Posted by John Davis on December 06, 2001 at 10:47:29:

In Reply to: VLF- and longwave signals on powerlines (PLC) posted by Harald on December 06, 2001 at 06:39:46:

As Jacques noted, reception of PLCs in the 100kHz or greater frequency range is fairly common at 20km or more. In the United States, skywave fading effects have been reported on some of the more notorious PLC frequencies, implying that they are being radiated over hundreds of kilometers. There are no callsigns. Since these signals are not intended for transmission, but are supposedly(!) only conducted to receiving devices which are closely coupled to the power lines, they are classified as incidental radiators by most administrations and are not very closely regulated. In fact, in the U.S., there is a private industry group that coordinates frequencies, powers, and data modes among the electric companies, and they are supposed to advise the government periodically about the current state of affairs. Generally, no lists are made public for security reasons. But to paraphrase Galileo's purported statement: still, they radiate. Capacitive coupling between transformer windings will allow a certain amount of these signals to be conducted on lower voltage power lines at times; but as you can imagine, the lower the frequency, the less such coupling will exist. If there are transmission lines using 1000Hz control signals, you would not likely be able to receive those at your home, unless your home is located within a kilometer or two of the line. John

Follow Ups:

Post a Followup?