🚀 go-pugleaf

In article <1992Oct03.042813.15261@ssc.com>, markz@ssc.com (Mark Zenier) writes:
> In article <1992Oct1.165659.8131@bnr.ca> mwandel@bnr.ca (Markus Wandel) writes:
>>Say that everything was based on square waves, and that you started out
>>with a 38KHz clock waveform.  Based on this clock, you alternately select
>>the left or the right channel for transmission, transmitting a sequence
>>of samples L, R, L, R, L, R, etc.  You also add a 19KHz pilot tone at
>>half the clock frequency.
> 
> Well, damn.  If you plot it out on paper, it does work.  You end
> up the L+R, added with the L-R (or R-L) times the 38 kHz subcarrier.
> 
> Getting the 19 kHz phase just right could be a problem, as would getting
> the lowpass filter needed to round off the sharp edges without messing
> up the phase response.
> 
> Did any commercial gear work this way?

Someone else mentioned that at least one of Heath's top-of-the-line receivers
did.  And many (most?  all?) recent color tvs demodulate the 3.58 MHz chroma
subcarrier this way. 

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh