The CGC Communicator Newsletter Web Posting

Regarding "Jamming" to San Diego area stations (CGC #749)

For what it's worth, point-of-purchase terminals at self-serve gasoline stations and other retail stores often produce considerable digital RF levels that interfere with AM band signals.

How far away will these terminals radiate?  It varies.  I recall hearing   digital-type background interference as far away as 300 feet from at least one such point-of-purchase merchant while tuned to KNX's relatively strong signal in the Los Angeles area in 2002.

If you get curious, next time you're "out and about," try driving around and listening to a quiet channel.  You are likely to hear a varying and  digital-sounding noise floor for quite some distances along major surface streets.

One more example of what's happening: Last week while driving in Arizona and listening to a local AM station on 1600 kHz, as I rounded the top of a hill and entered the Village of Oak Creek from the south, a digital sounding noise floor suddenly came up and produced interference across the entire AM band and "noised up" the previously clear signal of that station.

Broadcast interference will certainly grow along with digital communications growth.  I have not listened critically to FM in the same way, but wonder if the same kind of interference may be happening on that band as well.

Best,

Steve Blodgett

Phoenix, AZ

July 15, 2006

Posted by Steve Blodgett
Earthsignals.com