Title of Invention

AN ECHO CONTROLLING APPARATUS AND METHOD IN A VIDEO CONFERENCING SYSTEM

Abstract

An echo controlling apparatus for a video conferencing system and an echo controlling method using the same. The echo controlling apparatus comprises a memory (34) for storing a far-end input signal, a near-end input signal and an estimated echo signal as initial parameters matching the circumstance of a video conferencing system of a conference room; an echo controller (30) for calculating an initial adaptive filter coefficient (30) for calculating an initial adaptive filter coefficient using the signals stored in the memory, and for updating the adaptive filter coefficient using new parameters input during a conference; and a controller (32) for reading the signals stored in the memory to provide the echo controller with the read signals.

Full Text

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an echo controlling apparatus of a video conferencing system, and more particularly, to an echo controlling apparatus of a video conferencing system using a personal computer (PC) and a control method using the same. 2. Description of the Related Art FIG. 1 is a block diagram illustrating a general video conferencing system. In FIG. 1, an audio signal of a.person taking part in video conferencing in a conference room A, generated via a first microphone 10, is transmitted to a second speaker 16 of a conference room B via a first echo controller 11, a transceiver 14, and a second echo controller 15. The audio signal output from the second speaker 16 is provided to a second microphone 18 after being echoed by a wall 17 of the conference room B or directly provided to the second microphone 18. Here, if the echo controllers 11 and 15 do not operate, the audio signal output from the second speaker 16 is fedback to a first speaker 12 of the conference room A via the second microphone 18 and the transceiver ZA . The feedback audio signal output from the f i ret speaker 12 is provided to the first mi rrophone 10 after being echoed by a wal1 13 of the conference room A or directly provided to the first: microphone 10. Thus, an echo phenomenon occurs in the conference room A, 1A where the person who has spoken in the conference room A can hear his own voice after a predetermined time. The function of the echo controllers will be described with reference to FIG. 2. Referring to FIG. 2, a far-end input signal Y which is an audio signal transmitted from the opposing conference room is output to the speaker 12 of the conference room A, as an echo signal e, and output via an adaptive filter 23 as an estimated echo signal e. The echo signal e output from the speaker 12 is converted into an electrical signal via the microphone 10, and then input to a subtractor 22. Also, a voice signal of a person speaking in the conference room A to audience of the opposing conference room B, i.e., near-end input signal So, is provided to the subtractor 2 2 via the microphone 10. Here, if the amplitude of the echo signal e input to the subtracter 22 via the microphone 10, which has been output from the speaker 12, is the same as that of the estimated echo signal e output via the adaptive filter 23, the echo signal e and the estimated echo signal e are offset, so that the voice of the person speaking in the conference room, i.e., pure near-end input signal So, is transmitted without an echoing phenomenon. The estimated echo signal e output from the adaptive filter 23 is expressed by the equation e = h x Y, and an audio input signal S via the microphone 3 0 is expressed by the equation S := Sr t e. Here, Y represents a far-end input signal, h represents an adaptive filter coefficient, Sg represents a near-end input signal, e represents the echo 2 signal fed back to the microphone 10, which has been output from the speaker 12. An audio signal St transmitted to the opposite conference room is expressed by the equation Sc = S-e = S0 + e-e. Here, if the amplitude of the estimated echo signal e is equal to that of the echo signal e input to the microphone 10, an echo error which is the difference between the estimated echo signal e and the echo signal e becomes zero. That is, the echo signal e is not incorporated in the audio signal St transmitted to the opposite conference room B via a transmission line, so that the audio signal St becomes equal to the near-end input signal So. During such process, an adaptive filter coefficient h is continuously updated by the equation. h(n+l) = h(n) + a x error(n) x Y, where a is a constant which is set depending on the system and usually less than 1, and h(n+l) to be updated is calculated using h(n), the constant a, the previous echo error (error(n)) and the far-end input signal Y. If the initial adaptive filter coefficient h is equal to 0, the estimated echo signal e becomes zero according to the equation e = h x Y. As a result, the audio signal transmitted to the opposite conference room B become the sum of So and e (St = So + e). That is, in the initial stage, an audio signal including the echo signal e is transmitted to the opposite conference room B. Then, after a predetermined lapse of time, i.e., when the adaptive filter coefficient is not equal to 3 zero, the audio signal St including less of the echo signal e is transmitted according to the equation St = So + e - e. Thus, in a video conferencing system adopting such an echo controlling apparatus, an adaptation process is required for a predetermined time since the initial adaptive filter coefficient is equal to zero, which is a characteristic of the echo controlling apparatus. That is, the echo controlling apparatus is operated by simply setting the initial adaptive filter