> Digital power is 1/10 of the analog ERP...but with the
> signal recovery and error correction of the digital signal
> (plus the redundancy of the signal since it is both above
> and below the analog signal) the digital rcvrs actually have
> a better chance of decoding...In fact, land mobile folks
> have noticed the same thing with digital (P25) radios in
> place of analog FM...the coverage tends to be MORE than the
> analog...especially in areas where the analog would get
> noisy, the digital is still 100% copiable...and clean (due
> to it being digital!!)
>
>
KIOL is proof that the digital signal would not decrease the coverage area of an FM station by initial "guesstimates" as high as 40% as the digital would simply vanish at ~ 3.14mV/m (50dbu) where analog with static and fading can be good on the open road {I-45 Houston-Dallas} to 0.05mV/m (34dbu). Good news for digital signals, but now I wonder if the FCC will have to come up with a new more restrictive Table of Separation for stations in the digital mode. Shows that Ibiquity is still "flying by the seat of their pants" when it comes to the capability of FM HD Radio. I do believe the the Ibiquity system shows a good deal of promise. Is there superior FM Digital service in operation? Glad to see Houston getting on-line with FM-HD at long last, now to see if there will be a big demand for receivers.
>
> > This is why I hope that someone comes up with a good digital
> > system for AM radio also that will work 24/7 and can be used
> > in cities like Houston that have stations that are only
> > 20kHz apart. Ibiquity's system can not be used on half of
> > the stations in Houston on AM because of the interference
> > they would cause other stations and why Ibiquity's digital
> > can not be used at night. I read an artical that two
> > Beaumont stations are using Leonard Kahn's Cam D digital on
> > AM with good results, but I believe a totally different
> > system than Ibiquity's. KRCM 1380, which is suppose to move
> > to Shenandoah and KOLE 1340 Port Arthur. Have to admit I
> > don't know much about it, there is an article about Cam D at
>
> Cam-D uses the same practice as Kahn's POWERSIDE
> system...which was made from the ISB (Independant SideBand)
> Stereo system of KAHN...In the POWERSIDE, one sideband is
> fed a higher level of L+R than the other....and in some
> cases, it would actually put NO audio in one sideband...thus
> making the signal a SSBWC or SingleSideband With Carrier
> signal...which is compatible with analog envelope AM
> detectors common in AM mono rcvrs..The CAM-D evidently puts
> the digital information in the unused sideband...but if this
> is a fully digital signal or a hybrid with the analog
> providing part of the audio and the digital providing the
> L-R and additional high end is not known since Kahn does not
> provide technical information...(Leonard is a brilliant
> engineer but a total A$$ when it comes to marketing and he
> refuses to let anyone else market or license his
> ideas...this is why HIS ISB stereo system died!...noone
> could get his license to produce REAL decoders for his AMS
> system...the SONY multi decoder chip was a best guess and
> was not 100% tweaked for his format...according to Kahn!)
>
>
> >
> >
http://beradio.com/iboc_update/iboc_update_020905/ will
> > have to see what happens if this system really works on AM
> > with adjacent stations. It could change the whole picture
> > of what happens to digital on AM radio.
>
> At TAB, Ralph McBride (owner of 1340/1380) got laughed at by
> several engineers, etc during a "discussion" of CAM-D vs
> IBOC...He is not a radio person...much less an
> engineer...and hearing 1380 blow splatter up and down the
> band proves that (it and 1340's audio changes from day to
> day on being good or being clipped heavily and sometimes
> distorted..) CAM-D is going to die a quick death because
> KAHN waited too damn long and will not post any real
> technical data..even his last letter to the FCC was a
> joke...it had NOTHING in there about how WELL his system
> works (or how it works period!)...all he did was bash
> IBOC..and that wont help him win his point..
>
Kahn is a strange bird that could come up with a workable AM digital system for the US, but as you stated will give no information and you are correct his last comments to the FCC blasting IBOC served no positive purpose. The fact that you hear splatter up and down the dial does not sound like it would be a replacement for Ibiquity's AM digital, which does the same thing. I have not kept up on HD radio, will have to check out specs on DRM AM HD, since it is used in Europe where very tight spacing and high power is used, it may be the answer for AM digital. Unless Ibiquity can come up with a HD signal that stays with-in a +/- tolerance of a stations nominal frequency, example 1380: L (1375-1379kHz) R (1381-1385kHz) carrier on 1380, I don't see the Ibiquity HD AM radio working on many stations in the urban regions of the country and never at night. The NE US, So Cal, S Fla and the major cities like Houston, Dallas, Chicago, etc. where 20kHz between stations that are listenable is very common or even 1st adjacent like KRCM 1380, KULP 1390 and KHCH 1400. All receivable and listenable in the Galleria area daytime.
>
> > It would also be a real plus if what ever system the U> uses
> > on AM is totally different and incompatible with Mexico or
> > any point south. That will eliminate the interferenc from
> > Mexico and points south and really clean up the AM band in
> > the SW at night. I'm sure Mexico would be all for it also,
> > as many US stations send all their power into Mexico at
> > night causing tremendous interference problems for Mexican
> > stations that hane come on the air.
>
> No, it wont help...any other digital format out there will
> still cause interference....even hear a digital signal when
> an analog carrier is present? it is gone! Same thing happens
> when there is a digital vs digital issue...the decoder will
> not be able to lock in and decode properly...If the format
> is the same, it MAY lock up on one or the other...switching
> between one or the other...
> With different formats, it would not lock up at all if the
> signals are equal in level...
>
This is my ignorance of HD Radio at work, we are using analog and digital on the same frequency now with no problem. If the digital systems were totally different and receivers sold in the US were sold for the US standard used for digital radio, wouldn't the other digital signals be rejected or undetected being a different system?
Side note, the elimination of Channels 2 through 6 would be a plus, especially if Channels 5 and 6 were turned over to FM for LPFM/TIS {66-72mHz} and NCE {76-88mHz) and stop the issue of translator licenses, with the exception of rural areas that fall into the white or gray area of coverage. The translator station craze has gotten out of hand and out of the scope that was originally intended by the FCC. The FCC may have to reclaim Channels 52 through 56 though for TV.
Channel 5 would work well with low power stations of a max of 1kW @ 100m and Channel 6 would be okay at todays power/separation regs. This would give LPFM a home and FM would suit TIS stations better than AM, although with the exception of huge airports like IAH, TIS power level would be 100 watts at 30 meters. Airports like IAH could operate up to the full 1kw @ 100 meters. This would also give the NCE portion of the band which is over crowded and leaving many Colleges/Universities that would like a station with no open frequency in urban areas a home. I was trying to come up with a Class A signal for Texas City in the NCE band with no avail.
Thanks for the info CW.
Mike O
