From: apogosso@tpg.com.au   
      
   "Don Pearce"  wrote in message   
   news:4e2a6ab0.208292@news.eternal-september.org...   
   > On Fri, 22 Jul 2011 23:41:18 -0400, Don    
   > wrote:   
   >   
   >>Don't forget SECAM, System European, and Contrary to Any other Method   
   >   
   > The French. Says it all, really.   
   >   
   No only the French, but the Russians originally chose SECAM too.   
      
   I do not know why the French preferred SECAM to PAL, but for the Russians   
   the answere was obvious. The thing is, colours in SECAM are *least* affected   
   by nonlinearity of amplitude/phase response of the signal chain (around the   
   colour subcarrier(s), which are two in SECAM).   
      
   For example, in the direct vicinity of a TV station a good NTSC TV set will   
   potentially give the best picture quality, because colour demodulation is   
   linear, and each line is independent. PAL will be the second because of   
   averaging of two lines, and SECAM the worst because FM colour subcarrier   
   modulation inherently is limited by slew rate, and colour transitions are   
   not that sharp.   
      
   And now suppose you pass your TV signal through a couple of analogue   
   radio-relay links. Each would introduce a significant phase shift (up to   
   +/-45deg), especially the Russian ones, where everything electronic was of   
   inferior quality.   
      
   NTSC will lose its colour completely.   
   PAL will preserve colour, but will lose saturation or the colours will be   
   "pulsating" because of phase jitter.   
   SECAM will still show correct well saturated colours. Not surprising,   
   because though phase might be unstable intermittently, the frequency on   
   average does not change. The colours will be more noisy (phase   
   jitter-->frequency jitter), transitions will not be as crisp (like the   
   picture will be rather coloured than colour), but on large areas the colour   
   reproduction and saturation will be the same as in the original studio   
   material.   
      
   No wonder the Russians in those days chose SECAM because vast size of the   
   country assumed lots of radio-relay links.   
      
   Now when everything is digital and satellite, PAL is the most common in   
   Europe and better than SECAM, and Russia switched to PAL.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)