The story at the link below is about a Japanese radio station ending the practice of using electrical power lines to send its AM signal out - instead of a traditional transmitter. Even though the article talks about ending the practice at this particular outlet, two others still exist.
Obviously this must have worked, but I can't quite figure out how. Wouldn't the amount of electrical interference this would generate completely destroy any chance of reception? Is this something done elsewhere? Have to say I've never heard of this before. Could this really work?
It's called carrier current radio, and was very much in vogue for campus radio stations in the 1960s and later. A relatively low power AM transmitter has its output capactively coupled into the power line, and the power line wires radiate the signals. The transmission distance would be limited among other factors by the distance to the next power step-down transformer, as the transformer core and windings would act as a choke. Radio Glendon at York University was one of a handful of Canadian carrier current stations, operating 10 watts at 800 kHz. ISED's Broadcasting Procedures and Rules, Part 2, still contain a provision for licensing carrier current stations. Wikipedia has a list of current and former stations: https://en.wikipedia.org/wiki/Carrier_current The dominant company supplying transmitters was LPB (Lower Power Broadcast), now defunct. It had a complete range of transmitters and coupling accessories. You can see a detailed explanation at https://www.steampoweredradio.com/pdf/lpb/lpb%202-20%20am%20carrier%20current%20system.pdf
Yes, thanks for the explanation Skywave. I had no idea this was possible. Although on AM, I can't believe the signal would be all that listenable. Still, I guess some signal is better than no signal at all.
When I first attended McMaster in 1972 I was excited to listen to CFMU which at that time operated at 650. I wondered if WSM would overpower at night. All I received on my 1965 transistor radio was static. Then a fellow student advised me that the station operated via carrier current and could only be heard in the various campus residences. Beginning in January 1978 CFMU began OTA operation on 93.3.
