View Single Post
Old 7th Jan 2009, 10:21 pm   #4
ppppenguin
Retired Dormant Member
 
ppppenguin's Avatar
 
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
Default Re: 625-Line Television Broadcast Standards

As a general point, please distinguish between studio and transmission standards. The same 625 PAL studio kit is used in all 625 line countries. Including most of the SECAM ones because a SECAM vision mixer is an evil piece of kit. I know, I've been on the fringes of designing one. The SECAM countries, notably France, were enthusiastic early adopters of component signals in the studio. All studio stuff is now component, usually digital.

Transmission standards are another matter. There's a whole alphabet soup of them with many minor differences.

Quote:
Originally Posted by Synchrodyne View Post
Finally - for now, anyway - when was 625-line System N introduced? I would guess that Argentina was the first country to use this system, which “squeezed” a 625 line signal into a 6 MHz NTSC channel, I would imagine to ensure that the whole of South America (or nearly so, anyway) adhered to a standard channeling system. But the 6 MHz channel was perhaps a little ironic considering that in 1950, Channel E1, 41 to 47 MHz, was deemed unsuitable for 625-line television.
System N was a bodge. Argentina has 50Hz mains and so naturally used basic 625/50 TV. The channels planning however was American giving narrow channels. This didn't matter too much for monochrome, you just lived with a bit less resolution, but colour was a nuisance. Ended up with a roughly 3.5MHz subcarrier (as used for NTSC) but using PAL. Totally non-standard. Studio systems used ordinary PAL-B 4.43MHz subcarrier and transcoding to PAL-N was done at the inputs to transmitters.

South America is the home of oddball standards. Brazil uses PAL-M which is a properly engineered PAL 525/60 system. Not surprsingly the studios use NTSC and transcode at the tranmitters.
ppppenguin is offline