device is inactive while the circuit-breaker is in the closed state. These and other objects, features and advantages of the present invention will be explained in greater detail in the following description of the method according to the present invention and of various examples of application described in the form of devices implementing the method, given in relation with, but not limited to the accompanying drawings, in which: - Figure 1 represents the appearance of a high frequency spurious pulse, - Figure 2 schematically represents a device implementing the method according to the present invention, - Figures 3A, 3B are timing diagrams showing, in a general manner, the method according to the present invention, Figure 3C represents the waveform of a voltage distributed by an electricity distribution network, - Figures 3D, 3E are timing diagrams of signals showing a first embodiment of the method according to the present invention, - Figure 4A represents, with an expanded time scale, the waveform of a voltage distributed by an electricity distribution network, - Figures 4B, 4C are timing diagrams of signals showing a second embodiment of the method according to the present invention, Figure 5 is the wiring diagram of an example of embodiment of a pulse-emitting device according to the present invention, - Figure 6 represents in block form another example of embodiment of a pulse-emitting device according to the present invention, and - Figure 7 represents in block form a circuit-breaker according to the present invention. Figure 1 represents the appearance of a spurious pulse I emitted naturally by an electric element when it is switched on. Such a spurious pulse is independent of the electricity consumption of the electric element and takes the shape of a high frequency alternating wave train, typically of a frequency in the order of 20 MHz. The duration of this spurious pulse is of several hundreds of nanoseconds, typically 250 nanoseconds. Its amplitude U can range from about ten millivolts to several Volts (under a voltage of 220 Volts) according to the reactive component of the element and the power it absorbs. Upon receipt, due to the limitations of the bandwidth of the measuring channels (measurement equipment and distribution network), the pulses collected are broader and in the order of about ten microseconds, i.e. a broadening by a factor 40 of the initial pulse. As indicated above, the present invention proposes controlling by an electric element, the emission of high frequency spurious pulses, to obtain a series of pulses having a sought profile, instead of artificially reproducing such pulses. Figure 2 shows the method according to the present invention. An electric element 1 is linked through a switch 2 to an electricity distribution network 3 carrying an alternating voltage Uac. The network 3 is here single phase and the electric element 1 is linked to the phase wire (PH) and to the neutral wire (NL) of the network, the switch 2 being interposed between the phase wire and the corresponding terminal of the electric element. The switch 2 comprises a control terminal to which a control signal CS is applied that controls the closing and the opening of the switch. The switch 2 is of any appropriate type, for example a monostable switch of normally open type (MOS or bipolar transistor, monostable relay...) or a bistable switch (triac, bistable relay...). The element 1 can be any type of electric element producing spurious pulses of desired form (duration, amplitude...), such as an electric bulb, a light-emitting diode (LED), a capacitor, a high value resistance or a combination of these elements for example. The electric element preferably has a high impedance to avoid the appearance of a high switching current on the network. The electric element is for example a 250V capacitor of low value (C) having a high impedance Z (Z=l/2ηFC) at the frequency (F) of the voltage Uac, generally 50 or 60 Hz. The control signal CS is a signal with two states "1" and "0", the "1" corresponding to a determined control voltage and the "0" corresponding to another determined control voltage, that can be the ground potential. Conventionally, it is considered that the switch is closed (on) when the signal CS is on 1 (monostable switch) or when the signal CS changes from 0 to 1 (bistable switch) and that the switch is open (off) when the signal CS is on 0 or changes from 1 to 0. As will be seen below, the signal CS is capable of being applied directly to the control terminal of the switch or through a driver stage. Thus, within the meaning of the present invention, the signal CS represents the logic control signal of the switch. It can constitute the primary control signal of the switch, i.e. the signal that is effectively applied to the control terminal of the switch, if it is compatible with the electrical characteristics of this control terminal. In summary, the method according to the present invention is based on the emission of high frequency pulses designated here and in the claims as being "spurious" pulses, to distinguish them from pulses produced artificially. However, the term "spurious" does not mean that the method according to the present invention produces interference and is therefore incompatible with the legislation aiming to regulate pollution on electric networks. On the contrary, due to the very short duration of the spurious pulses, the method according to the present invention is less "intrusive" and less interfering than classical methods based on the injection of a carrier signal into the electric network or the injection of capacitor discharge pulses. Figures 3A, 3B, 3C show the method according to the present invention in greater detail. Figure 3A represents an example of any shape of signal CS and Figure 3B represents the amplitude, in Volts, of the high frequency spurious pulses produced on the network 3. Figure 3C represents the waveform of the voltage Uac at the moment at which the spurious pulses are emitted. Upon each change from the state 0 to the state 1 of the signal CS, the switch 2 becomes on, the electric element 1 receives the voltage Uac and a closing spurious pulse I1, I3, I5 (or connection pulse) is emitted. Upon each change from the state 1 to the state 0 of the signal CS, the switch 2 changes into the open state (OFF) , the element 1 is disconnected from the network and an opening spurious pulse 12, 14, 16 (or disconnection pulse) is emitted. By jointly observing Figures 3B and 3C, it can be seen that the amplitude of the spurious pulses is not constant and depends, in particular, on the moments at which these pulses are emitted. More particularly, the following experimental observations have been made: - Observation No. 1: the amplitude of the closing or opening spurious pulses depends on the amplitude of the voltage Uac at the moment at which the closing or the opening of the switch occurs, Observation No. 2: in similar emission conditions, certain spurious pulses, here the (disconnection) opening spurious pulses, can have an amplitude below that of the closing spurious pulses and not exceeding 10% of the amplitude of the closing spurious pulses. Thus, in accordance with Observation No. 1, it can be seen in Figure 3B that the closing spurious pulse I1 is maximal since it is emitted at an instant t1 at which the voltage Uac is equal to its peak value Umax (a spurious pulse of same amplitude would be obtained with the peak value -Umax). Furthermore, the closing spurious pulses I3, I5 are emitted at instants t3, t5 at which the voltage Uac has a low amplitude, and have an amplitude much lower than that of the pulse I1. Similarly, the opening spurious pulse 14 is emitted at an instant t4 at which the voltage Uac is below its peak value Umax or -Umax, and has an amplitude below that of the opening spurious pulse I2. In accordance with Observation No. 2, it can be seen that the opening spurious pulse I2, although emitted at an instant t2 at which the voltage Uac is maximal (i.e. in the same conditions) , has an amplitude clearly below that of the spurious pulse I1. Finally, the opening spurious pulse I6 is emitted at an instant t6 at which the voltage Uac is maximal (-Umax) and has an amplitude higher than those of the closing spurious pulses I3, I5 that are emitted in unfavorable conditions, despite the fact that they would have a higher amplitude if they were emitted in the same conditions. In one embodiment of the present invention based on these observations, the following rules are applied: 1) The opening spurious pulses are not considered here to be "exploitable", as they have an amplitude that is too low relative to the closing spurious pulses. Thus, these pulses are neutralized upon emission, or rejected upon receipt in a manner described below. 2) The closing spurious pulses are emitted when the voltage Uac is close to the maximum value, i.e. when the voltage Uac has an amplitude higher than or equal to x% of the value Umax, x being a parameter to be defined experimentally and preferably at least equal to 50. Figures 3D, 3E show a first embodiment of the method wherein the opening spurious pulses are neutralized upon emission. Figure 3D represents the shape of the signal CS and Figure 3E represents the amplitude of the pulses obtained. The signal CS is synchronized with the waveform of the voltage Uac, represented in Figure 3C. More particularly, the signal CS changes to 1 when the voltage Uac is equal to Umax or -Umax and changes to 0 when the voltage Uac is zero. In other terms, the switch 2 changes from the closed state to the open state when the voltage Uac is zero and the opening spurious pulses are never emitted, as can be seen in Figure 3E. However, the amplitude of the closing spurious pulses is maximal since the switch is only closed at the instants at which the voltage Uac is maximal. It will be understood that the profile of signal CS represented in Figure 3D only constitutes a template determining the authorized instants of closing and opening of the switch 2. Thus, various series of pulses each having their own profile can be emitted, and each profile can be allocated to the identification of a determined electric appliance, as was considered by EP 1,136,829 but by using synthesis pulses. According to one aspect of the present invention, this template is used to transmit data. For example, as shown in Figure 2, data DTx to be sent, possibly in coded form, are applied to a circuit 4 that supplies the control signal CS while monitoring the voltage Uac. The data can be sent bit by bit or as a frame comprising for example one start bit and 8 data bits, and possibly a signature field, for example a parity bit. In the absence of coding, a closing of the switch 2 (i.e. the emission of a spurious pulse) corresponds to sending a bit on 1, while the absence of closing of the switch at the moment imposed by the template, i.e. an absence of any spurious pulse, corresponds to sending a bit on 0. In a network 50Hz, the period T of the voltage Uac is of 20 ms, such that 100 spurious pulses (i.e. 100 non-coded bits) can be sent in one second. Although this pulse rate is slow, it is sufficient for certain identification or data transmission applications, particularly an application to the management of a stock of streetlights described below. A second embodiment of the method is provided for sending data or trains of pulses with a higher rate. This embodiment is shown by Figures 4A, 4B, 4C. Here, the closing spurious pulses are not neutralized upon emission and are ignored upon receipt, thanks to an adequate setting of a detection threshold. To determine the instants for authorizing the emission of the spurious pulses, a threshold U1 close to the peak value Umax is chosen, for example a threshold equal to 0.66 Umax. As represented in Figure 4A, this threshold enables two time windows for authorizing emission TW1, TW2 to be defined, at each half- period T/2 of the voltage Uac. The window TW1 encompasses the values of the voltage Uac that are positive and higher than U1 and the window TW2 encompasses the values of the voltage Uac that are negative and lower than -U1 (i.e. higher than U1 in absolute value). Figure 4B represents the template of the control signal CS. The latter comprises trains of closing/opening pulses that are applied to the switch 2 inside each time window TW1, TW2. As can be seen in Figure 4C, each closing/opening pulse causes the emission on the network of two high frequency spurious pulses, i.e. a closing spurious pulse upon the rising edge of the closing/opening pulse and an opening spurious pulse upon the falling edge of the closing/opening pulse. As indicated above, the opening spurious pulses are of an amplitude much lower than that of the closing spurious pulses and are destined to be filtered upon receipt. With a voltage Uac of frequency 50 Hz, the duration of the windows TW1, TW2 is in the order of 6 to 7 ms and the number of closing/opening pulses that can be sent is high. Thus, if each closing/opening pulse causes the emission of two high frequency spurious pulses of a duration in the order of 10 microseconds each (pulse width upon receipt, useful signal), the minimum duration of each closing/opening pulse must be at least equal to twice the duration of the spurious pulses, i.e. in the order of 10 to 20 microseconds. In these conditions, by choosing this minimum pulse duration as a template, and without taking into account any limitations of the switch in terms of switching frequency, each time window can contain approximately 300 closing/opening pulses and thus offers a high data rate relative to the first embodiment of the method of the present invention, in the order of 30,000 pulses per second. As above, the data can be sent in raw form, one bit then corresponding to one pulse, or coded by any appropriate coding protocol, one bit then corresponding to several pulses. The data, whether coded or not, can be sent in the form of individual