Hi all, I'm in trouble with a DTMF encoder that I'm trying to use
in a new proyect, the HT9200A from HOLTEK, it's a serial (2 wire) DTMF
encoder very easy to use, only 3 wires needed (CE , SDATA, SCLK), the
logic is working fine and the tone is generated but at the begining and
the end of each tone I heard a very short sound "TAC" , in the scope
I can see that I have a DC jump at the begining and at the end of the tone
and I have no idea how to avoid that DC jump!.
using coupling capacitors I found no difference, the ugly sound persist :(
the only way that I could avoid that sound is change the tone without
stop it, but most dtmf decoders needs at least 30 ms of silence to detect
a new tone, so I think that is not the solution.
anyone have an idea about how to avoid this DC jump sound?.
thanks in advance.
   Leandro J. Laporta (LU2AOQ)
   mail: lu2aoq@yahoo.com
   wrk: Arg. Assoc. for Space Technology.
   ham: TCP/IP high speed group HSG