🚀 go-pugleaf

> 
> 1. To transmit stereo FM signals first they add the left channel (L) to the
> Right channel (R) Then they subtract L-R then they transmit the addition of
> two signal (L+R) after passing through 18KHz low pass filter using regular
> FM transmite. This way every body can receive the "L+R signal", then add
> 18KHz to the L-R signal and send it through the same channel. Now, all the
> receivers that have stereo capability isolate this signal first, subtract
> 18Khz from it then add and subtract it from L+R signal:
> 
> (L+R)+(L-R)=2L
> (L+R)-(L-R)=2R
> 
> 2.  As you can see, sending the signal this way needs large band width and
> AM by FCC regulation only permit less than 10KHz band width.  There is
> not enough space for the signal itself, let alone pigibacking another
> signal to it  Off course, these days using digital technology you might
> compress the signal before sending and do a lot of other things to it.
> Therefore, it might be possible to this today if everybody agree on the
> same procedure.  Today, we have motorola standard, RCA standard  etc...
> 
>                   With highest regards,
>                        Babak   Sehari.

MALE BOVINE ORGANIC BIOLOGICAL ROUGHAGE!!!!!


You seem to ignore the 38Khz double sideband suppresed carrier portion
of the the signal (which actually carries the L-R signal).  You have
a total misunderstanding of the 19.000 KHz stereo pilot signal which
is uused solely to phase lock the oscillator used to demodulate the
38 KHz  DSSC L-R signal and incidentaly to light the little stereo lamp 
and activate auto-mode select in recivers so equipped.

You ignore the fact that the bandwidth usedby the carrier is 
exactly the same for FM mono or stereo (+/- 75 Khz of carrier). 
You ignore that the AM DSSC is used to modulate the
FM carrier in exactly the same way (ignoring pre-emphasis) as the
L+R main channel audio.  Aside from that, you ignore that AM stereo
generally uses variations of phase modulation to transmit the 
required audio difference signal(s), and the political reality
that AM stereo was stiffled tremendously by the FCC unwillingness
to make a decision on ONE standard for AM stereo transmission.

The FCC instead took the cowards way out and decided to "LET THE
MARKET PLACE DECIDE!"  This gave receiver manufacturers no sense
of direction as to where to spend their limited research and
development time and dollars since no one wants to put money into
something that MIGHT only get 1/4 of the market, IF that.

With slow receiver penetration, transmitter conversion/replacement
was also slow for the same reasons.

The slowness of AM stereo to penetrate the market has nothing
nowadays to do with technical standards, only financial and
political realities.

Joe Pyrdek
Edinboro Univ.
Edinboro PA