by jon » Mon May 18, 2015 3:40 pm
As a teenager in Vancouver, I hated SCMO. At that time, CKLG-FM provided the SCMO for Muzak. And CHQM-FM provided the SCMO for their own Q Music.
My Father bought an EICO FM Tuner kit in 1961 in Bellingham, shortly after CHQM-FM signed on. He did not buy the Multiplex unit, which was an expensive add-on. Both QM and LG had significant white noise on that receiver. LG-FM could be really bad because they did not run the audio compression that CHQM-FM did, so quiet passages of music got hit pretty badly. It only got worse when Tim Burge (and possibly others) cut back on the levels for spoken content, in reaction to listener complaints about the announcer's voice and commercials being so much louder than the music.
I should clarify: CHQM ran different audio compression specs on AM and FM. When I worked there in 1971 and 1972, you could easily see it as they had modulation percentage meters, which looked somewhat like VU meters, in the racks in or near the transmitter remote controls. The FM "attack" when a piece of music got suddenly quiet was fairly slow, and you could watch the meter as the compressor gradually raised the level. AM was pretty much sub-second response. Lest you think I should have been doing my job rather than watching the meter, I should mention that the FM meter was in the same racks as the automation machine (the ancient IGM Serial Number 0000005), which was right beside the AM transmitter remote controls and monitoring.
A couple of interesting points have come up since I originally posted this. One post I read says that a Toronto ethnic station on SCMO has always been careful to contract with a Mono FM station for SCMO because they claim it gives them a cleaner signal on the SCMO side, because there is no Stereo Multiplexer 19KHz "tone" being transmitted. Another post pointed me to a bunch of different no-name SCMO-capable portable radios that also receive standard AM and FM. That poster has seen them for $2 used at Goodwill, but the ones on eBay are $20-$35 U.S., though I think the cheapest one was just a circuit board. It might be interesting to see just what is being carried on SCMO these days. I haven't seen an SCMO license being granted or renewal on the CRTC site in a very long time, but that could be more to do with the new Admin Renewal "quick stream" that the CRTC uses now.