"Geoffrey S. Mendelson" wrote in
:

mm wrote:
For 60 years, USA tv signals and European ones, etc. were not
compatible.

Sort of. Multisystem TV's Were common in the 1980's. There were only 4
systems of video, although there there were lots of ways to transmit
them.

They were NTSC (60Hz, 3.57mHz color carrier), 50Hz PAL, 60Hz PAL, and
50Hz SECAM. There also was 405 line UK TV (dropped in the early
1980's) and NTSC 4.43 (same signal, color carrier moved to make
cheaper playback equipment).

I still have a 1985 Sharp TV set that will play both NTSC versions,
All PAL versions, and SECAM from anywhere except France. I had a 14
system VCR that would play and record French SECAM and a different TV
set to play it on.

My kids use a 21 inch 4:3 CRT that is simialr, except that it does not
have a French tuner. It added component and S-video instead.

Did they make digital tvs compatible from the US to Europe to Asia to
Australia, etc?

I also have had VCRS that included digital TV standards converters.
They were multisystem VCRs with the conversion feature added on top.

But digital TV was not needed, analog TV's played the signals fine. It
was just a matter of adding the correct hardware.

I think they should have. If not, is it only the 50 versus 60
vertical scan rate that was the problem?

The color carrier. NTSC used a phase modulated color carrier at
3.5mHz. PAL used a similar carrier at 4.43mHz. To fix a problem
noticed in NTSC signals the BBC adopted the practice (which was in
the proposed NTSC spec but dropped to save money) of alternating the
phase every other line, hence the name PAL (Phase Alternating Line).

TV sets which would lock on 50Hz or 60Hz signals as appropriate were
not a technical issue and by 1980 almost all made would anyway.

SECAM used a different decoding method, but those chips were easily
found, and it was common to see TV sets and VCRS that would
play/record SECAM signals broadcast using PAL over the air standards.
Eastern Europe (Warsaw Pact countries), most Arab countires, China,
and the USSR used some form of SECAM encoded signals with PAL
frequencies.

The French used a different channel spacing, and AM sound, which made
their SECAM signals impossible to tune with the correct tuner. It also
made Eastern European TVs worthless in France and vice versa.

I don't think I've read anything about this.

You either must have head your head under a rock, or live in the US
and never traveled out of there.

Note that I had several multisystem TV sets, VCRS (BETA and VHS), and
even a portable combination AM/FM/SW receiver and TV set that looked
like a Star Treck tri-corder, all puchased in the 1980's in Philly.

Geoff.


AFAIK,the TV systems are STILL incompatible;
Europe uses different broadcast modulation schemes and different frequency
assignments.

--
Jim Yanik
jyanik
at
localnet
dot com