I am using MT8880 and 89c51 in my project. I can send DTMF out. however i found that the chip can't 100% receive the correct DTMF signal. just 5% chance to get the correct tone.
any idea and comment? thank you for your help in advance. Regards,
Raymond
You can use a scope to check the input signal for:
- clipping (signal too loud)
You can sample it with your PC soundcard and "CoolEdit" and then do an FFT to check for:
- (reverse-)twist (one frequency louder than other frequency)
- frequency accuracy (tones too high/low)
- noise (tones don't stand out clearly enough)
Marc
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