Title of Invention

"A MOBILE RADIOWAVE RECEIVER WITH CONTROLLED AMPLIFYING GAIN AND DEMODULATION FILTER BANDWIDTH"

Abstract A mobile radio wave receiver including an automatic gain control amplifier, an electric field intensity detection circuit, an error correction circuit, and an error correction error detection circuit is disclosed. The automatic gain controlling is selectively effected in accordance with the detected electric field intensity and a degree of the detected error correction errors. The mobile radio wave receiver further includes a bandpass filter with a first variable bandwidth and a waveform shaping circuit with a second variable bandwidth, wherein the first and second variable bandwidths are controlled in accordance with the detected electric field intensity and the degree of the error correction errors.
Full Text The present invention relates to a mobile radio wave receiver. DESCRIPTION OF THE PRIOR ART
A mobile radio wave receiver including an automatic gain control circuit for controlling a gain of a high frequency amplifier is known.
Fig. 3 is a block diagram of such prior art a mobile radio wave receiver.
A reception signal from an antenna 1 is supplied to a high frequency amplifier 2 of which gain is controlled by an automatic gain control circuit 3. An output of the high frequency amplifier 2 is supplied to a frequency conversion circuit 4. The frequency conversion circuit 4 converts the output of the high frequency amplifier 2 into an intermediate frequency signal (IF signal) by one of mixers 42a and 42b supplied with local oscillation signals from local oscillators 41a and 41b and the converted signal is supplied to a demodulation circuit 5. The demodulation circuit 5 including a bandpass filter 6, a demodulation signal generation circuit 7, and a waveform shaping filter 8 generates and outputs a demodulated signal, wherein bandwidths of the bandpass filter 6 and the waveform shaping filter 8 are fixed.
The automatic gain control circuit 3 decreased the gain when the electric field is relatively high to prevent interdemodulation interference.
Recently, to quickly send a transmission signal to a reception antenna, a plurality of transmission signals having the same data have been transmitted from a plurality of transmission antennas, respectively. As a result, a plurality of signals having the same data and the almost same electric field intensity are received in a reception antenna of a conventional mobile radio wave receiver. In this case, the receiver is adversely influenced by fading such as a steep change in electric field intensity, and reception defect and/or the deterioration of communication quality occur in the receiver.
To prevent this problem, it is effective to stop the operation of an automatic gain control circuit or optimize filters of a demodulation circuit when the fading occurs. However, this countermeasure against the fading depends on fundamental performance in static electric field intensity such as reception sensitivity or resistance to intermodulation interference. Therefore, the receiver is designed while considering the fundamental performance.
An object of the present invention is to provide a mobile radio wave receiver in which the deterioration of communication quality is prevented not only in a radio wave condition of a changing electric field intensity caused by
the fading but also in any of radio wave conditions of a week electric field intensity and a static electric field intensity causing intermodulation interference by optimizing the operation of the receiver in any of the radio wave conditions of the changing electric field intensity, the week electric field intensity and the static electric field intensity.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior mobile radio wave receiver.
According to the present invention there is provided a mobile radio wave receiver comprising:
an antenna for receiving a radio waive signal with a desired component, the desired component having data and error correction code data;
a high frequency amplifier, connected to the antenna, for amplifying the radio wave signal received by the antenna with a gain;
an automatic gain control circuit, connected to the high frequency amplifier, for automatically setting the gain in accordance with a gain control signal;
a frequency conversion circuit, connected to the high frequency amplifier, for generating an intermediate frequency signal from an output of the high frequency amplifier;
a bandpass filter, connected to the frequency conversion circuit for bandpass-filtering the intermediate frequency signal generated by the frequency conversion circuit with a first variable bandwidth to detect said desired component;
a demodulation signal generating circuit, connected to the bandpass filter, for demodulating the intermediate frequency signal bandpass-filtered by the bandpass filter to generate a demodulation signal from the detected desired component; and
a waveform shaping filter connected to the demodulation signal generating circuit, for waveform-shaping the demodulation signal obtained in the demodulation signal generating circuit with a second variable bandwidth to detect said data and said error correction code data and outputting the detected data and the detected error correction code data
characterized in that the mobile radio wave receiver comprises:
an electric field detection circuit, connected to the bandpass filter, for detecting an electric field intensity of the radio wave signal from the intermediate frequency signal bandpass-filtered by the bandpass filter;
a filter control circuit (16), connected to the bandpass filter, for initially setting the first and second variable bandwidths of the bandpass filter and the waveform shaping filter in a narrow bandwidth condition; and
a control section, connected to the automatic gain control circuit, the filter control circuit and the electric field detection circuit, for comparing the electric field intensity detected by the electric field detection circuit with a reference holding the first and second variable bandwidths of the filter control circuit when the detected electric field intensity is not higher than a first reference, making the first and second variable bandwidths in a broad bandwidth condition when the detected electric filed intensity is higher than the first reference, and generating the gain control signal according to the detected data and the detected error correction code data output from the waveform shaping filter to make the automatic gain control circuit set the gain of a first gain value.
In the mobile radio wave receiver, the demodulation circuit includes a bandpass filter for bandpass-filtering the intermediate frequency signal with a first variable bandwidth to detect the desired component, a demodulation signal generation circuit for generating a demodulation signal from the detected desired component, and a waveform shaping filter with a second variable bandwidth for waveform-shaping the demodulation signal to output the detected data and the detected error correction code data, and the mobile radio wave receiver further comprises a bandwidth control circuit for making the first and second variable bandwidths in a narrow bandwidth condition when the detected electric field intensity is lower than the reference and making the first and second bandwidths in a wide bandwidth condition when the detected electric field
intensity is not lower than the reference.
The mobile radio wave receiver may further comprise: an error correction circuit for detecting and correcting errors in the detected data with the detected error correction code data to output error-corrected data and generating a pulse in response to each of the errors; a counter for counting the and outputting a count value; and a second comparing portion for comparing the count value with a second reference, wherein the control portion generates the gain control signal in accordance with the detected electric field intensity when the detected electric field intensity is not lower than the reference and the count value is higher than the second reference. In this case, the control portion may firstly generate the gain control signal indicative of a first gain control range when the detected electric field intensity is not lower than the reference and the count value is higher than the second reference and then, the control portion receives the comparing result from the second comparing portion and secondly generates the gain control signal indicative of a second gain control range, the first gain control range being higher than the second gain control
range.
BRIEF DESCRIPTION OF THEA ACCOMPAUYING RAWINGS
The object and features of the present invention
will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Fig. 1 is a block diagram of a mobile radio wave receiver of an embodiment of this invention;
Fig. 2 shows a flow chart of the embodiment showing an operation of the microprocessor 13 shown in Fig. 1; and
Fig. 3 is a block diagram of a prior art mobile radio wave receiver.
The same or corresponding elements or parts are designated with like references throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION
