Re: [IRCA] IBOC Hash AM vs FM OT question

["Paul B. Walker, Jr." <walkerbroadcasting@xxxxxxxxx>]

I have to ask a stupid question.. you say you get the analog station, but
the RDS from the HD station.. do you know for sure you've locked into the
HD signal of a station?

Because some analog stations have RDS and it has nothing to do with HD.. I
worked for a station that had RDS and was not operating in HD.

Keep in mind, I know very little about HD radio and how radios display
things on the actual display on the front of the radio.

Paul


> > From: mwdxer@xxxxxxxxx
> > To: irca@xxxxxxxxxxxxxxxx
> > Date: Wed, 20 May 2015 01:08:16 -0700
> > Subject: Re: [IRCA] IBOC Hash AM vs FM OT question
> >
> > Mike,
> >
> > I have about 200-300 FM QSL's from the 70s and 80s. I have 66 TV QSL's
> too. The FM dial is so much different now with the number of LPFM's,
> translators, HD. etc.  It is like a different World. Almost like I am a
> beginner. Except for the occasional tuning around on the van radio, I have
> really been out of touch on FM. So many of the weak translators I get are
> barely above the noise floor and some change places. That never used to be
> the case back in the old days. Except for skip, the same stations were
> always there. This weird switch-a-roo between an an analog FM coming in,
> over to another station in HD, is strange. Sometimes I will have the analog
> station, but the RDS from the HD station.  I have already heard several
> scatters, a man in FF on 88.3 briefly the other day.
> >
> > 73,
> >
> > Patrick
> >
> > Patrick Martin
> > Seaside OR
> > KGED QSL Manager
> >
> > > Date: Tue, 19 May 2015 23:59:02 -0700
> > > From: michael.d.hawkins@xxxxxxxxx
> > > To: irca@xxxxxxxxxxxxxxxx
> > > Subject: Re: [IRCA] IBOC Hash AM vs FM OT question
> > >
> > > Patrick,
> > >
> > > You do realize you're going to need to buy out a stationery store to
> get
> > > enough supplies for your FM QSLs if you get serious about FM.  I do
> poorly
> > > with skip here and I still have about 300 Es receptions.  If you get
> real
> > > patient, you can also use meteors.
> > >
> > > Mike Hawkins
> > >
> > > On Tue, May 19, 2015 at 9:21 PM, Patrick Martin <mwdxer@xxxxxxxxx>
> wrote:
> > >
> > > > Thanks Scott. I kind of follow it. 88.1 is interesting here, as when
> I
> > > > first tune to it on the Sony, I get analog KWAO Ocean Park WA, but
> within
> > > > seconds, HD signal KQOC Gleneden Beach OR takes over the frequency
> and
> > > > locks the HD, totally eliminating analog KWAO. Infact on any
> portable on
> > > > non HD radio, all I get is KWAO. I was quite taken back when the
> Sony gave
> > > > me KQOC!  The same is true with 96.5. When I first tune it in, I am
> getting
> > > > analog KCYS Seaside, with within seconds again (depending of the
> signal),
> > > > KJAQ Seattle locks the frequency. At that point hearing KCYS takes
> work and
> > > > I have to turn the yagi to knock KJAQ down  to get local KCYS. It is
> odd
> > > > sounding to me.  Also sometimes when I land on 96.5, I immediately
> get the
> > > > KJAQ ID, before I get the station! So the audio is KCYS (also
> Country) and
> > > > I am getting the ID RDS from KJAQ.  I guess that is what you have
> > > > explained, but it is different to say the least! So the sub channels
> I am
> > > > hearing, when they pop in at 1% of th
> > > >  e analog signal. I thought I might get some HD from Seattle as I
> know
> > > > that years ago when the powers were a lot less (60s/70s), some ran a
> couple
> > > > KW or so from Cougar Mt and I got them in full FM Stereo. One I
> wanted was
> > > > KNHC 89.5, but so far no luck. even in analog. I used to get it
> years ago
> > > > off and on, but I did have a better yagi. I may stack two FM6's.
> I'll say
> > > > one thing, HD FM is a different thing. It will be interesting with E
> Skip.
> > > > I guess I could get the RDS ID without getting the audio from the
> station
> > > > too, depending on how stable the signal is. Being away from FM DX
> for 25
> > > > years, the dial is sure a lot different than it was.
> > > >
> > > > Patrick
> > > >
> > > > Patrick Martin
> > > > Seaside OR
> > > > KGED QSL Manager
> > > >
> > > > > Date: Tue, 19 May 2015 14:19:15 -0400
> > > > > From: scott@xxxxxxxxxx
> > > > > To: irca@xxxxxxxxxxxxxxxx
> > > > > Subject: Re: [IRCA] IBOC Hash AM vs FM OT question
> > > > >
> > > > > For those who are interested in the technical reasons why Patrick
> > > > > doesn't get the same kind of adjacent-channel hash that those of
> us in
> > > > > urban areas do, read on. For those who don't...another thread will
> be
> > > > > along shortly with convention news ;)
> > > > >
> > > > > --
> > > > >
> > > > > As far as propagation is concerned, there is nothing at all magical
> > > > > about the digital signals that flank the analog FM signal to
> create HD
