On Feb 16, 2005, at 10:34 AM, Steve Underwood wrote:
BTW, Steve, if you're still reading, what is the RADIO_RELAX option intended to be for in dsp.c?
It is something someone else added to the code to make the detection criteria in relaxed mode even more relaxed. If setting that helps, something in your channel must be causing some serious filtering of low frequencies. Can you try logging the audio to a file, and send it to me for analysis? chan_spy, or something like that, should do the job.
Actually, it was Florian that posted about this option. I haven't tried it (spent an awful lot of time last week compiling different configurations of stable, head, patches...taking a break this week). This is Florian said:
On Feb 15, 2005, at 1:12 PM, Florian Lefeuvre wrote:
I find the compilation option RADIO_RELAX.
this option change a threshold in DTMF detection (function dtmf_detect in dsp.c)
I remark an big improvement in the detection of the dtmf over GSM.
have you ever test this option?
RADIO is obscur for me, does it mean all wireless device?
Florian
-mark
Hi Steve,
I was the one who post a question about the RADIO_RELAX option.
In fact when I set it , I remark some better result in the detection of the DTMF...
after a few more tests, It appears I was wrong.
I did a record of samples used by the DTMF_detect function.
I obtain an audio file : PCM , 16 bits signed, big endian, Fs 8kHz.
If I compare an audio file of DTMF generated by land line with one generated
by GSM phone, I remarks a big difference.
for a land line, the shape is very good., amplitude is nearly constant for a dtmf.
for a gsm phone, the shape is bad, it can can an amplitude 5 times bigger than a land line.
After some tests, I see that lot's of errors occurs when the signal amplitude was too big (saturation).
I wonder if I should clip or attenuate the signal or a better detection...
if you want I can send you some file....
Florian .
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