On Sat, 12 Mar 2011 13:13:52 -0600, "
wrote:

On Sat, 12 Mar 2011 13:31:36 -0500, mm wrote:

On Sat, 12 Mar 2011 07:49:09 -0500, "Ed Pawlowski"
wrote:


"mm" wrote
I thought that letting a VCR or DVD recorder or TV scan for channels
was only to compile a list in advance of stations a device
could receive, by checking out every channel and noting which had
signals.

Right, that is usually a one time deal and then the TV has a memory of those
channels. You can usually edit the channel listing also. By eliminating
the ones you never watch, the TV will skip over them when you hit the UP or
DOWN buttons.



And that pushing 1 3 on the remote would go to channel 13 whether one
had scanned for channels or not, whether digital station frequencies
had changed since the last time one scanned or not.

Yes

As effectively as
if one scanned the whole spectrum, and then channeled up or down to
get to 13.

Am I right about the paragraph just above?

Yes



And that for timed recording, when the dvd recorder goes to channel 13
directly, it looks for it if necessary, just like scanning does.

Don't think so. It will go to 13 but it won't scan looking for it AFAIK


And
if it gives some reception, though bad reception, even though the
transmitter is only 10 miles away, it's not because it's off
frequency? But because the signal is bad.

I don't have OTA so I'm not going to comment


Or are digital tuners different from analog, in that scanning first
and whenever the channel frequency changes is essential?

Why would the frequency change?

The tv station can change the frequence it uses. They do this on rare
occassions I think.

Why would they do that? Sure it happens, perhaps once, in a station's life
but it takes permission (or direction) from Washington to do it.

Yes, to cooperate with other stations when the FCC says to.

Or, maybe a power failure at my house could cause it to forget things.
IIRC, unplugging an analog tv long enough would cause it to forget
*which* stations are preset, but of course it would have no trouble
going to one directly.

Generally they default to all enabled. You then program in the channels to be
skipped.

If it really forgets "everything" it has to scan before it knows the
statiosn. Of course brand new digital devices insist on scanning,
come to think of it, I think, (and some analog ones did too, but only
like they insisted on your putting in the correct time. It wasnt'
necesary to make the tv work.)

What happened is that one of 3 network statiosn whose transmitting
antennas are less than 10 miles away stopped coming in. After about 3
days, I emailed them and they wrote back a short nice letter saying
with some tvs I need to rescan and would I try that please. (In other
words, his transmitter is working as normal, he thinks)

After I wrote them, I noticed that another of the 3 network stations
wasn't working and the third sometimes didn't, EVEN though the
independent stations in DC, 45 miles away were working.

Now I'm wondering if my antenna amp is malfunctioning and putting out
too strong a signal for the strong stations. Hmm, there is a way to
test that without going into the attic.

If it's a strong station try a wire stuck in the back of the set.

Exactly. I should have thought of that. I'm getting slow-witted
with age or distraction.