🚀 go-pugleaf

jeh@cmkrnl.com writes:
: 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.  
: > 
: > 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. 

Sorry, the question should have been: Do commerical FM stereo transmitters
work this way?  (I've been trying to come up with a cheap stable FM stereo
exciter for a couple of years.)

My speculation is that, within the broadcast community, this technique
is well known.  But outside that, most people are working off the
description from the FCC regulations, which is the frequency domain
description.  (Since they are more interested in bandwidth and 
interference than simple design.)

So you end up with things like the North Country Radio/Graf and Sheets
transmitter (Radio-Electronics March and April 1988) which used a
balanced modulator for the 38 kHz subcarrier and was overly complex.
And didn't work well, according to a friend who built one.
(Which makes sense, keeping your phase responses right through all
that would be hard.)

Mark Zenier  markz@ssc.wa.com