[opendtv] Patents and 60 Hz video with 50 Hz power

I've glanced at the messages I missed while I was gone, and I offer the 
following:

Patents - Many of you seem familiar enough with the U.S. Patent & 
Trademark Office site, but I've found even patent lawyers who don't seem 
to be familiar with the much more user friendly European Patent Office site:
http://ep.espacenet.com/search97cgi/s97_cgi.exe?Action=FormGen&Template=ep/en/advanced.hts

60 Hz video in 50 Hz power areas - It's found not only in Japan.  In 
1978, I was contracted to improve TV in Barbados.  The country had (and 
has) 50 Hz power but is in ITU Region 2, effectively restricting video 
bandwidth to 4.2 MHz, lower than the nominal PAL subcarrier.  Some South 
American (Region 2) countries decided to opt for PAL-M or PAL-N; 
Barbados initially opted for NTSC-N (50 Hz).  Naturally, there was not a 
lot of NTSC-N equipment available.  For international sporting events, 
they'd aim an NTSC-N camera at an NTSC-M (or PAL-B/G/H/I) monitor for 
standards conversion.

I suggested a change to NTSC-M.  The problem was the 50 Hz power.  So we 
ran some tests.  Japanese TVs had sufficiently filtered power supplies 
to cause no problems.  Older American sets had severe interference.  But 
a filter capacitor or two eliminated it.  A local company modified every 
older TV on the island, and they are now NTSC-M without problem.

TTFN,
Mark

 
 
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