bits or as a frame comprising a start of frame field, a data field, and possibly an end of frame field that can comprise a verification field of CRC or parity type. It will be understood by those skilled in the art that various alternative embodiments and applications of this method are possible. For example, the emission of the high frequency spurious pulses can be provided only once per period instead of twice per period, for example when the voltage Uac is equal to +Umax (first embodiment) or is higher than +U1 (second embodiment). Figure 2 also schematically represents two examples of embodiment of pulse detectors 10, 15 according to the present invention. The detector 10 is an inductive reception device the operating principle of which has already been described in EP 1,136,829. It comprises an input transformer for extracting from the voltage Uac a mirroring signal that is analyzed to detect the high frequency spurious pulses. The transformer can be simply formed by a coil 11 arranged around the phase wire (PH) of the network, at a source point of the distribution of the current, for example near an electricity meter. The coil supplies the mirroring signal that is applied to a high-pass filter 12 to remove its low frequency alternating component. The output of the filter is applied to a sample hold analog-to-digital converter 13 ("sample hold AD converter") that supplies digital samples of the filtered voltage Uac, in synchronization with a sampling period defining an observation window. The choice of the sampling period and of the duration of the observation window depends on the period of emission of the high frequency spurious pulses, i.e. the period between two closing/opening pulses. If the spurious pulses are emitted with a high frequency, in accordance with the second embodiment of the method of the present invention, the observation window is chosen to be sufficiently short to obtain a fineness of analysis enabling the pulses to be differentiated within the pulse trains emitted. The analysis of the samples of the voltage Uac is performed by an analysis circuit 14, generally a specific logic circuit, which analyzes the amplitude of the samples received and detects the pulses of an amplitude above the threshold for rejecting the closing spurious pulses, so as to keep only the opening spurious pulses. The circuit 14 thus reconstitutes the control signal CS, and also deduces therefrom the data DTx when the signal CS is data bearing. If they are received in coded form, the data DTx can also be decoded by the circuit 14. The detector 15 is a contactless device comprising an antenna 16, an antenna booster 17 and a high-pass filter 18 for removing the signals of frequency below that of the pulses to be detected. In addition to these elements, as above, a sample hold AD converter 13 and an analysis circuit 14 are provided. This embodiment of a pulse detector according to the present invention is based on the fact that the high frequency spurious pulses are found both as electric pulses on the network and as electromagnetic pulses that can be detected in the same way as any radio frequency signal. The detector 15 is preferably arranged near the pulse-emitting equipment, such as in the premises in which the equipment is installed for example. Figure 5 represents one simple and inexpensive embodiment of a pulse-emitting device 20 according to the present invention, intended to be installed in appliances or electric equipment. The device 20 comprises two terminals T1, T2 for connection to the electricity distribution network 3, a switch circuit 30, an electric supply circuit 40, a circuit 50 for monitoring the alternating voltage Uac and a control circuit 60. The terminal Tl is connected to the phase wire (PH) and the terminal T2 connected to the neutral wire (NL) of the network 3. In accordance with the method of the present invention, the switch circuit 30 comprises an electric element 31, here a capacitor, and a switch 32. The switch 32 is for example a triac or a MOS transistor (a triac being represented in Figure 5). The switch 32 has one terminal connected to the terminal Tl, another terminal connected to one terminal of the capacitor 31, and a control terminal (trigger of the triac or gate of the MOS transistor) driven by the control circuit 60. The other terminal of the capacitor 31 is connected to the terminal T2. The supply circuit 40 comprises a diode bridge rectifier 41 having two input terminals connected to the terminals I1, I2 through resistances 42, 43, a terminal linked to the ground and an output terminal supplying a full-wave rectified voltage Ur. The voltage Ur is applied to one input of an adjusting assembly 46 that is linked to the ground through an overvoltage clipper diode 44 and a smoothing capacitor 45. The output of the adjusting assembly 46 is linked to a stabilization capacitor 47 and supplies a voltage Vcc for supplying the circuits 50, 60. The monitoring circuit 50 comprises a diode rectifier bridge 51 having two input terminals connected to the terminals I1, I2 through resistances 52, 53, respectively, a terminal linked to the ground and an output terminal supplying a full-wave rectified voltage Ur'. The rectified voltage Ur1 is applied to the positive input of a differential amplifier 56 that is linked to the ground through an overvoltage clipper diode 54 and a load resistor 55. The negative input of the amplifier 56 receives a reference voltage Vref supplied by the mid-point of a potentiometer 57 the anode of which receives the voltage Vcc and the cathode of which is grounded. The differential amplifier 56, here operating as a comparator, supplies a signal ENB ("Enable") that is on 1 (Vcc) when the full-wave rectified voltage Ur1 is higher than the reference voltage Vref, and is on 0 (ground) in the opposite case. The potentiometer 57 enables the voltage Vref to be adjusted so as to define the width of the emission-authorizing time windows TW1, TW2. By increasing the voltage Vref, the width of the windows decreases and two authorization instants are finally obtained corresponding to Uac=Umax and Uac=-Umax, corresponding to the implementation of the first embodiment of the method according to the present invention (i.e. one pulse per half-period of the voltage Uac) . It will be noted that the monitoring circuit 50 may comprise only a single-wave rectifier if pulses are only to be emitted on one of the two half-periods of the voltage Uac. The circuit 60 supplies the control signal CS applied to the control terminal of the switch 32. The circuit 60 comprises an inexpensive microcontroller 61, incorporating on the same silicon microchip a microprocessor and its input/output ports P0, P1, P2, P3. . ., a program memory, data memories, a quartz oscillator... The port P0 receives the signal ENB, the port P1 supplies the control signal CS, and the ports P2 P3 are, optionally, used as ports for communicating with the microcontroller for test, maintenance, programming or other operations and are linked to auxiliary terminals ATI, AT2 of the device 20. The microcontroller detects the change to 1 of the signal ENB by polling the port P0 or by interruption declared on this port. The port P1 drives the switch 32 through a driver stage comprising a control block 62 and a transistor 63. The control block 62 has an output connected to the control terminal of the switch 32 and an input connected to the collector of the transistor 63, the emitter of which is connected to the ground and the base of which receives the control signal CS. Once on-board an appliance, the device 20 can be used to transmit data or, more simply, to emit a series of non data-bearing pulses, having an invariable predetermined profile, used for example to identify the electric appliance. In this last case, the circuit 60 can be a logic circuit with a basic architecture, comprising a synchronization input receiving the signal ENB and supplying the control signal CS. By providing a microcontroller or microprocessor, it is possible to implement more complex applications requiring processing and transmitting data, as will be seen in the examples of applications described below. Thus, various applications of the device 20 are possible. One example of an application is the control of streetlights in a built-up area. To that end, each streetlight is equipped with such a device and cyclically sends a piece of information about its on or off state. This piece of information can be sent at low rate in accordance with the first embodiment of the method of the present invention, since it is in no way urgent and can be processed over periods of time of several minutes. With a reasonable investment, hundreds of streetlights can be equipped with devices according to the present invention. By giving each streetlight one second every minute to emit pulses representative of the state of the streetlight, 60 streetlights can send information in one minute. A reception unit arranged at a source point of the urban electricity distribution network or at a bypass node, is sufficient to receive the information sent by a plurality of streetlights. Various alternative embodiments of the pulse-emitting device according to the present invention can, furthermore, be made according to the intended applications. Figure 6 represents a device 20' that comprises, in addition to the circuits 30, 40, 50 and 60 that have just been described, a current sensor 70 linked to a measuring circuit 71. The measuring circuit 71 sends the control circuit 60 data relating to current measurements taken by means of the sensor 70. The microcontroller of the device 60 analyzes the results of the measurements and decides whether or not to send them according to what is provided in the application program loaded into its program memory. This program can for example provide for the microcontroller to send a piece of information on the network relating to the current measured solely when the latter changes from 0 to a non-zero value, then changes from one consumption bracket to another, for example from the bracket ranging from 0 to 1 A to the bracket ranging from 1 to 2 A, from the bracket ranging from 1 to 2 A to the bracket ranging from 2 to 3 A, etc. This piece of information can take the shape of an eight-bit word (byte) having a first value when the current measured changes from 0 to a non-zero value, then a second value when the current changes from the bracket 0-1 A to the bracket 1-2 A, etc. The device 20' can be arranged in an electric plug, particularly a piggyback plug used to electrically supply one or more appliances, or be installed on-board an electric appliance, so as to measure the current passing through the electric plug or the current consumed by the appliance in which it is installed. Such an application enables the method of measuring the electricity consumption of electric appliances described by EP 1,136,829 to be perfected. Indeed, when the current changes from 0 to a non-zero value, the emission of the first byte enables the appliance or the group of appliances that is switched on to be identified on the network. Then, the emission of bytes in relation with the change in consumption bracket enables the consumption and locating measurements taken on the network in the manner proposed by EP 1,136,829 to be confirmed. Another example of application of the method and device according to the present invention will now be described. Many industrial installations comprise circuit- breakers grouped together in electric cabinets, the closed (switched on) or open (tripped) state of which must be monitored. To that end, in the current state of the technique, circuit-breakers have been developed that are equipped with a switch with pilot light which, through a mechanical actuator, switches from the open state to the closed state when the circuit-breakers trip. Thus, in such installations, the many circuit-breakers arranged in electric cabinets each have a switch with pilot light linked by two wires to a centralizer, which monitors the state of the circuit-breakers to detect power failures. The present invention proposes removing the quantities of electric wires linking the switches with pilot light to the centralizer, by installing on-board a circuit-breaker a device according to the present invention that is arranged to monitor the state of the circuit- breaker and to send a piece of information when the circuit-breaker is in the open state. This piece of information can for example consist in a code for identifying the circuit-breaker, the simple emission of which means that the circuit-breaker has tripped. Figure 7 represents an example of embodiment of a circuit-breaker 90 according to the present invention, comprising a combination of a classical circuit-breaker 80 and a device 20 according to the present invention. The structure of the device 20 is identical to the one described in relation with Figure 5 and will not be described again. The circuit-breaker 80 comprises input terminals T3, T4 connected to the phase and neutral wires of the upstream part of the electricity distribution network, and output terminals T5, T6 connected to the phase and neutral wires of the downstream part of the electricity distribution network. The circuit-breaker 80 also comprises control terminals T7, T8 linked to the terminals of a switch with pilot light 81. The terminals T1 and T2 of the device 20 are connected to the terminals T3 and T4 of the circuit-breaker 80 such that the device 20 is electrically powered when the circuit-breaker is in the open state. The detection by the device 20 of the state of the circuit-breaker 80, is here performed by means of the switch with pilot light. Such a detection can be performed in various ways. For example, the microcontroller of the control circuit 60 can comprise two input/output ports connected to the terminals T7, T8 to cyclically monitor the on or off state of the switch with pilot light. However, this solution has the disadvantage that the device 20 must permanently be switched on, and implies consuming electricity. One advantageous solution, represented in Figure 7, is that the supply voltage Vcc supplied by the circuit 40 is applied to the monitoring circuit 50 and to the control circuit 60 through the switch with pilot light 81. Thus, the device 20 stays switched off while the circuit-breaker is in the triggered state. When the switch with pilot light 81 closes, the circuits 50, 60 are electrically powered and the control circuit 60 implicitly "knows", when it is switched on, that a piece of information must be sent on the electric network. The control circuit 60 is therefore simply programmed for emitting, when it is switched on, a series of pulses enabling the circuit- breaker to be identified. Generally speaking, the integration of the device 20 into a circuit-breaker 80 to obtain the circuit-breaker 90 according to the present invention involves only a minor increase in the cost price of the circuit-breaker, and enables, in return, substantial savings to be made on wiring as a result of removing the electric wires linking the centralizer and the circuit- breakers. A pulse receiver of the type described above enables a wireless centralizer to be produced that is capable of managing hundreds of circuit-breakers and of supplying in real time an indication about the circuit- breakers that are in the tripped state. In the light of the examples described, it will be understood by those skilled in the art that various other alternative embodiments and applications of the present invention are possible. In particular, although various applications of the method of the present invention to an electricity network carrying an alternating voltage have been described, the present invention is also applicable to direct current networks, particularly the 400V DC networks used in industry or on board ships, the 200V DC networks, including the low voltage 12V DC networks present in motor vehicles. In particular, the method according to the present invention can be used to cause a vehicle device (such as a car headlamp for example) to send a piece of information about its state (on, off, out of order, etc.) . In the applications to direct current networks, the monitoring of the waveform of the voltage carried by the network is no longer necessary since as this voltage is direct, it always has an optimal value for the emission of the high frequency spurious pulses. As the present invention is based on a phenomenon little studied until now, it lies with those skilled in the art to complete the teaching that has just been described by experimental observations. Thus, further experiments have revealed that the amplitude of the connection spurious pulses can prove to be equal or even greater than that of the disconnection spurious pulses. This can particularly be observed by using as electric element a low- value resistor, for example of a few ohms, which is cyclically connected to the network with a very short connection time, for example a few microseconds, and which is thus passed through by a high current, for example several amperes, that does not interfere with the network due to its short duration. It can then be seen that the amplitude of the spurious pulses emitted when the resistor is disconnected from the network is substantially greater than that of the spurious pulses emitted when the resistor is connected to the network. In this case, the disconnection pulses can also be used as means of transmitting a piece of information, instead of the connection pulses. Furthermore, both types of connection and disconnection pulses can be detected to obtain a redundant piece of pulse detection information enabling the control signal to be reconstituted with greater reliability. WE CLAIM : 1. A method for transmitting a piece of information through an electricity distribution network (3) carrying a voltage (Uac), comprising the steps of: - connecting, between two wires of the network, an electric element (1, 31) in series with a switch means (2, 32), - applying to the switch means a control signal (CS) of determined shape so that the switch means is closed and opened successively, - detecting the spurious pulses that appear in the network when the switch means is closed or open, each spurious pulse comprising a high frequency wave train, and - reconstituting the control signal (CS). 2. Method as claimed in claim 1, wherein the switch means (2, 32) is driven by a control signal (CS) bearing data (DTx), such that data-bearing high frequency spurious pulses are emitted at the rate of the control signal. 3. Method as claimed in claim 2, wherein the control signal (CS) is a coded signal. 4. Method as claimed in one of claims 1 to 3, wherein the electricity distribution network (3) carries an alternating voltage (Uac) and wherein the control signal (CS) is synchronized with the waveform of the alternating voltage (Uac), so that the switch (2, 32) is only closed when the alternating voltage is in the vicinity of its peak value (Umax, -Umax). 5. Method as claimed in claim 4, wherein the alternating voltage (Uac) is considered to be in the vicinity of its peak value when it has an amplitude (U1, U2) at least equal to 50% of its peak value. 6. Method as claimed in one of claims 4 and 5, wherein the control signal (CS) is synchronized with the waveform of the alternating voltage so that the switch is only open when the alternating voltage is in the vicinity of zero. 7. Method as claimed in one of claims 1 to 6, wherein the control signal (CS) consists of pulses of constant duration for closing/opening the switch means, each closing/opening pulse comprising a rising edge and/or a high level causing a change in the open or closed state of the switch and a falling edge and/or a low level causing a reverse change in the state of the switch. 8. Method as claimed in claim 7, wherein the control signal comprises closing/opening pulses of a duration less than l/8th of the period of the alternating voltage. 9. Method as claimed in one of claims 1 to 8, wherein the electric element is a capacitor, a resistance, a light- emitting diode or a combination of at least two of these elements. 10. Method as claimed in one of claims 1 to 9, wherein spurious pulses are neutralized, rejected or ignored, and are not taken into account to reconstitute the control signal. 11. Method as claimed in claim 10, wherein the detection of the spurious pulses comprises the production of a signal mirroring the voltage carried by the electricity distribution network, the high-pass filtering of the mirroring signal, the sampling of the mirroring signal according to a determined sampling window, for obtaining digital samples of the mirroring signal, and the analysis of the samples of the mirroring signal. 12. A method for remotely measuring the local electricity consumption of an electric appliance connected to an electricity distribution network carrying a determined voltage, comprising the steps of: - measuring the electricity consumption of the appliance by means of an on-board current sensor, and transmitting a piece of information through the electricity distribution network in accordance with the method as claimed in one of claims 2 to 11. 13. A method for identifying an electric appliance connected to an electricity distribution network (3) carrying a determined voltage (Uac), comprising a step of transmitting a piece of information through the electricity distribution network in accordance with the method as claimed in one of claims 1 to 11, wherein the piece of information is transmitted as a series of high frequency spurious pulses forming a code for identifying the device. 14. Method as claimed in claim 13, wherein the electric appliance is a circuit-breaker, and wherein the transmission of the identification code is only triggered when the circuit-breaker has tripped. 15. A device for sending and receiving a piece of information via an electricity distribution network (3) carrying a voltage (Uac), comprising: - a pulse-emitting device (20, 20') for emitting pulses on the network (3) comprising: - an electric element (31) and a switch means in series, connected between two wires (PH, NL) of the network, and - means (60, 61) for applying to the switch means a control signal (CS) of determined shape so that the switch means is closed and opened successively, and - a device (10, 15) for detecting spurious pulses that appear in the network once the switch means is closed or opened, each spurious pulse comprising a high frequency wave train, the detecting device comprising means (12, 13, 14, 16, 17) for reconstituting the control signal (CS). 16. Device as claimed in claim 15, comprising means (61) for supplying the switch means with a data-bearing control signal (CS). 17. Device as claimed in claim 16, comprising means (61) for supplying to the switch means a coded control signal (CS). 18. Device as claimed in one of claims 15 to 17, provided for an electricity distribution network carrying an alternating voltage (Uac), wherein the pulse-emitting device comprises means (50) for monitoring the amplitude of the alternating voltage (Uac), supplying a signal (ENB) for authorizing pulse emitting having a determined value when the alternating voltage is in the vicinity of its peak value (Umax, -Umax), and means for only closing the switch when the signal for authorizing pulse emitting has the determined value. 19. Device as claimed in claim 18, wherein the monitoring means (50) supply a signal for authorizing pulse emitting having the determined value when the amplitude of the alternating voltage is at least equal to 50% of its peak value. 20. Device as claimed in one of claims 18 and 19, wherein the monitoring means (50) comprise a rectifier (51) supplying a single- or full-wave rectified voltage (Ur') the amplitude of which is representative of the amplitude of the alternating voltage (Uac), and a comparator (56) receiving a reference voltage (Vref) at one input and the rectified voltage (Ur') at another input, supplying the signal (ENB) for authorizing data sending. 21. Device as claimed in one of claims 15 to 20, wherein the means (60, 61) for supplying the control signal supply a control signal (CS) consisting of pulses of constant duration for closing/opening the switch means, each pulse comprising a rising edge and/or a high level causing a change in the open or closed state of the switch and a falling edge and/or a low level causing a reverse change in the state of the switch. 22. Device as claimed in claim 21 and one of claims 18 to 20, wherein the means (60, 61) for supplying the control signal supply closing/opening pulses of a duration at least less than l/8th of the period of the alternating voltage. 23. Device as claimed in one of claims 15 to 22, wherein the electric element is a capacitor (31), a resistance, a light-emitting diode or a combination of at least two of these elements. 24. Device as claimed in one of claims 15 to 23, wherein the switch means is a triac (32), a MOS transistor or a relay. 25. Device as claimed in one of claims 15 to 24, wherein the control signal (CS) is supplied by a microcontroller or a microprocessor (61). 26. Device as claimed in one of claims 15 to 25, wherein the pulse-emitting device (20') comprises means (70, 71) for measuring current and is arranged for sending a piece of information, in the form of high frequency spurious pulses, relating to a current measured. 27. Device as claimed in one of claims 15 to 26, wherein the detecting device (10) comprises means (13, 14) for filtering, rejecting or ignoring spurious pulses so as not to take these pulses into account when reconstituting the control signal. 28. Device as claimed in one of claims 15 to 27, provided for an electricity distribution network carrying an alternating voltage (Uac), wherein the detecting device (10) comprises means for supplying a signal mirroring the alternating voltage, and means (12) for high-pass filtering the mirroring signal, to extract the high frequency spurious pulses therefrom. 29. Device as claimed in one of claims 15 to 27, wherein the detecting device (15) comprises an antenna (16) for detecting the high frequency spurious pulses by using an electromagnetic component of the spurious pulses. 30. Device as claimed in one of claims 28 and 29, wherein the detecting device (10, 15) comprises means (13) for sampling the signal received, and means (14) for analyzing the samples of the signal received, to detect the presence of high frequency spurious pulses. 31. A circuit-breaking device (90) having a closed state and an open state, characterized in that it comprises a pulse-emitting device (20) as claimed in one of claims 15 to 25, for emitting a determined series of pulses when the circuit-breaking device is in the open state. • 32. Circuit-breaking device as claimed in claim 31, comprising a switch with pilot light (81) that switches from the open state to the closed state when the circuit- breaking device switches from the closed state to the open state, and wherein all or part (50, 60) of the pulse- emitting device (20) is electrically powered through the switch with pilot light (81), such that the pulse-emitting device is inactive while the circuit-breaker is in the closed state. ABSTRACT Method And Device For Transmitting Information Through A Power Distribution Network A method for transmitting a piece of information through an electricity distribution network (3) carrying a voltage (Uac), comprising the steps of: connecting, between two wires of the network, an electric element (1, 31) in series with a switch means (2, 32), applying to the switch means a control signal (CS) of determined shape so that the switch means is closed and opened successively, detecting the spurious pulses that appear in the network when the switch means is closed or open, each spurious pulse comprising a high frequency wave train, and reconstituting the control signal (CS).

Full Text

The present invention relates to a method and a device for
transmitting a piece of information through, an electricity
distribution network.
The electric line has been used for many years as a
low-rate data transmission means, particularly in home
automation applications, to remotely control electric
appliances (such as electric shutters for example). The
known data transmission methods involve injecting, into the
network, a carrier signal which is modulated appropriately
to carry, data. The disadvantage of these methods is that
they require the injection of such a carrier signal. They
are therefore intrusive and cause interference, and are
complex to implement.
The present invention aims to provide a method for
transmitting a piece of information via an electricity distribution
network which is less intrusive and causes less interference than
the known methods. The intended applications are mainly the
transmission of binary data but also the transmission of a non-
binary piece of information, for example a series of pulses having a
predetermined profile enabling an electric appliance to be
identified without requiring the information to be rebuilt in binary
form.
As set forth in the patent EP 1 136 829, any electric
appliance or element, particularly motors, pumps, transformers,
electric bulbs, electric or electronic circuits, generates, when
switched on and switched off, a high frequency spurious signal
having an electromagnetic origin. As this signal is very short in
duration, it forms a high frequency spurious pulse naturally emitted
by the electric element. Such a spurious pulse forms a sort of
unique signature that is representative of the electric appliance
and of its location on the electricity distribution network. Thus,
the patent EP 1 136 829 suggests detecting and analyzing the high

frequency pulses emitted an the network by electric appliances, so
as to identify the appliances that are switched on or switched off.
The aforementioned patent also suggests providing a pulse
synthesizer capable of supplying a pulse that replaces the spurious
pulse naturally emitted when the amplitude of the latter is too low
to be validly detected. The use of a pulse synthesizer is also
considered to emit a series of pulses comprising a determined number
of pulses forming a unique signature.
Classically, a pulse synthesizer capable of emitting a series
of pulses comprises for example a HF pulse generator switch, a HF
oscillator, a logic circuit and an output transformer. The HF
oscillator supplies a high frequency signal for switching the HF
switch. The logic circuit supplies a coded signal that is
mixed with the switching signal to obtain a signal for
controlling the switch. The output transformer enables the
series of HF pulses artificially reconstituted to be re-
injected into the electricity distribution network.
However, the cost price and overall dimension of such
a pulse synthesizer are substantial in the context of the
intended applications, which concern mass markets and
demand very low cost prices.
Thus, the present invention provides for transmitting a piece
of information on an electricity distribution network without using
any pulse synthesizer.
More particularly, the present invention provides for
transmitting a piece of information by using the high frequency
spurious pulses naturally emitted by an electric element when the
latter is connected or disconnected from the network. For this
purpose, the electric element is linked to the network by a switch
and the switch is driven by a control signal representative of the
information to be transmitted. Thus, the high frequency spurious

pulses emitted by the electric element mirror the control signal
that itself mirrors the information to be transmitted. The duration
of such pulses, of electromagnetic origin, is very short and is
independent of the time elapsing between the closing and opening of
the switch, which can be much longer.

In prior art, various data transmission methods have already
been proposed based on the emission of pulses in an electricity
distribution network. These are generally voltage or current pulses
generated by the discharge of a capacitor, the duration of the
discharge forming the duration of the pulse. These voltage or
current pulses are directly injected into the network by means of a
switch or are injected by inductive coupling. To be detected, they
require considerable electrical energy to be injected into the
network.
With the present invention, the electrical energy that must be
applied to the network can, on the contrary, be very low or even
almost zero (within the limit of the laws of physics and inductive
phenomena) as it is not an energy-carrier voltage or current pulse
that is detected, but a high frequency spurious pulse that goes with
the connection or the disconnection of the electric element.
In prior art, high frequency spurious pulses are perhaps
unintentionally emitted simultaneously with the emission of voltage
or current pulses, but such spurious pulses emitted unintentionally
are not used as a means for transmitting information and are not
therefore detected as such.
Thus, the document GB 1 153 908 describes a data transmission
method consisting in discharging a capacitor 4 in the electric
network (Cf. page 2 lines 55-121, Figures 1 to 3) and in detecting
the discharge pulses which are superimposed on the alternating
voltage of the network.
The document US 4 090 184 also describes a data transmission
method by discharging a capacitor (Cf. column 17 lines 22-34) and
detecting the discharge pulses.
The document US 5 614 8 11 also describes a data transmission
method by discharging a capacitor (Cf. claim 1, last line).
Moreover, this method interferes with the electric network since the
capacitor is discharged at moments when the alternating voltage
crosses zero (Cf. Fig. 7, column 3 line 61 to column 4 line 16).
The document GB 2__P08 299 also describes a data transmission
method by discharging a capacitor 20 (Cf. claim 1, last line, Figure
1) . Also in this method, the capacitor can be discharged at moments

when the wave of the alternating voltage crosses 0 (Cf. Fig. 18,
"signal pulses at zero crossing") .
The document US 5 486 805 also describes a method comprising
the emission of pulses by discharging a capacitor when the
alternating voltage crosses zero (Cf. Figure 1).
The document US 2003/0156014 describes a method for
transmitting data an an electric network using a plurality of sub-
carrier frequencies (Cf. paragraph Oil) that are injected into the
network by means of a coupling circuit (Cf. 121, Fig. 3).
The document US 2002/0024423 describes a method of injecting
coded data on an electric network by means of a pseudo-noised code
which is modulated by means of a train of electrical energy pulses
without using any sinusoidal carrier. Like the previous ones, this
method is based on injecting energy into the electric network and
not on the use of natural spurious pulses.
The document US 3 714 451 also describes the injection of
energy pulses into an electric network, by discharging a capacitor
(Cf. 25a Figure 2, Figures 4, 5, 7, claim 1).
The document wo 00 /26679 describes a method for detecting the
closing of a switch in which current peaks are injected into a
branch of a network (Cf. Figure 4) controlled by the switch. The
current is injected by a circuit (Cf. Figures 1A or 1B) which
cyclically discharges a capacitor (Cf. 170 or 260) . The current
pulses are short in duration so as to limit the appearance, in
neighboring network branches, of induced current peaks. Therefore,
the induced current peaks are of low amplitude and do not interfere
with the detection of the main current peak. The main current peak
is detected by a detector (Cf. Fig. 2) which comprises a coil (L1)
enabling the current peak to be detected by induction. An amplifier
coupled to the coil electrically supplies an audible alarm (351)
which emits an audible signal when the user approaches the branch in
which the current peaks are injected.
Finally, the document US 4 982 175 describes a telemetry
system that injects pulses on an electric network (Cf. 32, Figure 3)
caused by the discharge of a capacitor (Cf. 26, Figure 2). These
pulses are not high frequency spurious pulses within the meaning of

the present invention and are detected by induction by means of
coils (Cf. 41a to 42b, Figure 6) .
"Thus, the present invention provides a method for transmitting
a piece of information through an electricity distribution network
carrying a voltage, comprising the following steps of: linking an
electric element to the network through a switch means, the electric
element naturally emitting a high frequency spurious pulse when it
is connected to the network by the closing of the switch means
and/or when it is disconnected from the network by the opening of
the switch means, applying to the switch means a control signal of
determined shape so that the electric element emits a predetermined
series of high frequency spurious pulses at the rate of the control
signal, and detecting the high frequency spurious pulses and
reconstituting the control signal.
According to one embodiment, the switch means is
driven by a control signal bearing data, such that data-
bearing high frequency spurious pulses are emitted at the
rate of the control signal.
According to one embodiment, the control signal is a coded
signal.
According to one embodiment, the electricity
distribution network carries an alternating voltage and the
control signal is synchronized with the waveform of the
alternating voltage, so that the switch is only closed when
the alternating voltage is in the vicinity of its peak
value.
According to one embodiment, the alternating voltage
is considered to be in the vicinity of its peak value when
it has an amplitude at least equal to 50% of its peak
value.
According to one embodiment, the control signal is
synchronized with the waveform of the alternating voltage
so that the switch is only open when the alternating
voltage is in the vicinity of zero.
According to one embodiment, the control signal
consists of pulses of constant duration for closing/opening
the. switch means, each closing/opening pulse comprising a

