[sdiy] A Frequency Standard for Poor People?

[Magnus Danielson]

From: Grant Richter <grichter at asapnet.net>
Subject: Re: [sdiy] A Frequency Standard for Poor People?
Date: Tue, 16 Dec 2003 11:08:44 -0600
Message-ID: <BC04983C.2A8%grichter at asapnet.net>

> on 12/15/03 5:14 PM, Magnus Danielson at cfmd at bredband.net wrote:
> 
> > 
> >> This is so "hum bars" (power supply noise) are stable. If you see a
> >> "hum bar" drifting slowly, it means the broadcast source is reference
> >> locked.
> > 
> > Actually, this is the reason why the US runs at 30 / 1.001 so that the color
> > material does not lies on overtones of the powerlines. The NTSC is extra
> > sensitive to phase shifts as compared to PAL. In PAL a certain off-frequency
> > aspect is also done, but not as drastic and in the end it works well.
> > 
> > Cheers,
> > Magnus - with a finger in the video jam pot - too...
> 
> Maybe I should look for a more recent reference than my 1967 ARRL handbook
> ;^)

Maybe you should... ;O)

> This is the first I heard of the frequency offset. That would be a tweak for
> national broadcasters?

No, no tweak.

> OT but interesting to vidiots. My supervisor, Dale King said he was
> operating a video camera on the deck of an aircraft carrier during the
> Battle of the Coral Sea. They were sending real time video to the CIA, who
> was sending back tactical analysis. At that time, video was a classified
> technology. Pretty high tech for WWII. Dale also called video monitors
> "kinescopes".

Video existed in early precursors prior to the war, but surely lots of
development where done there too during the war.

> The studio I worked at had an oven stabilized crystal master synch box just
> chock full of TTL chips (which Dale built). Boy did it get warm too. The
> off-site cameras were line locked. Then the tapes were played on 3/4"
> U-matics which had a phase lock input that would servo the head motors to
> the master synch box. This only gave vertical lock but not horizontal, so
> you could crossfade between cameras but not tape decks.

Indeed how classic analog setup works. TV-production is seriously synchronous
production. Everything is locked, and when it isn't there is a big hazzel until
you "got it". Going digital, compressed and all that solves exactly nothing of
those problems, just helps you to forget to do the "right stuff" and you end
up with a bigger mess than ever... (sigh!).

Cheers,
Magnus