The Southern Ontario/WNY Radio-TV Forum / What Could Cause This Issue On An FM Station?

**Posted by RadioActive** May 25, 2025 8:49 am

I was going to post this last week, but completely forgot - and now the problem seems to have resolved itself.

I'm referring to CHIN's FM station at 91.9 in Toronto, where for at least a week, the sound was only coming out on one channel. I'm not a regular listener, but was tuning through the band when I stopped because what I heard so unusual. While on headphones, the sound was only on the right side. The left was completely silent. It sounded very odd.

I went back a few times over the next few days to see if it was still happening and sure enough, it was. If you were listening in mono, it was normal. But as soon as you switched to a stereo signal, in your car or on headphones, half of it was gone.

I listened on Sunday and it appears to been fixed. But what could cause something like that and how could it go on for so long? I'm not sure I've ever heard that happen before.

**Posted by Forward Power** May 25, 2025 9:00 am

There's a chance that the left channel had dropped out/been somehow disconnected somewhere in the audio chain, perhaps going into the on-air processor (e.g. Optimod, Omnia) or anywhere after the main program output of the on-air console. A lot of it depends on how CHIN feeds the 91.9 transmitter and where the processor is; if they're feeding the transmitter via an IP connection or by old-fashioned 15 kHz telco lines, the processor would need to be at the transmitter site so that the composite signal and an RDS signal, if applicable, can go into the transmitter - most FM transmitters are fed via the composite input on a BNC connector. At the studio end, from the on-air console, there would be, at the very least, the AlertReady decoder (Sage Digital ENDEC unit) and the studio side of the feed to the transmitter.

Apologies for the tech jargon... I often worked with this kind of stuff in my previous years in radio.

**Posted by RadioActive** May 25, 2025 9:06 am

I also wonder why it took them so long to fix it.