On the new cordless HD Radio….


In response to "Finally: portable HD Radios coming in days

I stand amazed! Wow, just saw on RBR today the latest line of Hi-Deaf cordless radios including the newest radio’s friend helping us build key TSL-the IPOD player, all for the low price of 150.00 suggested retail price. We had listener complaints the whole weekend in Jacksonville, FL from 105.7 FM licensed to Baldwin, FL with 25KW ERP directional. Our CBS neighbor licensed to Deland, FL on 105.9, but serving the whole of Orlando with the live Oldies format has tremendous digital carriers that drift up here during those nasty FM (VHF) tunneling inversions that started last Thursday due to a low pressure cell off shore. It’s so regular now that I don’t have to check the power output any longer when the interference calls come rolling in. So I just say "tune to 105.9 and if you hear oldies the problem is digital noise" at the edge of the 1-2mv/m signal area from the FM neighbor above us.

It’s just one more knife in the analog side of broadcasting that eliminates signal coverage outside of the 5mv/m or better than city grade signal level during these VHF weather-related inversions. "We’ve always had that problem since the creation of FM." Sounds good and true. But one thing ain’t true. We never had it hitting us from the co-channel AND both adjacent channels at the same time AND with the peak equivalent power of 100 times our own RF output (transmitted power level in the listener’s radio).

You see folks this is not just modulation noise that rises and falls with audio peaks. These are hardcore multiple bursts of carriers when added together in real energy levels play havoc with tuned circuits of today’s auto radio receivers. So we’re not talking about a bit of noise. We’re talking about separate carriers (RF generators) that exist off each side of the conventional transmitted FM and AM signals with the approval of NAB and the key owners of radio stations who benefit from cutting the signal from adjacent channels down to about half the old school signal levels. Rock on!

–Jerry Smith, consulting engineer