16 Jun
2002
16 Jun
'02
1:15 p.m.
Hi,
Dave Woodman <dave(a)naffnet.org.uk> said:
John Honniball wrote:
The other way about ;-) Interference on PAL produces unobtrusive black
blobs as opposed to annoying "snow".
--
Cheers,
Stan Barr stanb(a)dial.pipex.com
The future was never like this!
Dave Woodman wrote:
You're welcome!
Except, of course, in those large parts of the world that use PAL, and other
parts that use SECAM, and....
Thanks for pointing that out!
Just to add a bit of technical info, in the PAL-I system, as used
in the UK, the composite video is inverted before being amplitude
modulated onto the carrier. That means that the sync pules are
peaks of high-amplitude radio signal and bright areas of the
image are low-amplitude signals. The reason for this is to
reduce the average RF power required at the transmitter. Quite
a clever idea, really.
There is also another benefit:- any impulse noise that interferes with
the video results in a white pin-point on the picture, as oppose to a black
blob (especially when the HT is poorly regulated...).