[sdiy] A Frequency Standard for Poor People?

[Grant Richter]

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
;^)

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

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".

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.