> > > > > radio on FM. The ionosphere doesn't care whether it's analog or
> digital
> > > > > modulation. If a signal is (a) strong enough to be received and (b)
> > > > > doesn't have something stronger sitting over it, you'll get it. If
> > > > > either of those factors doesn't exist, you won't.
> > > > >
> > > > > So: it helps to think of the digital signal as something separate
> from
> > > > > the analog. If you're getting KUOW in HD, for instance, you're
> really
> > > > > getting:
> > > > >
> > > > > --94.6 ---
> > > > >
> > > > > KUOW lower digital carriers (on the same piece of spectrum used by
> an
> > > > > analog 94.7 signal)
> > > > >
> > > > > --94.8 ---
> > > > >
> > > > > KUOW analog signal (centered at 94.9)
> > > > >
> > > > > --95.0 ---
> > > > >
> > > > > KUOW upper digital carriers (on the same spectrum used by an
> analog 95.1
> > > > > signal)
> > > > >
> > > > > --95.2 ---
> > > > >
> > > > > Depending on the station's technical setup, the digital signal may
> > > > > literally be completely separate from the analog. At WXXI-FM, for
> > > > > instance, our digital signal uses a separate transmitter, separate
> > > > > transmission line and separate antenna bays interleaved with our
> analog.
> > > > > It is possible (albeit not currently legal) for us to completely
> turn
> > > > > off our analog transmission chain and run only the digital
> carriers. If
> > > > > you were listening on an analog radio, you'd hear nothing on 91.5
> (or
> > > > > maybe even be able to DX something else on that frequency), but an
> HD
> > > > > radio would detect the digital carriers and still give you WXXI-FM
> when
> > > > > tuned to "91.5."
> > > > >
> > > > > The digital carriers operate at much lower power levels than the
> analog.
> > > > > Initially, digital operated at just 1% of analog, or 20 dB below
> carrier
> > > > > (-20 dBc). More recently, the FCC has started allowing stations to
> use
> > > > > higher power levels of 4% (-14 dBc) or even 10% (-20 dBc) of
> analog..
> > > > >
> > > > > So using KUOW as an example, let's say it's still -20 dBc. That's
> 100kW
> > > > > in analog and 1 kW in digital. If you're in metro Seattle, that 1
> kW
> > > > > digital is plenty to still ride right over anything else that
> might be
> > > > > coming on the adjacent channels of 94.7 and 95.1. If you're way
> down in
> > > > > Seaside, though, those 1 kW digital signals are DX: point a good
> antenna
> > > > > right at Seattle and you might get them strongly enough to decode,
> IF
> > > > > there's nothing else in the way on those frequencies. Point the
> antenna
> > > > > away from Seattle or disconnect it and you won't hear much of
> anything,
> > > > > as would be the case with ANY signal of 1000 watts from 100+ miles
> away.
> > > > >
> > > > > This leads to a bunch of interesting DX scenarios when you start to
> > > > > break it all down:
> > > > >
> > > > > For instance - let's say that you were a little closer to your
> > > > > semi-local on 94.9, enough so for it to be an un-nullable pest. But
> > > > > let's also say that your local 94.9 is analog-only. So you might
> have a
> > > > > spectrum that looks like this:
> > > > >
> > > > > 94.6 ---
> > > > >
> > > > > KUOW lower digital sideband, weak but with nothing else in the way
> > > > >
> > > > > 94.8 ---
> > > > >
> > > > > Your local analog 94.9, loud enough to overwhelm KUOW's analog
> > > > >
> > > > > 95.0 ---
> > > > >
> > > > > KUOW upper digital sideband, weak but with nothing else in the way
> > > > >
> > > > > 95.2 ---
> > > > >
> > > > > On an analog radio, all you'd hear is the local when you tune to
> 94.9.
> > > > > But when you tune an HD radio to "94.9," if it can hear those
> upper and
> > > > > lower sidebands, it will ignore the analog in-between...and so you
> might
> > > > > hear your local 94.9 in analog for a few seconds and then, when
> the HD
> > > > > decodes, you'll hear KUOW instead, because while your radio says
> "94.9,"
> > > > > it's really looking for signals above and below 94.9 to decode.
> > > > >
> > > > > There are all sorts of permutations on this that can happen when
> the
> > > > > dial is more crowded. It's easy, for instance, to think of
> scenarios
> > > > > where the spectrum is clear for a distant analog signal but its HD
> > > > > sidebands are overwhelmed by locals. For instance, I can easily
> hear 105
> > > > > kW WTSS 102.5 Buffalo in analog from about 70 miles away - but its
> > > > > 1050-watt digital carriers are completely obscured by locals WVOR
> 102.3
> > > > > and WLGZ on 102.7. If either of those locals goes off, there's
> WTSS in
> > > > > digital, because that bit of spectrum is suddenly open.
> > > > >
> > > > > Does that help make some sense of all of this?
> > > > >
> > > > > s
> > > > >
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