It all works fine, except of transmitting of DTMF-signals while calling from cell-phones. It takes 2-3 times to press the button to make SPA-400 "identify" DTMF-signal. When using station phohe, the situation is not reproduce, all works the right way. We performed an experiment: 1. Calling from station phone to our dial exchange, and recording (in *.wav format) call while pressing buttons from 0 to 9. 2. Open wav-file with special signal-analizing tool www.sigview.com 3. Scaling signal for number "2", for example. 4. So there is graph:
Duration = 3,255-3,239 = 0,016 sec spectrum is:
6. then we perform a call from cell-phone, recording call while pressing 0-9 buttons. 7. Open wav-file in analizing tool 8. The picture is:
Duration = 0,012 sec spectrum is:
When we compare the amplitude of the signals in both cases, it is clear we have a problem with defining DTMF because of its low value, which cause a distortion.
The "2" is 697Hz and 1336Hz respectively. We have 687Hz and 1343Hz for stationary phone, and 687 and 1312 for cell Nokia.
The "line busy" signal:
We tryed to change "DTFM power" parameter many times from -400 to 20, and other regional settings, no right result. What shell we tune to make it transmitt DTMF-signals (in case of cell-phone) with the first attempt?
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