[BC] dtmf tone filter solutions

[RichardBJohnson at comcast.net]

Correct. Even if the program channel cut off at 300 Hz,
it is not a brick wall. It would be 20 to 30 dB/decade so
a frequency below 50 Hz, say 30 Hz would only
be 20-30 dB down and the CBS box with the
relay-controlled numbers WACE had in its main
studio was able to detect it. WACE was a
"CBS Flagship" station when I was CE.

There was nothing audible on-the-air, and at
the time, audible signals were not allowed on
program channels. Also CBS used a "Program
Channel D" which was, if I recall correctly,
100 Hz to 5 kHz.

--
Cheers,
Richard B. Johnson
Read about my book
http://www.LymanSchool.org


 -------------- Original message ----------------------
From: Tom <Radiofreetom at gmail.com>
> 20 Hz.
> 
> RichardBJohnson at comcast.net wrote:
> > ...and the 110 volt ringing frequency is?
> >   
> -- 
> Tom Spencer
> PG-18-25453 (nee' P1-18-48841)
> http://radioxtz.com/
> Part 15 transmitters on AM 640 and FM 100.1