eblueman
Newbie level 1
How to Filtering DTMF Tones?
Dear Friends,
I'm trying to build an micro controller based system to work as an phone auto dialer. this dialer must dial a calling card number before users number.
in an example mind that you have a calling card with number cccccccc and pin pppp when you try to dial xxxxxxxxxx and when you pick up the phone, before you start to dialing this device must dial cccccccc and then pppp and then your number xxxxxxxxxx
the most important leakage in available circuits and devices is speed, and this make messed up dialing tones as like as [ccccccxcxcxxxxxxxxpppp].
in this case we must ask user to wait enough for device dialing process OR design a circuit to buffer user's dialed number.
for buffering we must use a encoder chip but first we must disconnect his/her direct DTMF access to out-side via phone line.we must have a FILTER to block DTMF tones
Please help me if you have any idea for this DTMF FILTER or described problem.
Dear Friends,
I'm trying to build an micro controller based system to work as an phone auto dialer. this dialer must dial a calling card number before users number.
in an example mind that you have a calling card with number cccccccc and pin pppp when you try to dial xxxxxxxxxx and when you pick up the phone, before you start to dialing this device must dial cccccccc and then pppp and then your number xxxxxxxxxx
the most important leakage in available circuits and devices is speed, and this make messed up dialing tones as like as [ccccccxcxcxxxxxxxxpppp].
in this case we must ask user to wait enough for device dialing process OR design a circuit to buffer user's dialed number.
for buffering we must use a encoder chip but first we must disconnect his/her direct DTMF access to out-side via phone line.we must have a FILTER to block DTMF tones
Please help me if you have any idea for this DTMF FILTER or described problem.
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