Hereinbelow will be described an embodiment of this invention.
Fig. 1 is a block diagram of a mobile radio wave receiver of an embodiment of this invention.
The mobile radio wave receiver of this embodiment comprises an antenna 10 for receiving a radio wave including a desired component including data and error correction code data, an RF circuit 11, including an high frequency amplifier 21 and frequency conversion circuit 22, for generating an intermediate frequency signal from an output of the antenna b, a demodulation circuit 12 including a bandpass filter 18, a demodulation signal generation circuit 19, a waveform shaping filter 20, and a
discriminator 23, for generating a demodulation signal from the intermediate frequency signal, an error correction circuit 131 for correcting the data in the demodulation signal and error correction errors in accordance with the error correction code data in the demodulation signal and outputting error-corrected data and an error correction error signal, an electric filed detection circuit 17 for detecting an electric field intensity of the desired component in the received radio wave signal from an output the bandpass filter 18 or the intermediate frequency signal, a counter 132 for counting the number of times of error-correction errors in the error correction circuit 131, a microprocessor 13 responsive to the electric field detection circuit 17 and the counter 132 for generating an automatic gain control data and filter control data, an automatic gain control circuit 14 for controlling the gain of the high frequency amplifier 21 in accordance with the automatic gain control data, and a filter control circuit 16 for controlling a bandwidth of the bandpass filter 18 and a bandwidth of the wave-shaping filter 20, that is, the bandwidth of the demodulation circuit 12 in accordance with the filter control data.
The antenna 10 receives the radio wave signal including the desired component. The RF circuit 11 includes the high frequency amplifier 21 for amplifying the
received radio wave signal with its gain controlled by the automatic gain control circuit 14 and the frequency conversion circuit 22 for generating the intermediate frequency signal from an output of the antenna 10 The frequency conversion circuit 22 includes a quadrature mixing circuit (not shown) and at least a local oscillator (not shown) for supplying a local oscillation signal to the quadrature mixing circuit.
The bandpass filter 18 effects bandpass-filtering the intermediate frequency signal with the bandwidth controlled to output a baseband signal. The demodulation signal generation circuit 19 effecting FM demodulation to output FM-demodulated signal. The waveform shaping filter 20 effects waveform-shaping the binary signal with it bandwidth controlled. The discriminator 23 discriminates the output of the waveform shaping filter 20 to supply at NRZ signal as the demodulation signal of the demodulation circuit 12 to the error correction circuit 131.
The error correction circuit 131 corrects data in the demodulation signal in accordance with error codes included in the demodulation signal and outputs the error-corrected received data.
The electric field detection circuit 17 detects the electric field intensity of the desired component of the received radio wave signal from an intermediate frequency
signal in the demodulation circuit 12. The counter 132 counts the number of times of error-correction errors in the error correction circuit 131. That is, the error correction circuit 131 outputs a pulse when error correction is impossible and the counter 132 counts the pulses.
The microprocessor 13 generates the automatic gain control data and the filter control data in accordance with the detected electric field intensity from the electric field detection circuit 17 and the count value from the counter 132 to generate the automatic gain control data and filter control data in accordance with a program stored in a ROM 13a provided therein.
The automatic gain control circuit 14 controls the gain of the high frequency amplifier 21 in accordance with the automatic gain control data from the microprocessor 13. The filter control circuit 16 generates the filter control signal to control the pass-band characteristics of the bandpass filter 18 and the wave-shaping filter 20. Then, the bandwidth of the demodulation circuit 12 is controlled in accordance with the filter control data from the microprocessor.
Fig. 2 shows a flow chart of this embodiment showing the operation of the microprocessor 13 shown in Fig. 1.
At first, it is assumed that the electric field
intensity is weak. Then, the microprocessor 13 effects an initial setting, that is, the automatic gain control is not effected, i.e., the gain of the high frequency amplifier is set to a predetermined value and the bandwidth of the demodulation circuit 12 (bandwidths of the bandpass filter 18 and the waveform shaping filter) is set to the narrow bandwidth in step stl. In the following step st2, the microprocessor 13 receives the detected electric field intensity data from the electric field detection circuit 17 and compares the detected electric field intensity data with a first reference REF1. If the detected electric field intensity data is not higher than the first reference REF1, that is, the electric field is weak, processing returns to step stl to hold the initial setting in step stl.
If the detected electric field intensity data is higher than the first reference REF1 in step st2, that is, the detected electric field intensity is strong, the microprocessor 13 generates the filter control data indicating a broad bandwidth to set the bandwidth of the demodulation circuit 12 to the broad band (broad bandwidth condition) in step st3.
In the following step st4, the microprocessor 13 receives the count data from the counter 132, that is, the number of times of error correction errors for a predetermined interval using a timer 13b provided therein
and compares the number of times of error correction errors with a second reference REF2. If the number of times of error correction errors is not higher than the second reference REF2, that is, the error correction errors are relatively few, processing returns to step st3 to hold the broad bandwidth condition of the demodulation circuit 12.
If the number of times of error correction errors is higher than the second reference REF2 in step st4, that is, the error correction errors are relatively frequent, the microprocessor 13 generates, in step st5, the automatic gain control data in an AGC1 mode, that is, the automatic gain control is effected within a first range which is higher than that of an AGC2 mentioned later.
In the following step st6, the microprocessor 13 receives the count data in the AGC1 mode from the counter 132 again, that is, the number of times of error correction errors for the predetermined interval while the automatic gain control is effected within the first range and compares the number of times of error correction errors with the second reference REF2. If the number of times of error correction errors is not higher than the second reference REF2, that is, the error correction errors are relatively few, processing returns to step st5 to hold the broad bandwidth condition of the demodulation circuit 12 and the automatic gain control in the AGC1 mode.
If the number of times of error correction errors is higher than the second reference REF2 in step st6, that is, the error correction errors are relatively frequent in the AGC1 mode, which is considered to be too higher electric field intensity, the microprocessor 13 generates, in step st7, the automatic gain control data in the AGC2 mode, that is, the automatic gain control is effected within a second range which is not higher than that of the AGC1 mentioned above.
In the following step st8, the microprocessor 13 receives the count data in the AGC2 mode from the counter 132 again, that is, the number of times of error correction errors for the predetermined interval in the AGC2 mode and compares the number of times of error correction errors with the second reference REF2. If the number of times of error correction errors is not higher than the second reference REF2, that is, the error correction errors are relatively few, processing returns to step st7 to hold the broad bandwidth condition of the demodulation circuit 12 and the automatic gain control in the AGC2 mode.
If the number of times of error correction errors is higher than the second reference REF2 in step st8, that is, the error correction errors are relatively frequent, processing returns to step stl because the condition may vary.
As mentioned above, according to this invention, the automatic gain controlling and the bandwidth controlling are effected in consideration of the electric field intensity and a degree of the error correction errors, so that even in a condition of a weak electric field intensity, in a condition of a strong electric field intensity, or in a variable electric field intensity, the receiving operation can be provided suitably.




WE CLAIM:
1. A mobile radio wave receiver comprising:
an antenna (10) for receiving a radio wave signal with a desired component, the desired component having data and error correction code data;
a high frequency amplifier (21), connected to the antenna (10), for amplifying the radio wave signal received by the antenna (10) with a gain;
an automatic gain control circuit (14), connected to the high frequency amplifier (21), for automatically setting the gain in accordance with a gain control signal;
a frequency conversion circuit (22), connected to the high frequency amplifier (21), for generating an intermediate frequency signal from an output of the high frequency amplifier (21);
a bandpass filter (18), connected to the frequency conversion circuit (22) for bandpass-filtering the intermediate frequency signal generated by the frequency conversion circuit (22) with a first variable bandwidth to detect said desired component;
a demodulation signal generating circuit (19), connected to the bandpass filter (18), for demodulating the intermediate frequency signal bandpass-filtered by the bandpass filter (18) to generate a demodulation signal from the detected desired component; and
a waveform shaping filter (20) connected to the demodulation signal generating circuit (19), for waveform-shaping the demodulation signal obtained in the demodulation signal generating circuit (19) with a
second variable bandwidth to detect said data and said error correction code data and outputting the detected data and the detected error correction code data
characterized in that the mobile radio wave receiver comprises:
an electric field detection circuit (17), connected to the bandpass filter (18), for detecting an electric field intensity of the radio wave signal from the intermediate frequency signal bandpass-filtered by the bandpass filter (18);
a filter control circuit (16), connected to the bandpass filter (18), for initially setting the first and second variable bandwidths of the bandpass filter (18) and the waveform shaping filter (20) in a narrow bandwidth condition; and
a control section (13; 131; 132), connected to the automatic gain control circuit (14), the filter control circuit (16) and the electric field detection circuit (17), for comparing the electric field intensity detected by the electric field detection circuit (17) with a reference holding the first and second variable bandwidths of the filter control circuit (16) when the detected electric field intensity is not higher than a first reference, making the first and second variable bandwidths in a broad bandwidth condition when the detected electric filed intensity is higher than the first reference, and generating the gain control signal according to the detected data and the detected error correction code data output from the waveform shaping filter (20) to make the automatic gain control circuit (14) set the gain of a first gain value.
2. The mobile radio wave receiver as claimed in claim 1, wherein the control section (13; 131; 132) comprises:
an error correction circuit (131) for detecting and correcting errors in the detected data with the detected error correction code data to output error-corrected data and generating a pulse in response to each of said errors;
a counter (132) for counting said pulses; and
a microprocessor (13) which performs a first comparison of the count value obtained by the counter with a second reference when the detected electric field intensity is higher than the first reference, generates another gain control signal to make the automatic gain control circuit (14) set the gain of a second gain value higher than the first gain value when the count value is higher than the second reference in the first comparison, holds the gain control signal to the first gain value when the count value is not higher than the second reference in the first comparison, performs a second comparison of the count value obtained by the counter and corresponding to the gain of the second gain value with the second reference after setting the gain of the second gain value in the automatic gain control circuit (14), generates still another gain control signal to make the automatic gain control circuit (14) set the gain of a third gain value lower than the second gain value when the count value is higher than the second reference in the second comparison, and
holds the gain control signal to the second gain value when the count value is not higher than the second reference in the second comparison.
3. A mobile radio wave receiver substantially as hereinbefore
described with reference to and as illustrated in the accompanying
drawings.

