[Flexradio] [OT] Flexer discovers IBOC in back yard

[Bill Guyger]

Ken

Well now there's at least one guy that can hear the IBOC signals beside the engineering dept's of the stations in question. Actually there are a couple of receivers on the market, but like you the public in general is generally unaware that anything is happening.

Here in Dallas, we implemented IBOC, or "HD Radio" as the Ibiquity consortium (they developed the system) likes to call it in June on one of our FM's. Other stations in the market and around the country went HD about the same time because of a licensing fee discount from Ibiquity if we were on by June 30. Several stations around the country had been putting HD on the air for the last year or so, we had one on in Cincinnati a year or so ago, but manufacturers have been slow to get receivers on the market.

AM IBOC is iffy at best at the moment because of it's algorithim. I've yet to hear a AM IBOC b'cast that didn't sound like a low grade POTS Codec connection. The FCC permits AM IBOC  to be used only in the day. FM IBOC on the other hand sounds more open and has a little higher end frequency response than analog FM. Ancillary data and second program channels are also available imbedded in the data stream.

I haven't bothered with the AM side of IBOC that much, but the FM has the digital signal riding along about 30 dB down from the analog. We use only about 375 Watts TPO (Transmitter Power Output) which translated to 1Kw. ERP to get essentially the same coverage as our 100 Kw. analog which requires 30 Kw. TPO. The signal uses Orthogonal modulation techniques with 300 or so carriers at 32 or so Hz. spacing being quadriture modulated.

That's my for what it's worth for the day. Hurry out and buy a receiver.........O wait you almost can't. There's only a couple available...... though I did see that BMW is going to start putting them in their cars. Think anyone could strap a SDR 1K into their wheels???

Bill AD5OL

>>> Ken N9VV <n9vv at sbcglobal.net> 08/14/05 09:15PM >>>
Dear Flexers,
Art Bell and George Noory beware, there may be IBOC 
signals coursing through your body right now! Sounds like 
time to put on our aluminum foil undies and hats for sure!

I was totally unaware of the new Broadcast digital 
standard that is developing and being tested in the U.S. I 
was tuning around the local Chicago area AM band and 
discovered not one but two AM stations with "IBOC" 
extensions to their signals. Using the PowerSDR Console 
SPECTRUM display it was easy to see that these hidden 
signals were present. Bill KD5TFD, and a local Ham Rob 
K5UJ, quickly identified what they are.
For your viewing pleasure:
http://www.n9vv.com/1690oldies.gif 
and
http://www.n9vv.com/wbbm780am.gif 
and from Bill a link to an explanation of the new 
modulation technique:
http://www.ibiquity.com/technology/pdf/Waveforms_AM.pdf 

Do you suppose one of the talented PowerSDR programmers 
will be able to decode the IBOC signal? or perhaps it is 
proprietary?

the mystery deepens - right here in our own back yards!
de Ken
-- 
Build: 8 succeeded, 0 failed, 0 skipped

_______________________________________________
FlexRadio mailing list
FlexRadio at flex-radio.biz 
http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz