Hi maurice , vinod and members of the group, It is regarding "acoustic" echo cancellation in hands free mobile. singal power estimation algorithm, you stated is valid for network echo cancellationl. because there you have signal in A-law or Mu-law formet. What if the signal is in raw PCM format. will this formula still hold true. Thanks and Regards, Shiv -----Original Message----- From: Vinod Prakash [mailto:] Sent: Monday, February 04, 2002 7:45 PM To: Cc: Subject: RE: [echocancel] Power measurement Hi Maurice, if I have understood right, the following needs to be done to measure the power(in dBm0) of an input signal using the power measurement device 1. pass it through the BPF specified 2. square the resulting sequence 3. pass the above , through a unity gain one pole exponential filter ,whose difference equn is, y(n) = a*y(n-1) + x(n) where a = exp(-1/(8*35)) (at 8Khz sampling rate) 4. to calculate the output power(in dBm0)the following formula is applied the output of the above filter(say y(n)) , s(n) = 3.17 + 20*log(sqrt(y(n))/8159) for the case of section 6.4.1.2.2, level measurement device for peaks the following is done, steps 1. and 2. are same as above 3. y(n) = sum(x(n)) from 1 to 280. 4. same as step of above. do let me know if the interpretation is correct. thanks and regards, Vinod. -----Original Message----- From: Maurice Givens [mailto:] Sent: Monday, February 04, 2002 9:02 AM To: Subject: Re: [echocancel] Power measurement Since I wrote this section of the recommendation, let me see if I can calrify it for you. The measurement device is a sub-paragraph of 6.4.2, Measuring input and output levels. The paragraph tells how to make the measuremen (RMS for example) and 6.4.2.1 tells how to make the measuring device for this measurement. In other words, the detector and indicator can be anything you want as long as it makes the measurement as required by 6.4.2. The indicator is your choice as to how you want to make the human interfece. The exponential filter is unity gain for a sustained signal Maurice Givens Givens Burnet, Inc. 10341 S. Prospect Ave. Chicago, IL 60643-2824 On Fri, 01 Feb 2002 06:26:37 -0000 "vinprakash366" <> writes: > Hi all, > > In the G.168(2000) standard, under section 6.4.1.2.1, level > measurement device, i am a little confused abt the > detector-indicator > block. How should this be implemented in order to decect the power > in > dBm0??. Also, is the 1-pole exponential filter mentioned in the > block > a unity gain filter?? > > thanks in advance, > Vinod > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the > author of this message will receive your answer. You need to do a > "reply all" if you want your answer to be distributed to the entire > group. > > _____________________________________ > About this discussion group: > > To Join: > > To Post: > > To Leave: > > Archives: http://www.yahoogroups.com/group/echocancel > > Other DSP-Related Groups: http://www.dsprelated.com > ">http://docs.yahoo.com/info/terms/ ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/echocancel Other DSP-Related Groups: http://www.dsprelated.com ">http://docs.yahoo.com/info/terms/ _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: To Post: To Leave: Archives: http://www.yahoogroups.com/group/echocancel Other DSP-Related Groups: http://www.dsprelated.com ">http://docs.yahoo.com/info/terms/ |