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Re: [IRCA] All-Digital AM Co-Channel Lab Test Results Unveiled
I totally agree with Rick as I monitored both KRKO and KKXA and both caused a lot more sideband hash in full HD, even at this distance. I can detect KRKO's hybrid hash nightly on 1370 KAST, a local at 5.3 miles. It is not an issue, but it sure can be noticed in the background. In total HD, the hash was noticeably noisier. I am sure for local listeners a few miles farther from KAST, the noise would have had them tune out of KAST. I just do not see IBOC working on AM in any regard. If the dial was go all HD, then most distant reception would be history, let alone DX.
Patrick Martin
Seaside OR
KGED QSL Manager
> From: ricklew@xxxxxxxxxxxxxx
> To: irca@xxxxxxxxxxxxxxxx
> Date: Fri, 22 Apr 2016 15:24:40 -0700
> Subject: Re: [IRCA] All-Digital AM Co-Channel Lab Test Results Unveiled
>
> Russ,
> At least in the Seattle area all-HD tests, the interference was much
> greater.
> One would expect the opposite, since the hash would be in the center of the
> main frequency, but the hash was maybe two or three times more intense than
> in the hybrid mode.
> Thus, 1360 in Tacoma was mixed with noticeable HD hash during the KRKO
> tests, although none is heard normally.
> The area's 1400 is a much weaker station, and it stood no chance against the
> HD onslaught.
> Incidentally, I'm not local to KRKO. It's a strong signal which can be heard
> in HD during the day, but not a full-quieting local.
> Same for 1520, which is in Snohomish County (I'm in King County.)
> Based on the tests I've heard, the hash from a completely local HD station
> would be so noisy in analog that it could persuade analog AM listeners to
> turn it off rather than even look around for other stations on the dial.
> If the AM band were a mix of HD-only and analog signals, it would be almost
> like having a bunch of vacuum cleaners running, each taking up a total of
> 60kHz.
> I think that's the most graphic way I can explain what it sounded like in
> analog.
> But even in an all-HD situation, power would likely need to drop
> considerably to keep HD-only stations from interfering with each other.
> I can't see how all-HD signals would work compatibly in either a mixed or
> total HD mode.
> It was that bad.
> --
> Rick
>
> -----Original Message-----
> From: IRCA [mailto:irca-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Russ Edmunds
> Sent: Friday, April 22, 2016 1:51 PM
> To: Mailing list for the International Radio Club of America
> <irca@xxxxxxxxxxxxxxxx>
> Subject: Re: [IRCA] All-Digital AM Co-Channel Lab Test Results Unveiled
>
> Bottom line, this is, after all, the NAB, and their mantra is "More, more
> more stations". I would expect their rsults to understate the potential
> issues.
>
> That said, a straight up digital signal would occupy the center of the main
> channel - where today's analog signal is. And the digital signal should
> occupy less bandwidth by itself and a typical analog signal. The IBOC hybrid
> mode has the analog signal at center and the two hybrid digital signals on
> either side. Thus the combined IBOC signal occupies substantially more
> bandwidth than a single digital signal. That's why Chuck said ( or one
> reason why ) it wasn't comparable. But that also doesn't predict much else.
>
> Russ Edmunds
> 15 mi NW Phila
> Grid FN20id
> <wb2bjh@xxxxxxxxx>
>
> AM: Modified Sony ICF2010's (2) barefoot w/whip
> FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder; Onkyo T-450RDS; Tecsun
> PL-310 ( 2); modified Sony ICF2010 w/APS9B @ 15'; Grundig G8 w/whip;
> modified Sony ICF2010 w/whip
>
>
> On Fri, Apr 22, 2016 at 12:15 PM, Nick Hall-Patch <nhp@xxxxxxxx> wrote:
>
> > It's quite easy to correlate Chuck. Just add ignorance and stir. I
> > don't believe they actually said anything much about the digital
> > signal, so assumption of all digital IBOC can reasonably be added to
> > that mix. (other details about demodulation of the analog signal are
> > also missing)
> >
> > Audio examples would be nice, and might help to convince the doubters..
> >
> >
> > http://www.radiomagonline.com/deep-dig/0005/broadcast-engineering-conf
> > erence-radio-technology-forum-sessions/37600
> > offers descriptions of the conference sessions, but I haven't been
> > able to quickly track down any more detailed results than what Dennis
> linked to.
> >
> > http://diymedia.net/old/stuff/AM_IBOC_Test.pdf has a nice graphic on
> > the first page which I assume is what Chuck is alluding to in terms of the
> > difference between present IBOC and all-digital IBOC. Is that the case
> > Chuck? If so, perhaps you could suggest a listening test that could
> > be done with today's systems (thereby saving me the trouble of doing it
> > incorrectly)? Those secondary OFDM subcarriers already sound pretty
> nasty
> > on KRKO's signal this morning, and they would be stronger in the
> > digital only version.
> >
> > best wishes,
> >
> > Nick
> >
> >
> >
> >
> >
> >
> > At 05:03 22-04-16, you wrote:
> >
> >> ...
> >>
> >> I don't see how you can correlate hybrid IBOC to all digital IBOC.
> >> What you hear with KRKO/KAST is different from what you will hear
> >> with all digital as the power spectrum and subcarrier levels are
> >> vastly different.
> >>
> >> Chuck
> >> ________________________________________
> >> From: IRCA <irca-bounces@xxxxxxxxxxxxxxxx> on behalf of Nick
> >> Hall-Patch < nhp@xxxxxxxx>
> >> Sent: Friday, April 22, 2016 4:51 AM
> >> To: Mailing list for the International Radio Club of America
> >> Subject: Re: [IRCA] All-Digital AM Co-Channel Lab Test Results
> >> Unveiled
> >>
> >> I presume "D/U" abbreviation in this piece refers to "desired /
> >> undesired"?
> >>
> >> I wonder if someone recorded audio from those tests, rather than just
> >> tossing dB's around? I have a recording of KAST-1370 from this
> >> morning that says otherwise, with KRKO-1380 IBOC sidebands about 25dB
> >> down and....welll, KAST is readable, but I wouldn't say it's lacking
> >> interference. The noise becomes really dominant if KAST is less
> >> than ~15dB above the IBOC level.
> >>
> >> best wishes,
> >>
> >> Nick
> >>
> >>
> >>
> >>
> >> At 21:05 21-04-16, you wrote:
> >> >http://www.radioworld.com/article/all-digital-am-co-channel-lab-tes
> >> t-results-unveiled/278670
> >> >
> >> >Sent from my iPad
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