I am using a GE865 to receive modem-like tones from far-end signalling equipment over the PSTN. The audio is received over DVI. All works fine except that in some instances if the far end equipment is transmitting max signal levels (though still within PSTN standards) the received audio is badly distorted – the recevied signal is clearly saturated with unwanted components. Clearly some element in the recieve audio front end is being over driven.
The situation can be remedied by using PSET with -6 as scal_out. But when a call is made we don’t know which kind of equipment we are talking to, so the -6 attentuation can hurt us for some equipment because the signal is now a little bit low. Ideally we need AGC.
I notice there is an AGC section in the PSET command as well. Does this apply to the digital audio receive path? How is it used? Are there any examples?
Do SHFAGC and SHSAGC only apply to the analog front end?
The AGC is part of the echo canceller system and works only on hte microphone path.
I believe if -6dB solve the issue for high level tones and at the same time it lowers a bit hte other case why don’t try -3db?
Thanks again for your reply Luca.
Yes, indeed I have been experimenting with -3 and it looks like that might be the solution.
all the best,
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