March 2010
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I-Buzz

Rumor has it that iBiquity is going to release a software upgrade for the AM IBOC system they peddle.  Allegedly it is going to improve the sound quality of the digital signal, allow the analog signal to increase it’s bandwidth to 10 kHz and provide data such as song titles.  No word on whether they will be providing software upgrades to consumers for the many HD radioTM receivers out there.

I have been following a discussion on AM quality over the last few days.  It seems many engineering types at least, acknowledge that analog AM can sound good, if not more natural that FM.  The addition of IBOC hybrid mode on AM station has created more noise and further degraded the station’s main signal by reducing the bandwidth to less than 5 kHz.

Tonight I am listening to WWVA on 1170 kHz, and there is this horrific white noise/hash over top of the station.  Same thing on 1190 kHz, all courstesy of WHAM 1180’s IBOC transmission.  It is one thing to trash your own station, limiting the analog audio response to 5 kHz.  It is quite another thing to trash the adjacent frequencies with noise making them unlistenable.

Here is a brief clip (recorded at 8:00 pm EDT, March 24, 2010):

Second clip, WWVA has faded out (recorded at 9:10 pm EDT, March 24, 2010)

The audio in these videos is adequate but not the best, still, it is pretty clear that there is a whole bunch of white noise on top of WWVA’s signal and on 1190 where no station is coming in. The only conclusion that I can draw is that WHAM is operating with their IBOC turned on. This was recorded at a location that is 197 miles from WHAM and 364 miles from WWVA.  I have made several better recordings directly into the computer without the video frequency readout reference.

In 1990, the FCC mandated NRSC-2 (73.44) spectral mask on all AM stations, requiring them to put in brick wall filtering to limit the bandwidth to 10 kHz or less.  They also require all AM station to do “equipment performance measurements” (73.1590) to verify that the stations are complying with FCC regulations.  This was done because of excessive sideband splatter by AM broadcasters creating interference to adjacent channel stations.  I agree in principle with the NRSC-2 standard, I think it serves a purpose.  Why then, are stations allowed to interfere with other stations with IBOC signals?  Even though Ibiquity has put up a spectral mask that complies with NRSC-2, it still creates interference.  Isn’t this a double standard?  A station in Pennsylvania gets fined $4,000.00 for operating past its sign off time (because operating after sign off might create harmful interference), yet, WHAM gets to generate noise all night and drowned out adjacent channel stations that are hundreds of miles away?

In the mean time, if the FCC inspector shows up at a station that has not made the required “equipment performance measurements” they will get a fine too.

Am I crazy, or is it hypocritical bull shit to fine one station for potential harmful interference, but then the FCC to ignores its own rules and allows another type interference?  Hint: I am not crazy.

I have recorded this in .wav format and I am sending it to the FCC with an interference complaint letter.  It is about time somebody made some noise about this noise.  Apparently, there are many engineers who feel the same way.  Will Ibiquity listen, or will they keep doing CPR on a corpse?

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2 comments to I-Buzz

  • “IBOC Interference”

    “I’ve already had situations where a local, non-IBOC station’s signal is quite listenable, but an HD Radio-equipped radio will be taken over by a co-channel (same frequency) station (video) that is running HD Radio from a hundred miles away! This will force listeners with HD Radios to lock them in analog mode, something some of the new radios are not even capable of, even if the clueless consumer would have any idea how to do it in the first place. The radio has no idea that the IBOC carriers are not in any way connected with the analog station the consumer is trying to listen to. This is a basic, fundamental flaw in the HD Radio system that will cause all kinds of grief in the future if IBOC power levels are increased, and the radios are in greater circulation.”

    http://tinyurl.com/yj888jr

    To go along with that article is this YouTube video:

    http://www.youtube.com/watch?v=g22Pq2LbJj0

    Of course, the e-skip problem for FM-HD will get worse as more stations raise their IBOC power.

    There is also this video of plain old FM-HD interference:

    http://www.youtube.com/watch?v=e0UvN767wMA

  • J. Aegerter

    Come to Milwaukee and Chicago and compare the HASH! A little peanut whistle on 640 in Zeeland, Michigan had a fairly good signal consistently in Milwaukee until WTMJ (620- 50 kW) turned on their HASH generator. The Michigan station is now completely covered up; you would not know that there was a station there. Then there is Chicago with the 50 kW “big boys”! CBS must have their heads screwed on backwards! WBBM 780 is continuous news, no music, all voice except for maybe a musical commercial. Why do they even want or need HD? The same for 670 (WSCR) which is continuous sports! These CBS radio executives must be nuts! At least WGN (720 kHz.) realized their blunder and turned off their HD. There is a rumor floating that says the reason they shut it off was that it affects the PPM data signal and renders it useless. Not sure about this, but how anybody in their right mind can endorse these HASH generators is beyond me. But then again, the United States is doing a lot of crazy things and it shows with the electorate.

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