Monday, June 22, 2009

DTV Transition - Boon for Scanners?

Has anyone else noticed a marked improvement in scanning the federal bands since the turn-off of analog full power TV stations? In the last couple of weeks, I have traveled to New York City, Los Angeles and Tucson, AZ and noticed that both my Uniden radios and GRE/Radio Shack scanners are not getting clobbered by interference and images in the 162-174 MHz band like they used to.

Normally all of my newer P-25 capable scanner would exhibit lots of signal level on their S-meters while scanning through the VHF bands, even when no signal was being received. I've always believed that this was a result of the front end of the radio being overloaded from high levels of RF. But I also believe that the problem was a result of the scanners receiver design and not the TV stations. Problems from this overload included low sensitivity and images of the wide-band FM audio sub carrier on some VHF frequencies. These have all seemed to vanished since the analog transmitters have shut down. Even at my home listening post, where I have a direct, line-of-site view to all the TV stations in the Portland, OR area, things are very quiet across the VHF federal and UHF military air bands.

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