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General => General Technical Chat => Topic started by: Homer J Simpson on June 08, 2017, 11:58:08 pm

Title: Sylvania Subcarrier FM Receiver Radio
Post by: Homer J Simpson on June 08, 2017, 11:58:08 pm

https://www.youtube.com/watch?v=pbFkk9RdeQY&t=372s (https://www.youtube.com/watch?v=pbFkk9RdeQY&t=372s)

Title: Re: Sylvania Subcarrier FM Receiver Radio
Post by: rcbuck on June 09, 2017, 04:02:03 am

I built an SCA adapter for my FM Tuner back in the early 70's. There were several magazine articles published telling how to build one and how to connect it to the FM radio. If I remember correctly, you connected it to the output of the FM detector circuit. The circuit is simple, just an NE565 IC and a handful of other components.

Muzak used SCA for their "elevator music" broadcasts to businesses. I lived in Tampa, FL at the time and I could pick up 5 or 6 different SCA broadcasts. I don't know if SCA broadcasts are still in use in the same form as in the 70's. I know some of the FM stations now piggyback digital channels onto their main carrier. The digital channels usually carry the AM stations that belong to their family group of stations.

Title: Re: Sylvania Subcarrier FM Receiver Radio
Post by: BrianHG on June 09, 2017, 05:43:02 am

I know here in Montreal, they used to send modem signals on FM station subcariers, containing real-time encrypted stock market feeds.  The internet has made them obsolete.

I think something was wrong with the radio in the YT video, the quality shouldn't have been so crummy...