Re: [IRCA] "HD" DX?

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

> No, I haven't gone over to the dark side, but I did get a chance to
borrow a
> Boston Acoustics "HD" receiver and play with it a bit.  I'm not in
range of
> any FM IBOC stations, so I've mostly been trying it out on AM.

  The most interesting reception was of WDCD (1540, Albany NY, 205 miles
> from me), where I actually received the digital audio stream, for a
grand
> total of about 5 seconds.  There wasn't a huge change in audio
quality - the
> striking change was the sudden disappearance of co-channel
interference
> (mainly from CHIN).  Aside from that one brief burst, I had zilch
digital
> audio decoding from a host of strong IBOC signals.
>
> So, is this the first reported instance of AM IBOC audio reception via
> skywave?  Even if I can claim that dubious distinction, it certainly
doesn't
> change my opinion, expressed years ago, that AM IBOC would be an
absolute dud
> as far as DX'ers are concerned, and is a train wreck in general.
>
> Barry
>
> -- 
> Barry McLarnon  VE3JF  Ottawa, ON
> _______________________________________________

Barry, you and Craig Healy are the only reports I know of
that have had any HD audio (call letters flashing on the
window don't count). I was quite surprised at how _fast_
the call letters will pop up in the window, and how _long_
it takes to sync to the audio. I'd think that if there is a fade
or other anomaly more often than once every 7 or 8 seconds,
you'll _never_ get skywave HD.

I'm starting to think the change in audio quality on AM will
be determined by the quality of the original program feed.
Probably Limbaugh, on WFLA is a better "demo" since
they seem to have a high quality feed out of the EIB facility.
I'd bet that a locally originated talk pgm would not be as
much of a difference, e.g. mono only, etc - or does everyone
on AM originate audio in stereo now?

The most interesting demo I could think of, right now, would
be for you to have access to an Accurian and try that set out
_side by side_ with a BA and get a good determination of how
much the sets differ in reception quality. I think this is useful
to factor in the true variable of rcvr performance against the
"constant variable" of how much the HD transmission
medium deviates from plain analog. Accounts such as yours
seem to consistently say that the HD skywave is very
fragile. Would the BA and the Accurian behave similarly,
if run side-by-side and hearing the same skywave signal?
IOW would you get the same 5-second decode on both
sets at once?

If the indicator for decode was a DC level available
somewhere inside the set, this could be run to a 2-track
chart recorder so that one could do a long unattended capture. I
have no idea if such a signal is even available on one of
the pins anywhere inside the set. The HD icon on the
window might work if you found the driver lead. Should
be do-able with a hi-Z scope.

I wound up keeping my Accurian, after all. I did send for the
rebate timely and made sure to photocopy all three things
they asked for (sales slip, and rebate form from RS, and
the UPC code cut from the carton). If, by some chance I
get denied on the rebate, it will be a subject of posting
on BE and RT. The main reason I kept it is that I missed the
return deadline which was right at Xmas. I still want to
do some testing of edges of coverage on the various
AM stations, all with the included "loop". I don't much care
about FM in this manner, the secondaries are attracting
all the interest there.

Here in TPA, 620 WDAE and 1250 WHNZ are also now on HD,
however 820 WMGG has had it turned off for about three
weeks. I called them after a few days of it being off and they
said it "would be back by that weekend", but when I checked,
along with others, it was off. It appears that the CC stations
are the ones using it here. I have little doubt that 820 will
have it on again. The audio difference (analog vs HD) on
their music format was much more noticeable than any of the
three gasbag talkers it's now on on the CC stations - what
a waste.

The local SBE chapter is planning a meeting about HD soon
so that should be fun. I'll have to marshal some info to share.

- Bob                     2223 est





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