[BC] dtmf tone filter solutions

[DHultsman5 at aol.com]

I would like to see more information regarding CBS Radio being sued over 
their semi-audible "Net Alert"  tones.  I believe they were the first Network to 
use tones on the network line.

As I recall it had 9  codes.  It could be used to begin commercials or end of 
commercials.  It had and emergency which gave you notice up an upcoming 
bulletin.

The device we had was a tube type unit. and was labeled Net Alert.  They used 
a combineation of two tones very short like "bleeps"  bareley audible.

We had a test tape for working on the decoder which consisted of tube type 
multi-vibrator decoder circuits and a back lit digital readout from 0 to 9.

It was ceratinly less notable than many of the other tones later used by the 
other networks.

Dave Hultsman
>From NAB Austin

> In fact, when I was in Radio, CBS was sued because they used some 
> audible high-frequency squitter to signal over the network. Since it 
> was within the normal program audio band, the FCC disallowed its use 
> and CBS had to replace their queuing boxes with ones that used 
> sub-audible tones.
>