AJ Lake wrote:

...
I experience the same phenomenon. My antenna is a UHF indoor bow tie dipole.
(All my HD channels are currently on UHF.) I am about 30 miles from the TV
tower which is at 1200'. My HDTV set can show signal bars like a cell phone.
Without moving the antenna or other surrounding objects, the signal will
sometimes slowly vary by one or two bars. If it goes down too far the
picture breaks up and quits. At other times the same station will give a
solid 3 or 4 bars.This happens on all channels. Perhaps atmospheric
movement? Lots of dust here in the desert. Any other ideas?


Yes, ducting and "ghosting" of the signal(s) due to reflections, etc.--I
can see these as being a REAL problem. From your description(s), sounds
like "they" just took the exact-same
technology/encoding/decoding-schemes and implemented them onto broadcast
.... what works well with cable (a relatively "stable" signal NOT prone
to the effects stated above ...) may not work all that well with
broadcast ... sounds like some "upgrades" are already in order.

I have just assumed, up to this point, that the digital HDTV signal is
"packeted" ... however, unlike our broadband modems and satelite
internet, you cannot request for a corrupt packet to be "resent" to your
TV ... however, I am wondering if corrupt packets (or, seriously
degraded ones) are just being "tossed" rather than passed along to the
video/audio circuitry? Perhaps the software should assume that no
matter how degraded (or, at least seriously degraded packets) should be
passed on and the viewer be allowed to determine if it is of enough
worth, or not? It almost sounds like this would be preferable to
no-signal-at-all. But then your description of "the bars" beginning to
degrade would soon reach a point of "un-viewable signal" anyway?; so,
at this point, perhaps no-signal-at-all is preferable ... hmmm, I wonder?

I have not had a chance to "experience" broadcast HDTV yet ...
however, the cable HDTV is much improved over old analog ...

I have cable HDTV on my other set in the family room. Surprisingly (to me)
the broadcast HDTV picture is superior in quality to the cable HDTV picture.
Perhaps Cox is using more compression to squeeze more channels in the line.

Hmmmm, you have me all the more anxious to have HDTV implemented in my
area ... LOL!

Regards,
JS