DTMF decoder does't work correctly
Hi
(sorry for my poor english)
I use decoder DTMF HT9170d in my project. I connected my device to telephone line - it worked great when it was silence on the line. The problem occured when I was talking on the phone and tried send DTMF code at the same time- HT9170d didn't answer i mean it did not recognize any DTMF(any interrupt on STD pin). Also I connected sin generator on the line and changed frequency. If frequency was between
1,5kHz-2,1kHz decoder didn't answer, if frequency exceeded mentioned range decoder again worked properly.
What could be the problem? Thanks for any advice.