Documents:

737-del-1998-abstract.pdf

737-del-1998-claims.pdf

737-del-1998-complete specification (granded).pdf

737-del-1998-correspondence-others.pdf

737-del-1998-correspondence-po.pdf

737-del-1998-description (complete).pdf

737-del-1998-drawings.pdf

737-del-1998-form-1.pdf

737-del-1998-form-13.pdf

737-del-1998-form-19.pdf

737-del-1998-form-2.pdf

737-del-1998-form-3.pdf

737-del-1998-form-4.pdf

737-del-1998-form-6.pdf

737-del-1998-pa.pdf

737-del-1998-petition-138.pdf


Patent Number 197490
Indian Patent Application Number 0737/DEL/1998
PG Journal Number 37/2008
Publication Date 12-Sep-2008
Grant Date 16-Mar-2007
Date of Filing 23-Mar-1998
Name of Patentee MATSUSHITA ELECTRIC INDUSTRIAL CO. LTD.
Applicant Address 1006 OAZA KADOMA, KADOMA-SHI, OSAKA 571-0050, JAPAN.
Inventors:
# Inventor's Name Inventor's Address
1 KOUTARO YOSHIDA 77-5-306, KUNIMI 6-CHOME, AOBA-KU, SENDAI 981.
2 YOSHINORI OSAWA 6-10-22-102, TSUNASHIMA NISHI, KOHOKU-KU, YOKOHAMA 223.
3 NOZOMI KOH 2-9-1, NISHI ONUMA, SAGAMIHARA-SHI, KANAGAWA-KEN 229.
PCT International Classification Number H04B 1/06
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/049,381 1998-03-27 U.S.A.
2 98105184.7 1998-03-27 U.S.A.