Subj : Re: Ham Radio Digital Mod
To   : Ed Vance
From : Holger Granholm
Date : Tue Nov 07 2017 09:30 pm

In a message on Tuesday 11-06-17 Ed Vance said to Daryl Stout:

Hi Ed,

I'm just busting in, not because I have any experience of digital Ham
Radio, but I have experience of TV.

EV> I watch Television using a Digital TV Convertor box.

Here called Digibox'es.

EV> I remember that back when Analog Television was being broadcast if
EV> the Picture messed up the sound portion could still be heard on
EV> those TV Sets

That is correct. The same was true with the so called digital channels
via Digiboxes.

Those old Digibox channels are now called analog and are still available
on modern TV sets, along with true digital and HD channels.

In most cases when the digital/HD signal becomes too weak to give a
picture, the sound also disappears. In rare cases there may be sound.

EV> One of the local Amateurs who owned a TV and Radio Repair Shop
EV> talked about taking courses and buying Test Equipment so He would be
EV> able to service Digital Television Sets when they needed any fixing.

There's no special test equipment needed, except a signal generator that
can give a digital TV signal, and in case you do service on antenna
distribution nets, a field-strength meter that is compatible with HD and
digital signals.

EV> Have You noticed if there any lapses or delays to the transmission
EV> that You are listening to when You're using any of those Digital
EV> Modes wheather during a QSO or You're SWL'ing the Band?

What I have noticed is that the more compressed a TV-signal is, the more
is the time delayed. Finnish TV hasn't noticed that or corrected it, but
swedish TV has.

The delay is only in the class of seconds but still irritating.

We did also have some "digibox" channels compressed with a MP4 compres-
sion, and even there the delay was greater than the uncompressed digibox
channels.


73 es GN de Sam, OH0NC

aka Holger


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