rising edge and/or a high level causing a change in the
open or closed state of the switch and a falling edge
and/or a low level causing a reverse change in the state of
the switch.
According to one embodiment, the control signal
comprises closing/opening pulses of a duration less than
1/8th of the period of the alternating voltage.
According to one embodiment, the electric element is
a capacitor, a resistance, a light-emitting diode or a
combination of at least two of these elements.
According to one embodiment, spurious pulses are neutralized,
rejected or ignored, and are not taken into account to reconstitute
the control signal.
According to one embodiment, the detection of the spurious
pulses comprises the production of a signal mirroring the
voltage carried by the electricity distribution network,
the high-pass filtering of the mirroring signal, the
sampling of the mirroring signal according to a determined
sampling window, for obtaining digital samples of the
mirroring signal, and the analysis of the samples of the
mirroring signal.
The present invention also relates to a method for
remotely measuring the local electricity consumption of an
electric appliance connected to an electricity distribution
network carrying a determined voltage, comprising a step of
measuring the electricity consumption of the device by
means of an on-board current sensor, a step of sending and
a step of receiving a piece of information relating to the
electricity consumption measured implemented in accordance
with the method according to the present invention.
The present invention also relates to a method for
identifying an electric appliance connected to an electricity distribution network carrying a determined
voltage, comprising a step of emitting a series of high
frequency spurious pulses forming a code for identifying
the device, implemented in accordance with the method
according to the present invention.

According to one embodiment, the electric appliance
is a circuit-breaker, and the emission of the
identification code is only triggered when the circuit-
breaker has tripped.
The present invention also relates to a device for sending and
receiving a piece of information via an electricity distribution
network carrying a voltage, comprising:
- a pulse-emitting device for emitting pulses on the network
comprising an electric element and a switch means for
linking the electric element to the electricity
distribution network, the electric element naturally
emitting high frequency spurious pulses when it is
connected to the network by the closing of the switch means
and/or when it is disconnected from the network by the opening of
the switch means, and means for applying to the switch means a
control signal of determined shape so that the electric element
emits a series of high frequency spurious pulses at the rate of the
control signal, and
- a device for receiving the high frequency spurious pulses
comprising means for reconstituting the control signal.
According to one embodiment, the device comprises
means for supplying to the switch means a data-bearing
control signal.
According to one embodiment, the device comprises
means for supplying to the switch means a coded control
signal.
According to one embodiment provided for an
electricity distribution network carrying an alternating
voltage, the receiving device comprises means for monitoring
the amplitude of the alternating voltage, supplying a
signal for authorizing pulse emitting having a determined
value when the alternating voltage is in the vicinity of
its peak value, and means for only closing the switch when
the signal for authorizing pulse emitting has the
determined value.
According to one embodiment, the monitoring means
supply a signal for authorizing pulse emitting having the

determined value when the amplitude of the alternating
voltage is at least equal to 50% of its peak value.
According to one embodiment, the monitoring means
comprise a rectifier supplying a single- or full-wave
rectified voltage the amplitude of which is representative
of the amplitude of the alternating voltage, and a
comparator receiving a reference voltage at one input and
the rectified voltage at another input, supplying the
signal for authorizing data sending.
According to one embodiment, the means for supplying
the control signal supply a control signal consisting of
pulses of constant duration for closing/opening the switch
means, each pulse comprising a rising edge and/or a high
level causing a change in the open or closed state of the
switch and a falling edge and/or a low level causing a
reverse change in the state of the switch.
According to one embodiment, the means for supplying
the control signal supply closing/opening pulses of a
duration at least less than l/8th of the period of the
alternating voltage.
According to one embodiment, the electric element is
a capacitor, a resistance, a light-emitting diode or a
combination of at least two of these elements.
According to one embodiment, the switch means is a
triac, a MOS transistor or a relay.
According to one embodiment, the control signal is
supplied by a microcontroller or a microprocessor.
According to one embodiment, the pulse-emitting
device comprises means for measuring current and is
arranged for sending a piece of information, in the form of
high frequency spurious pulses, relating to a current
measured.
According to one embodiment, the receiving device
comprises means for filtering, rejecting or ignoring
spurious pulses so as not to take these pulses into account
when reconstituting the control signal.

According to one embodiment provided for an
electricity distribution network carrying an alternating
voltage, the receiving device comprises means for supplying
a signal mirroring the alternating voltage, and means for
high-pass filtering the mirroring signal, to extract the
high frequency spurious pulses therefrom.
According to one embodiment, the receiving device
comprises an antenna for detecting the high frequency
spurious pulses by using an electromagnetic component of
the spurious pulses.
According to one embodiment, the receiving device
comprises means for sampling the signal received, and means
for analyzing the samples of the signal received, to detect
the presence of high frequency spurious pulses.
The present invention also relates to a circuit-
breaking device having a closed state and an open state,
and a pulse-emitting device according to the present
invention, for emitting a determined series of pulses when
the circuit-breaking device is in the open state.
According to one embodiment, the device comprises a
switch with pilot light that switches from the open state
to the closed state when the circuit-breaking device
switches from the closed state to the open state, and all
or . part of the pulse-emitting device is electrically
powered through the switch with pilot light, such that the
pulse-emitting device is inactive while the circuit-breaker
is in the closed state.
These and other objects, features and advantages of
the present invention will be explained in greater detail
in the following description of the method according to the
present invention and of various examples of application
described in the form of devices implementing the method,
given in relation with, but not limited to the accompanying
drawings, in which:
- Figure 1 represents the appearance of a high frequency
spurious pulse,

- Figure 2 schematically represents a device implementing
the method according to the present invention,
- Figures 3A, 3B are timing diagrams showing, in a general
manner, the method according to the present invention,
Figure 3C represents the waveform of a voltage
distributed by an electricity distribution network,
- Figures 3D, 3E are timing diagrams of signals showing a
first embodiment of the method according to the present
invention,
- Figure 4A represents, with an expanded time scale, the
waveform of a voltage distributed by an electricity
distribution network,
- Figures 4B, 4C are timing diagrams of signals showing a
second embodiment of the method according to the present
invention,
Figure 5 is the wiring diagram of an example of
embodiment of a pulse-emitting device according to the
present invention,
- Figure 6 represents in block form another example of
embodiment of a pulse-emitting device according to the
present invention, and
- Figure 7 represents in block form a circuit-breaker
according to the present invention.
Figure 1 represents the appearance of a spurious
pulse I emitted naturally by an electric element when it is
switched on. Such a spurious pulse is independent of the
electricity consumption of the electric element and takes
the shape of a high frequency alternating wave train,
typically of a frequency in the order of 20 MHz. The
duration of this spurious pulse is of several hundreds of
nanoseconds, typically 250 nanoseconds. Its amplitude U
can range from about ten millivolts to several Volts (under
a voltage of 220 Volts) according to the reactive component
of the element and the power it absorbs. Upon receipt, due
to the limitations of the bandwidth of the measuring
channels (measurement equipment and distribution network),
the pulses collected are broader and in the order of about

ten microseconds, i.e. a broadening by a factor 40 of the
initial pulse.
As indicated above, the present invention proposes
controlling by an electric element, the emission of high
frequency spurious pulses, to obtain a series of pulses
having a sought profile, instead of artificially
reproducing such pulses.
Figure 2 shows the method according to the present
invention. An electric element 1 is linked through a
switch 2 to an electricity distribution network 3 carrying
an alternating voltage Uac. The network 3 is here single
phase and the electric element 1 is linked to the phase
wire (PH) and to the neutral wire (NL) of the network, the
switch 2 being interposed between the phase wire and the
corresponding terminal of the electric element. The switch
2 comprises a control terminal to which a control signal CS
is applied that controls the closing and the opening of the
switch.
The switch 2 is of any appropriate type, for example
a monostable switch of normally open type (MOS or bipolar
transistor, monostable relay...) or a bistable switch
(triac, bistable relay...).
The element 1 can be any type of electric element
producing spurious pulses of desired form (duration,
amplitude...), such as an electric bulb, a light-emitting
diode (LED), a capacitor, a high value resistance or a
combination of these elements for example. The electric
element preferably has a high impedance to avoid the
appearance of a high switching current on the network. The
electric element is for example a 250V capacitor of low
value (C) having a high impedance Z (Z=l/2ηFC) at the
frequency (F) of the voltage Uac, generally 50 or 60 Hz.
The control signal CS is a signal with two states "1"
and "0", the "1" corresponding to a determined control
voltage and the "0" corresponding to another determined
control voltage, that can be the ground potential.
Conventionally, it is considered that the switch is closed