coefficient to zero, without providing appropriate parameters in advance, which are required to properly set the initial adaptive filter coefficient. i Therefore, the adaptive filter coefficient is set regardless of the circumstances of a video conferencing system in the conference room, so that the preferred echo control c'annot be performed until the echo controlling apparatus has adapted. SUMMARY OF THE INVENTION To solve the above problem, it is an object of the present invention to provide an echo controlling apparatus and a control method using the same, for controlling echoing at the state when the initial adaptation has been achieved, by calculating an adaptive filter coefficient using parameters stored in advance according to the circumferences of a video conferencing system of a conference room. According to an aspect of the object, there is provided an echo controlling apparatus in a video conferencing system, comprising: a memory for storing initial parameters matching 4 - 5- the circumstance of a video conferencing system of a conference room; an echo controller for calculating an initial adaptive filter coefficient using the parameters stored in the memory, and for updating the adaptive filter coefficient using new parameters input during a conference, to remove an echo signajl; and a controller for reading the parameters stored in the memory to provide the echo controller with the read parameter, and for updating the initial parameters stored in the memory with the new parameters input to the echo controller. Preferably, the parameters include values for a far-end input signal, a near-end input signal and an estimated echo signal. According to another aspect of the object, there is provided an echo controlling method in a video conferencing system, comprising the steps of: (a) reading parameters from a memory, which match the circumstances of the video conferencing system of a conference room; (b) calculating an initial adaptive filter coefficient using the read parameters to control echoing; and (c) updating the initial adaptive filter coefficient with new parameters input during the conference to continuously control echoing. Preferably, the echo controlling method further comprises the step of storing new parameters in the memory, input during the conference after a predetermined lapse of time from the start of the conference, to update the stored parameters. 5 -5A- Accordingly, the present invention provides an echo controlling apparatus in a video conferencing system, comprising : a memory for storing initial parameters matching the circumstances of a video conferencing system installed in a conference room ; an echo controller for calculating an initial adaptive filter coefficient using the parameters stored in the memory, and for updating the adaptive filter coefficient using new parameters input during a conference, to remove an echo signal via an adaptive filter; and an adaptation controller for reading the initial parameters stored in the memory to provide the echo controller with the read out initial parameters, and for updating the initial parameters stored in the memory with new parameters input to the echo controller; wherein the initial parameters consist of values for a far-end input signal, a near-end input signal and an estimated echo signal. The present also provides an echo controlling method in a video conferencing system, comprising the steps of: a) reading parameters from a memory, which match the circumstances of the video conferencing system of a conference room ; b) calculating an initial adaptive filter coefficient using the read parameters to control echoing ; and c) updating the initial adaptive filter coefficient with new parameters input during the conference to continuously control echoing ; wherein the stored parameters consist of values for a far-end input signal, a near-end input signal and an estimated echo signal. -6- BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The above object and advantages of the present invention will become more apparent by describing in detail a preferred accompanying embodiment thereof with reference to the accompanying drawings in which: FIG. 1 is a block diagram illustrating a general video conferencing system; FIG. 2 is a block diagram illustrating an echo controller Of FIG. 1; FIG. 3 is a block diagram illustrating an echo controlling apparatus according to the present invention; and FIG. 4 is a flowchart illustrating an echo control method using the echo controlling apparatus of FIG. 3. DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 3, an echo controlling apparatus of a video conferencing system according to the present invention includes an echo controller 30, a controller 32 and a memory 34. Here, the controller 32 and the memory 34 may be implemented by a personnel computer, and the memory 34 may be a hard disk. The memory 34 stores predetermined parameters which are matched according to the circumstances of a video conferencing system of a conference room, and the controller 32 reads the parameters stored in the memory 34 and outputs the read parameters to the echo controller 3 0 such that an initial adaptive filter coefficient is calculated by the echo controller 30. Also, in order to calculate the initial adaptive filter coefficient which is the closest to the current circumstances, parameters which are fitted'to the 6 current circumstance of the conference room are output from the echo controller 30 to the memory 30, after a predetermined lapse of time from the start of the conference. Referring to FIG. 4, the operation of the echo controlling apparatus of FIG. 3 will be described. The controller 32 reads the far-end input signal Y, the near-end input signal So and the estimated echo signal e from the memory 34, which is matched for the circumstances of the video conference system, and inputs the read signals to the echo controller 30 (step 400). The echo controller 30 calculates the initial adaptive filter coefficient of the echo controller 30 using the input signals Y, So and e, and performs the echo control according to the calculated initial adaptive filter coefficient {step 410). When the video conferencing is started, the echo controller 30 calculates an adaptive filter coefficient using the echo signal e which is the far-end input signal Y transmitted from the opposite conference room, the near-end input signal So via the microphone 10 of the current conference room,'and the estimated echo signal e which is filtered by the adaptive filter 23 from the far-end input signal Y, and performs the echo control according to the real circumstance of the conference (step 420). Here, the echo control is performed by updating the adaptive filter coefficient according to the equation h(n+l) = h(n) + a x error(n) x Y, such that only the near-end input signal So is transmitted to the opposite conference room. After a predetermined lapse of time (step 430), the controller 32 stores the current signals Y, So and e transmitted from the 7 opposite conference room in the memory 3 4 in order to calculate the more approximate initial adaptive filter coefficient for the next time (step 440). Thus, the proper adaptive filter coefficient which matches for the circumstances of a video conferencing system of the conference room can be calculated, so that a conference without an echo phenomenon can be achieved from the initial stage of the conference. As described above, in the echo controlling apparatus and the method using the same according to the present invention, parameters which match the circumstances of a video conferencing system of a conference room are stored in a memory in advance, and the initial adaptive filter coefficient is calculated using the parameters to control echoing. As a result, the echo control can be effectively performed from the initial stage of the video conference. 8 -9- WE CLAIM : 1. An echo controlling apparatus in a video conferencing system, comprising a memory for storing initial parameters matching the circumstances of a video conferencing system installed in a conference room ; an echo controller for calculating an initial adaptive filter coefficient using the parameters stored in the memory, and for updating the adaptive filter coefficient using new parameters input during a conference, to remove an echo signal via an adaptive filter ; and an adaptation controller for reading the initial parameters stored in the memory to provide the echo controller with the read out initial parameters, and for updating the initial parameters stored in the memory with new parameters input to the echo controller ; wherein the initial parameters consist of values for a far-end input signal, a near-end input signal and an estimated echo signal. 2. The echo controlling apparatus as claimed in claim 1, wherein said adaptation controller reads the initial parameters from the memory when a conference is started, and updates the initial parameters when a predetermined time has elapsed from when the conference has started. 3. . An echo controlling method in a video conferencing system, comprising the steps of: a) reading parameters from a memory, which match the circumstances of the video conferencing system of a conference room ; b) calculating an initial adaptive filter coefficient using the read parameters to control echoing ; and -10- c) updating the initial adaptive filter coefficient with new parameters input during the conference to continuously control echoing; wherein the stored parameters consist of values for a far-end input signal, a near-end input signal and an estimated echo signal. 4. The echo controlling method as claimed in claim 3, also comprising the step of storing new parameters in the memory, input during the conference after a predetermined lapse of time from the start of the conference, to update the stored initial parameters. 5. The echo controlling method as claimed in claim 3, wherein said steps (a) and (b) are performed at the beginning of the of the conference. 6. An echo controlling apparatus in a video conferencing system, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 7. An echo controlling method in a video conferencing system, substantially as herein described, particularly with reference to the accompanying drawings. An echo controlling apparatus for a video conferencing system and an echo controlling method using the same. The echo controlling apparatus comprises a memory (34) for storing a far-end input signal, a near-end input signal and an estimated echo signal as initial parameters matching the circumstance of a video conferencing system of a conference room; an echo controller (30) for calculating an initial adaptive filter coefficient (30) for calculating an initial adaptive filter coefficient using the signals stored in the memory, and for updating the adaptive filter coefficient using new parameters input during a conference; and a controller (32) for reading the signals stored in the memory to provide the echo controller with the read signals.

Documents:

01972-cal-1997-abstract.pdf

01972-cal-1997-claims.pdf

01972-cal-1997-correspondfence.pdf

01972-cal-1997-description(complete).pdf

01972-cal-1997-drawings.pdf

01972-cal-1997-form-1.pdf

01972-cal-1997-form-2.pdf

01972-cal-1997-form-3.pdf

01972-cal-1997-form-5.pdf

01972-cal-1997-p.a.pdf

01972-cal-1997-priority document others.pdf

01972-cal-1997-priority document.pdf