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AM-IBOC Interference

K

Ken Gustafson

I just read an old thread here about AM-IBOC interference to KDKA-1020 and other stations from WBZ-1030. This caused me to harken back (AM history is my thing so I do that a lot) to something I read in the 1960s. There was an experiment (or proposal) to reduce interference between these two stations by using single side band. KDKA used the lower sideband, WBZ the upper. A company called Kahn Labs did the engineering, I recall. Anyone know about this? Would it be a partial fix for the mess that is the AM band if all stations were single side band?
 
After the whole AM Stereo thing started fading away (much of which, due to Leonard's lawsuits), Leonard Kahn was marketing his AM-ISB stereo exciters as "Kahn Powerside". Essentially the stations (not very many) who had an adjacent station at night would run modulation on center/upper or center/lower sideband. KOA in Denver was one of the original (claimed by Leonard) success stories,.

One of the problems with the Powerside (among others) was when digital tuners came out, there was no way to tune to a sideband, as with a capacitor-tuned radio would. There was some debate with the FCC, whether Leonard was just trying to circumvent the type accepted AM stereo method of CQUAM, by calling it something else.
 
An idea that looked good on paper but didn't live up to the hype when actually put to the test....
Not unlike the Kahn-Hazeltine AM stereo plan....one station in NH that I know of (what was then WKBR - now WGAM 1250) experimented with this for a couple of months -- and abandoned it (and AM stereo) altogether.
AFAIK.....the only receivers/tuners in the marketplace for the K/H format were prototypes....I never saw or heard of one for sale anywhere....
Ditto Harris, Philips, Magnavox, etc.
 
Sony had at least two models that received all five systems, with a switch between Kahn and the other four. Portland had a Kahn station, KKSN.
 
MarioMania said:
Is WBZ's HD Turned off now iHeart is owning it?
Click to expand...

99% of the reason AM stations have stopped doing HD/IBOC is due to the transmitter exciter has died. The original AM HD exciters were basically a PC, including spinning hard drive. Since the manufacturers stopped supporting these exciters, most stations just dropped it when their exciters bit the dust.
 
I think I'm correct that when I listen to WZKY, which made a point of mentioning it was in stereo, some songs use both speakers. I can hear some instruments from one speaker and voices from the other. So they must still be doing it.
 
Kelly A said:
Which is too bad. Where I live in Virginia south of DC, I used to enjoy listening to WBZ skywave in HD at night. I even have a WBZ preset on my radio.
I'll have to E-mail their engineer and inquire why the change.
Click to expand...

For a long time, their night time HD was interfering with Bob Savage's radio station in Rochester NY.
 
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