(on) when the signal CS is on 1 (monostable switch) or when
the signal CS changes from 0 to 1 (bistable switch) and
that the switch is open (off) when the signal CS is on 0 or
changes from 1 to 0. As will be seen below, the signal CS
is capable of being applied directly to the control
terminal of the switch or through a driver stage. Thus,
within the meaning of the present invention, the signal CS
represents the logic control signal of the switch. It can
constitute the primary control signal of the switch, i.e.
the signal that is effectively applied to the control
terminal of the switch, if it is compatible with the
electrical characteristics of this control terminal.
In summary, the method according to the present
invention is based on the emission of high frequency pulses
designated here and in the claims as being "spurious"
pulses, to distinguish them from pulses produced
artificially. However, the term "spurious" does not mean
that the method according to the present invention produces
interference and is therefore incompatible with the
legislation aiming to regulate pollution on electric
networks. On the contrary, due to the very short duration
of the spurious pulses, the method according to the present
invention is less "intrusive" and less interfering than
classical methods based on the injection of a carrier
signal into the electric network or the injection of capacitor
discharge pulses.
Figures 3A, 3B, 3C show the method according to the
present invention in greater detail. Figure 3A represents
an example of any shape of signal CS and Figure 3B
represents the amplitude, in Volts, of the high frequency
spurious pulses produced on the network 3. Figure 3C
represents the waveform of the voltage Uac at the moment at
which the spurious pulses are emitted. Upon each change
from the state 0 to the state 1 of the signal CS, the
switch 2 becomes on, the electric element 1 receives the
voltage Uac and a closing spurious pulse I1, I3, I5 (or
connection pulse) is emitted. Upon each change from the

state 1 to the state 0 of the signal CS, the switch 2
changes into the open state (OFF) , the element 1 is
disconnected from the network and an opening spurious pulse
12, 14, 16 (or disconnection pulse) is emitted.
By jointly observing Figures 3B and 3C, it can be
seen that the amplitude of the spurious pulses is not
constant and depends, in particular, on the moments at
which these pulses are emitted. More particularly, the
following experimental observations have been made:
- Observation No. 1: the amplitude of the closing or
opening spurious pulses depends on the amplitude of the
voltage Uac at the moment at which the closing or the
opening of the switch occurs,
Observation No. 2: in similar emission conditions,
certain spurious pulses, here the (disconnection) opening
spurious pulses, can have an amplitude below that of the
closing spurious pulses and not exceeding 10% of the
amplitude of the closing spurious pulses.
Thus, in accordance with Observation No. 1, it can be
seen in Figure 3B that the closing spurious pulse I1 is
maximal since it is emitted at an instant t1 at which the
voltage Uac is equal to its peak value Umax (a spurious
pulse of same amplitude would be obtained with the peak
value -Umax). Furthermore, the closing spurious pulses I3,
I5 are emitted at instants t3, t5 at which the voltage Uac
has a low amplitude, and have an amplitude much lower than
that of the pulse I1. Similarly, the opening spurious
pulse 14 is emitted at an instant t4 at which the voltage
Uac is below its peak value Umax or -Umax, and has an
amplitude below that of the opening spurious pulse I2. In
accordance with Observation No. 2, it can be seen that the
opening spurious pulse I2, although emitted at an instant
t2 at which the voltage Uac is maximal (i.e. in the same
conditions) , has an amplitude clearly below that of the
spurious pulse I1. Finally, the opening spurious pulse I6
is emitted at an instant t6 at which the voltage Uac is
maximal (-Umax) and has an amplitude higher than those of

the closing spurious pulses I3, I5 that are emitted in
unfavorable conditions, despite the fact that they would
have a higher amplitude if they were emitted in the same
conditions.
In one embodiment of the present invention based on these
observations, the following rules are applied:
1) The opening spurious pulses are not considered
here to be "exploitable", as they have an amplitude that is
too low relative to the closing spurious pulses. Thus,
these pulses are neutralized upon emission, or rejected
upon receipt in a manner described below.
2) The closing spurious pulses are emitted when the
voltage Uac is close to the maximum value, i.e. when the
voltage Uac has an amplitude higher than or equal to x% of
the value Umax, x being a parameter to be defined
experimentally and preferably at least equal to 50.
Figures 3D, 3E show a first embodiment of the method
wherein the opening spurious pulses are neutralized upon
emission. Figure 3D represents the shape of the signal CS
and Figure 3E represents the amplitude of the pulses
obtained. The signal CS is synchronized with the waveform
of the voltage Uac, represented in Figure 3C. More
particularly, the signal CS changes to 1 when the voltage
Uac is equal to Umax or -Umax and changes to 0 when the
voltage Uac is zero. In other terms, the switch 2 changes
from the closed state to the open state when the voltage
Uac is zero and the opening spurious pulses are never
emitted, as can be seen in Figure 3E. However, the
amplitude of the closing spurious pulses is maximal since
the switch is only closed at the instants at which the
voltage Uac is maximal.
It will be understood that the profile of signal CS
represented in Figure 3D only constitutes a template
determining the authorized instants of closing and opening
of the switch 2. Thus, various series of pulses each
having their own profile can be emitted, and each profile
can be allocated to the identification of a determined

electric appliance, as was considered by EP 1,136,829 but
by using synthesis pulses.
According to one aspect of the present invention,
this template is used to transmit data. For example, as
shown in Figure 2, data DTx to be sent, possibly in coded
form, are applied to a circuit 4 that supplies the control
signal CS while monitoring the voltage Uac. The data can
be sent bit by bit or as a frame comprising for example one
start bit and 8 data bits, and possibly a signature field,
for example a parity bit. In the absence of coding, a
closing of the switch 2 (i.e. the emission of a spurious
pulse) corresponds to sending a bit on 1, while the absence
of closing of the switch at the moment imposed by the
template, i.e. an absence of any spurious pulse,
corresponds to sending a bit on 0.
In a network 50Hz, the period T of the voltage Uac is
of 20 ms, such that 100 spurious pulses (i.e. 100 non-coded
bits) can be sent in one second. Although this pulse rate
is slow, it is sufficient for certain identification or
data transmission applications, particularly an application
to the management of a stock of streetlights described
below.
A second embodiment of the method is provided for
sending data or trains of pulses with a higher rate. This
embodiment is shown by Figures 4A, 4B, 4C. Here, the
closing spurious pulses are not neutralized upon emission
and are ignored upon receipt, thanks to an adequate setting
of a detection threshold. To determine the instants for
authorizing the emission of the spurious pulses, a
threshold U1 close to the peak value Umax is chosen, for
example a threshold equal to 0.66 Umax. As represented in
Figure 4A, this threshold enables two time windows for
authorizing emission TW1, TW2 to be defined, at each half-
period T/2 of the voltage Uac. The window TW1 encompasses
the values of the voltage Uac that are positive and higher
than U1 and the window TW2 encompasses the values of the
voltage Uac that are negative and lower than -U1 (i.e.

higher than U1 in absolute value). Figure 4B represents
the template of the control signal CS. The latter
comprises trains of closing/opening pulses that are applied
to the switch 2 inside each time window TW1, TW2. As can
be seen in Figure 4C, each closing/opening pulse causes the
emission on the network of two high frequency spurious
pulses, i.e. a closing spurious pulse upon the rising edge
of the closing/opening pulse and an opening spurious pulse
upon the falling edge of the closing/opening pulse. As
indicated above, the opening spurious pulses are of an
amplitude much lower than that of the closing spurious
pulses and are destined to be filtered upon receipt.
With a voltage Uac of frequency 50 Hz, the duration
of the windows TW1, TW2 is in the order of 6 to 7 ms and
the number of closing/opening pulses that can be sent is
high. Thus, if each closing/opening pulse causes the
emission of two high frequency spurious pulses of a
duration in the order of 10 microseconds each (pulse width
upon receipt, useful signal), the minimum duration of each
closing/opening pulse must be at least equal to twice the
duration of the spurious pulses, i.e. in the order of 10 to
20 microseconds. In these conditions, by choosing this
minimum pulse duration as a template, and without taking
into account any limitations of the switch in terms of
switching frequency, each time window can contain
approximately 300 closing/opening pulses and thus offers a
high data rate relative to the first embodiment of the
method of the present invention, in the order of 30,000
pulses per second.
As above, the data can be sent in raw form, one bit
then corresponding to one pulse, or coded by any
appropriate coding protocol, one bit then corresponding to
several pulses. The data, whether coded or not, can be
sent in the form of individual bits or as a frame
comprising a start of frame field, a data field, and
possibly an end of frame field that can comprise a
verification field of CRC or parity type.

It will be understood by those skilled in the art
that various alternative embodiments and applications of
this method are possible. For example, the emission of the
high frequency spurious pulses can be provided only once
per period instead of twice per period, for example when
the voltage Uac is equal to +Umax (first embodiment) or is
higher than +U1 (second embodiment).
Figure 2 also schematically represents two examples
of embodiment of pulse detectors 10, 15 according to the
present invention.
The detector 10 is an inductive reception device the
operating principle of which has already been described in
EP 1,136,829. It comprises an input transformer for
extracting from the voltage Uac a mirroring signal that is
analyzed to detect the high frequency spurious pulses. The
transformer can be simply formed by a coil 11 arranged
around the phase wire (PH) of the network, at a source
point of the distribution of the current, for example near
an electricity meter. The coil supplies the mirroring
signal that is applied to a high-pass filter 12 to remove
its low frequency alternating component. The output of the
filter is applied to a sample hold analog-to-digital
converter 13 ("sample hold AD converter") that supplies
digital samples of the filtered voltage Uac, in
synchronization with a sampling period defining an
observation window. The choice of the sampling period and
of the duration of the observation window depends on the
period of emission of the high frequency spurious pulses,
i.e. the period between two closing/opening pulses. If the
spurious pulses are emitted with a high frequency, in
accordance with the second embodiment of the method of the
present invention, the observation window is chosen to be
sufficiently short to obtain a fineness of analysis
enabling the pulses to be differentiated within the pulse
trains emitted. The analysis of the samples of the voltage
Uac is performed by an analysis circuit 14, generally a
specific logic circuit, which analyzes the amplitude of the

samples received and detects the pulses of an amplitude
above the threshold for rejecting the closing spurious
pulses, so as to keep only the opening spurious pulses.
The circuit 14 thus reconstitutes the control signal CS,
and also deduces therefrom the data DTx when the signal CS
is data bearing. If they are received in coded form, the
data DTx can also be decoded by the circuit 14.
The detector 15 is a contactless device comprising an
antenna 16, an antenna booster 17 and a high-pass filter 18
for removing the signals of frequency below that of the
pulses to be detected. In addition to these elements, as
above, a sample hold AD converter 13 and an analysis
circuit 14 are provided. This embodiment of a pulse
detector according to the present invention is based on the
fact that the high frequency spurious pulses are found both
as electric pulses on the network and as electromagnetic
pulses that can be detected in the same way as any radio
frequency signal. The detector 15 is preferably arranged
near the pulse-emitting equipment, such as in the premises
in which the equipment is installed for example.
Figure 5 represents one simple and inexpensive
embodiment of a pulse-emitting device 20 according to the
present invention, intended to be installed in appliances
or electric equipment.
The device 20 comprises two terminals T1, T2 for
connection to the electricity distribution network 3, a
switch circuit 30, an electric supply circuit 40, a circuit
50 for monitoring the alternating voltage Uac and a control
circuit 60. The terminal Tl is connected to the phase wire
(PH) and the terminal T2 connected to the neutral wire (NL)
of the network 3. In accordance with the method of the
present invention, the switch circuit 30 comprises an
electric element 31, here a capacitor, and a switch 32.
The switch 32 is for example a triac or a MOS transistor (a
triac being represented in Figure 5). The switch 32 has
one terminal connected to the terminal Tl, another terminal
connected to one terminal of the capacitor 31, and a

control terminal (trigger of the triac or gate of the MOS
transistor) driven by the control circuit 60. The other
terminal of the capacitor 31 is connected to the terminal
T2.
The supply circuit 40 comprises a diode bridge
rectifier 41 having two input terminals connected to the
terminals I1, I2 through resistances 42, 43, a terminal
linked to the ground and an output terminal supplying a
full-wave rectified voltage Ur. The voltage Ur is applied
to one input of an adjusting assembly 46 that is linked to
the ground through an overvoltage clipper diode 44 and a
smoothing capacitor 45. The output of the adjusting
assembly 46 is linked to a stabilization capacitor 47 and
supplies a voltage Vcc for supplying the circuits 50, 60.
The monitoring circuit 50 comprises a diode rectifier
bridge 51 having two input terminals connected to the
terminals I1, I2 through resistances 52, 53, respectively,
a terminal linked to the ground and an output terminal
supplying a full-wave rectified voltage Ur'. The rectified
voltage Ur1 is applied to the positive input of a
differential amplifier 56 that is linked to the ground
through an overvoltage clipper diode 54 and a load resistor
55. The negative input of the amplifier 56 receives a
reference voltage Vref supplied by the mid-point of a
potentiometer 57 the anode of which receives the voltage
Vcc and the cathode of which is grounded. The differential
amplifier 56, here operating as a comparator, supplies a
signal ENB ("Enable") that is on 1 (Vcc) when the full-wave
rectified voltage Ur1 is higher than the reference voltage
Vref, and is on 0 (ground) in the opposite case. The
potentiometer 57 enables the voltage Vref to be adjusted so
as to define the width of the emission-authorizing time
windows TW1, TW2. By increasing the voltage Vref, the
width of the windows decreases and two authorization
instants are finally obtained corresponding to Uac=Umax and
Uac=-Umax, corresponding to the implementation of the first
embodiment of the method according to the present invention

(i.e. one pulse per half-period of the voltage Uac) . It
will be noted that the monitoring circuit 50 may comprise
only a single-wave rectifier if pulses are only to be
emitted on one of the two half-periods of the voltage Uac.
The circuit 60 supplies the control signal CS applied
to the control terminal of the switch 32. The circuit 60
comprises an inexpensive microcontroller 61, incorporating
on the same silicon microchip a microprocessor and its
input/output ports P0, P1, P2, P3. . ., a program memory,
data memories, a quartz oscillator... The port P0 receives
the signal ENB, the port P1 supplies the control signal CS,
and the ports P2 P3 are, optionally, used as ports for
communicating with the microcontroller for test,
maintenance, programming or other operations and are linked
to auxiliary terminals ATI, AT2 of the device 20.
The microcontroller detects the change to 1 of the
signal ENB by polling the port P0 or by interruption
declared on this port. The port P1 drives the switch 32
through a driver stage comprising a control block 62 and a
transistor 63. The control block 62 has an output
connected to the control terminal of the switch 32 and an
input connected to the collector of the transistor 63, the
emitter of which is connected to the ground and the base of
which receives the control signal CS.
Once on-board an appliance, the device 20 can be used
to transmit data or, more simply, to emit a series of non
data-bearing pulses, having an invariable predetermined
profile, used for example to identify the electric
appliance. In this last case, the circuit 60 can be a
logic circuit with a basic architecture, comprising a
synchronization input receiving the signal ENB and
supplying the control signal CS. By providing a
microcontroller or microprocessor, it is possible to
implement more complex applications requiring processing
and transmitting data, as will be seen in the examples of
applications described below.

Thus, various applications of the device 20 are
possible. One example of an application is the control of
streetlights in a built-up area. To that end, each
streetlight is equipped with such a device and cyclically
sends a piece of information about its on or off state.
This piece of information can be sent at low rate in
accordance with the first embodiment of the method of the
present invention, since it is in no way urgent and can be
processed over periods of time of several minutes. With a
reasonable investment, hundreds of streetlights can be
equipped with devices according to the present invention.
By giving each streetlight one second every minute to emit
pulses representative of the state of the streetlight, 60
streetlights can send information in one minute. A
reception unit arranged at a source point of the urban
electricity distribution network or at a bypass node, is
sufficient to receive the information sent by a plurality
of streetlights.
Various alternative embodiments of the pulse-emitting
device according to the present invention can, furthermore,
be made according to the intended applications.
Figure 6 represents a device 20' that comprises, in
addition to the circuits 30, 40, 50 and 60 that have just
been described, a current sensor 70 linked to a measuring
circuit 71. The measuring circuit 71 sends the control
circuit 60 data relating to current measurements taken by
means of the sensor 70. The microcontroller of the device
60 analyzes the results of the measurements and decides
whether or not to send them according to what is provided
in the application program loaded into its program memory.
This program can for example provide for the
microcontroller to send a piece of information on the
network relating to the current measured solely when the
latter changes from 0 to a non-zero value, then changes
from one consumption bracket to another, for example from
the bracket ranging from 0 to 1 A to the bracket ranging
from 1 to 2 A, from the bracket ranging from 1 to 2 A to

the bracket ranging from 2 to 3 A, etc. This piece of
information can take the shape of an eight-bit word (byte)
having a first value when the current measured changes from
0 to a non-zero value, then a second value when the current
changes from the bracket 0-1 A to the bracket 1-2 A, etc.
The device 20' can be arranged in an electric plug,
particularly a piggyback plug used to electrically supply
one or more appliances, or be installed on-board an
electric appliance, so as to measure the current passing
through the electric plug or the current consumed by the
appliance in which it is installed. Such an application
enables the method of measuring the electricity consumption
of electric appliances described by EP 1,136,829 to be
perfected. Indeed, when the current changes from 0 to a
non-zero value, the emission of the first byte enables the
appliance or the group of appliances that is switched on to
be identified on the network. Then, the emission of bytes
in relation with the change in consumption bracket enables
the consumption and locating measurements taken on the
network in the manner proposed by EP 1,136,829 to be
confirmed.
Another example of application of the method and
device according to the present invention will now be
described.
Many industrial installations comprise circuit-
breakers grouped together in electric cabinets, the closed
(switched on) or open (tripped) state of which must be
monitored. To that end, in the current state of the
technique, circuit-breakers have been developed that are
equipped with a switch with pilot light which, through a
mechanical actuator, switches from the open state to the
closed state when the circuit-breakers trip. Thus, in such
installations, the many circuit-breakers arranged in
electric cabinets each have a switch with pilot light
linked by two wires to a centralizer, which monitors the
state of the circuit-breakers to detect power failures.

The present invention proposes removing the
quantities of electric wires linking the switches with
pilot light to the centralizer, by installing on-board a
circuit-breaker a device according to the present invention
that is arranged to monitor the state of the circuit-
breaker and to send a piece of information when the
circuit-breaker is in the open state. This piece of
information can for example consist in a code for
identifying the circuit-breaker, the simple emission of
which means that the circuit-breaker has tripped.
Figure 7 represents an example of embodiment of a
circuit-breaker 90 according to the present invention,
comprising a combination of a classical circuit-breaker 80
and a device 20 according to the present invention. The
structure of the device 20 is identical to the one
described in relation with Figure 5 and will not be
described again. The circuit-breaker 80 comprises input
terminals T3, T4 connected to the phase and neutral wires
of the upstream part of the electricity distribution
network, and output terminals T5, T6 connected to the phase
and neutral wires of the downstream part of the electricity
distribution network. The circuit-breaker 80 also
comprises control terminals T7, T8 linked to the terminals
of a switch with pilot light 81. The terminals T1 and T2
of the device 20 are connected to the terminals T3 and T4
of the circuit-breaker 80 such that the device 20 is
electrically powered when the circuit-breaker is in the
open state.
The detection by the device 20 of the state of the
circuit-breaker 80, is here performed by means of the
switch with pilot light. Such a detection can be performed
in various ways. For example, the microcontroller of the
control circuit 60 can comprise two input/output ports
connected to the terminals T7, T8 to cyclically monitor the
on or off state of the switch with pilot light. However,
this solution has the disadvantage that the device 20 must

permanently be switched on, and implies consuming
electricity.
One advantageous solution, represented in Figure 7,
is that the supply voltage Vcc supplied by the circuit 40
is applied to the monitoring circuit 50 and to the control
circuit 60 through the switch with pilot light 81. Thus,
the device 20 stays switched off while the circuit-breaker
is in the triggered state. When the switch with pilot
light 81 closes, the circuits 50, 60 are electrically
powered and the control circuit 60 implicitly "knows", when
it is switched on, that a piece of information must be sent
on the electric network. The control circuit 60 is
therefore simply programmed for emitting, when it is
switched on, a series of pulses enabling the circuit-
breaker to be identified. Generally speaking, the
integration of the device 20 into a circuit-breaker 80 to
obtain the circuit-breaker 90 according to the present
invention involves only a minor increase in the cost price
of the circuit-breaker, and enables, in return, substantial
savings to be made on wiring as a result of removing the
electric wires linking the centralizer and the circuit-
breakers. A pulse receiver of the type described above
enables a wireless centralizer to be produced that is
capable of managing hundreds of circuit-breakers and of
supplying in real time an indication about the circuit-
breakers that are in the tripped state.
In the light of the examples described, it will be
understood by those skilled in the art that various other
alternative embodiments and applications of the present
invention are possible. In particular, although various
applications of the method of the present invention to an
electricity network carrying an alternating voltage have
been described, the present invention is also applicable to
direct current networks, particularly the 400V DC networks
used in industry or on board ships, the 200V DC networks,
including the low voltage 12V DC networks present in motor
vehicles. In particular, the method according to the

present invention can be used to cause a vehicle device
(such as a car headlamp for example) to send a piece of
information about its state (on, off, out of order, etc.) .
In the applications to direct current networks, the
monitoring of the waveform of the voltage carried by the
network is no longer necessary since as this voltage is
direct, it always has an optimal value for the emission of
the high frequency spurious pulses.
As the present invention is based on a phenomenon little
studied until now, it lies with those skilled in the art to complete
the teaching that has just been described by experimental
observations. Thus, further experiments have revealed that the
amplitude of the connection spurious pulses can prove to be equal or
even greater than that of the disconnection spurious pulses. This
can particularly be observed by using as electric element a low-
value resistor, for example of a few ohms, which is cyclically
connected to the network with a very short connection time, for
example a few microseconds, and which is thus passed through by a
high current, for example several amperes, that does not interfere
with the network due to its short duration. It can then be seen
that the amplitude of the spurious pulses emitted when the resistor
is disconnected from the network is substantially greater than that
of the spurious pulses emitted when the resistor is connected to the
network. In this case, the disconnection pulses can also be used as
means of transmitting a piece of information, instead of the
connection pulses. Furthermore, both types of connection and
disconnection pulses can be detected to obtain a redundant piece of
pulse detection information enabling the control signal to be
reconstituted with greater reliability.

WE CLAIM :
1. A method for transmitting a piece of information
through an electricity distribution network (3) carrying a
voltage (Uac), comprising the steps of:
- connecting, between two wires of the network, an electric
element (1, 31) in series with a switch means (2, 32),
- applying to the switch means a control signal (CS) of determined
shape so that the switch means is closed and opened successively,
- detecting the spurious pulses that appear in the network when the
switch means is closed or open, each spurious pulse comprising a
high frequency wave train, and
- reconstituting the control signal (CS).
2. Method as claimed in claim 1, wherein the switch
means (2, 32) is driven by a control signal (CS) bearing
data (DTx), such that data-bearing high frequency spurious
pulses are emitted at the rate of the control signal.
3. Method as claimed in claim 2, wherein the control signal
(CS) is a coded signal.
4. Method as claimed in one of claims 1 to 3, wherein
the electricity distribution network (3) carries an
alternating voltage (Uac) and wherein the control signal
(CS) is synchronized with the waveform of the alternating
voltage (Uac), so that the switch (2, 32) is only closed
when the alternating voltage is in the vicinity of its peak
value (Umax, -Umax).
5. Method as claimed in claim 4, wherein the
alternating voltage (Uac) is considered to be in the
vicinity of its peak value when it has an amplitude (U1,
U2) at least equal to 50% of its peak value.
6. Method as claimed in one of claims 4 and 5,
wherein the control signal (CS) is synchronized with the

waveform of the alternating voltage so that the switch is
only open when the alternating voltage is in the vicinity
of zero.
7. Method as claimed in one of claims 1 to 6, wherein
the control signal (CS) consists of pulses of constant
duration for closing/opening the switch means, each
closing/opening pulse comprising a rising edge and/or a
high level causing a change in the open or closed state of
the switch and a falling edge and/or a low level causing a
reverse change in the state of the switch.
8. Method as claimed in claim 7, wherein the control
signal comprises closing/opening pulses of a duration less
than l/8th of the period of the alternating voltage.
9. Method as claimed in one of claims 1 to 8, wherein
the electric element is a capacitor, a resistance, a light-
emitting diode or a combination of at least two of these
elements.

10. Method as claimed in one of claims 1 to 9,
wherein spurious pulses are neutralized, rejected or ignored,
and are not taken into account to reconstitute the control signal.
11. Method as claimed in claim 10, wherein the
detection of the spurious pulses comprises the production
of a signal mirroring the voltage carried by the
electricity distribution network, the high-pass filtering
of the mirroring signal, the sampling of the mirroring
signal according to a determined sampling window, for
obtaining digital samples of the mirroring signal, and the
analysis of the samples of the mirroring signal.
12. A method for remotely measuring the local
electricity consumption of an electric appliance connected

to an electricity distribution network carrying a
determined voltage, comprising the steps of:
- measuring the electricity consumption of the appliance by
means of an on-board current sensor, and
transmitting a piece of information through the
electricity distribution network in accordance with the
method as claimed in one of claims 2 to 11.
13. A method for identifying an electric appliance
connected to an electricity distribution network (3)
carrying a determined voltage (Uac), comprising a step of
transmitting a piece of information through the electricity
distribution network in accordance with the method as
claimed in one of claims 1 to 11, wherein the piece of
information is transmitted as a series of high frequency
spurious pulses forming a code for identifying the device.
14. Method as claimed in claim 13, wherein the
electric appliance is a circuit-breaker, and wherein the
transmission of the identification code is only triggered
when the circuit-breaker has tripped.
15. A device for sending and receiving a piece of
information via an electricity distribution network (3)
carrying a voltage (Uac), comprising:
- a pulse-emitting device (20, 20') for emitting pulses on the
network (3) comprising:
- an electric element (31) and a switch means in series,
connected between two wires (PH, NL) of the network, and
- means (60, 61) for applying to the switch means a control
signal (CS) of determined shape so that the switch means is
closed and opened successively, and
- a device (10, 15) for detecting spurious pulses that appear in the
network once the switch means is closed or opened, each spurious
pulse comprising a high frequency wave train, the detecting device
comprising means (12, 13, 14, 16, 17) for reconstituting the control
signal (CS).

16. Device as claimed in claim 15, comprising means
(61) for supplying the switch means with a data-bearing
control signal (CS).
17. Device as claimed in claim 16, comprising means
(61) for supplying to the switch means a coded control
signal (CS).
18. Device as claimed in one of claims 15 to 17,
provided for an electricity distribution network carrying
an alternating voltage (Uac), wherein the pulse-emitting
device comprises means (50) for monitoring the amplitude of
the alternating voltage (Uac), supplying a signal (ENB) for
authorizing pulse emitting having a determined value when
the alternating voltage is in the vicinity of its peak
value (Umax, -Umax), and means for only closing the switch
when the signal for authorizing pulse emitting has the
determined value.
19. Device as claimed in claim 18, wherein the
monitoring means (50) supply a signal for authorizing pulse
emitting having the determined value when the amplitude of
the alternating voltage is at least equal to 50% of its
peak value.
20. Device as claimed in one of claims 18 and 19,
wherein the monitoring means (50) comprise a rectifier (51)
supplying a single- or full-wave rectified voltage (Ur')
the amplitude of which is representative of the amplitude
of the alternating voltage (Uac), and a comparator (56)
receiving a reference voltage (Vref) at one input and the
rectified voltage (Ur') at another input, supplying the
signal (ENB) for authorizing data sending.
21. Device as claimed in one of claims 15 to 20,
wherein the means (60, 61) for supplying the control signal

supply a control signal (CS) consisting of pulses of
constant duration for closing/opening the switch means,
each pulse comprising a rising edge and/or a high level
causing a change in the open or closed state of the switch
and a falling edge and/or a low level causing a reverse
change in the state of the switch.
22. Device as claimed in claim 21 and one of claims
18 to 20, wherein the means (60, 61) for supplying the
control signal supply closing/opening pulses of a duration
at least less than l/8th of the period of the alternating
voltage.
23. Device as claimed in one of claims 15 to 22,
wherein the electric element is a capacitor (31), a
resistance, a light-emitting diode or a combination of at
least two of these elements.
24. Device as claimed in one of claims 15 to 23,
wherein the switch means is a triac (32), a MOS transistor
or a relay.
25. Device as claimed in one of claims 15 to 24,
wherein the control signal (CS) is supplied by a
microcontroller or a microprocessor (61).
26. Device as claimed in one of claims 15 to 25,
wherein the pulse-emitting device (20') comprises means
(70, 71) for measuring current and is arranged for sending
a piece of information, in the form of high frequency
spurious pulses, relating to a current measured.
27. Device as claimed in one of claims 15 to 26,
wherein the detecting device (10) comprises means (13, 14)
for filtering, rejecting or ignoring spurious pulses so as
not to take these pulses into account when reconstituting
the control signal.

28. Device as claimed in one of claims 15 to 27,
provided for an electricity distribution network carrying
an alternating voltage (Uac), wherein the detecting device
(10) comprises means for supplying a signal mirroring the
alternating voltage, and means (12) for high-pass filtering
the mirroring signal, to extract the high frequency
spurious pulses therefrom.
29. Device as claimed in one of claims 15 to 27,
wherein the detecting device (15) comprises an antenna (16)
for detecting the high frequency spurious pulses by using
an electromagnetic component of the spurious pulses.
30. Device as claimed in one of claims 28 and 29,
wherein the detecting device (10, 15) comprises means (13)
for sampling the signal received, and means (14) for
analyzing the samples of the signal received, to detect the
presence of high frequency spurious pulses.
31. A circuit-breaking device (90) having a closed
state and an open state, characterized in that it comprises
a pulse-emitting device (20) as claimed in one of claims 15
to 25, for emitting a determined series of pulses when the
circuit-breaking device is in the open state.
• 32. Circuit-breaking device as claimed in claim 31,
comprising a switch with pilot light (81) that switches
from the open state to the closed state when the circuit-
breaking device switches from the closed state to the open
state, and wherein all or part (50, 60) of the pulse-
emitting device (20) is electrically powered through the
switch with pilot light (81), such that the pulse-emitting
device is inactive while the circuit-breaker is in the
closed state.

ABSTRACT

Method And Device For Transmitting Information Through
A Power Distribution Network
A method for transmitting a piece of information
through an electricity distribution network (3) carrying a
voltage (Uac), comprising the steps of: connecting, between
two wires of the network, an electric element (1, 31) in
series with a switch means (2, 32), applying to the switch
means a control signal (CS) of determined shape so that the switch
means is closed and opened successively, detecting the spurious
pulses that appear in the network when the switch means is closed or
open, each spurious pulse comprising a high frequency wave train,
and reconstituting the control signal (CS).

"METHOD AND DEVICE FOR TRANSMITTING INFORMATION THROUGH A POWER DISTRIBUTION NETWORK"

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