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From: bprice@bmcg.UUCP (Bill Price)
Newsgroups: net.analog
Subject: Re: Stereo TV, a request
Message-ID: <2012@bmcg.UUCP>
Date: Tue, 26-Nov-85 19:52:30 EST
Article-I.D.: bmcg.2012
Posted: Tue Nov 26 19:52:30 1985
Date-Received: Fri, 29-Nov-85 21:53:18 EST
References: <410@drutx.UUCP>
Reply-To: bprice@bmcg.UUCP (Bill Price)
Organization: Burroughs Corp. ASG, San Diego, CA.
Lines: 95

In article <410@drutx.UUCP> sef@drutx.UUCP (FarleighSE) writes:
>I need the specification for stereo broadcasting that is currently
>in use for Television.

The following is summarized from the FCC bulletin on Multichannel
Television Sound, as reprinted in the MTS Deskbook of BM/E (Broadcast
Management/Engineering) magazine, October, 1985.  The FCC bulletin is
Office of Science and Technology Bulletin #60 (OST60), and begins as
follows:

	This bulletin contains those technical specifications for
	the BTSC System as presented to the Federal Communications
	Commission by the Electronics Industries Association. 
	These specifications are presented herein pursuant to the
	Report & Order in BC Docket 21323 adopted March 29, 1984...

	...The purpose of this Bulletin is to present the BTSC
	specifications which in accordance with FCC Rule [section]
	73.682(c)(3), are required to be met when a broadcast
	station transmits an emission at 15,734 Hz.

From here on is my summary:  errors and omissions may occur, so be warned...

All of this pertains if and only if the station includes the pilot signal
in its aural (audio) carrier.  The pilot signal is at the horizontal
scanning frequency, H, frequency modulating the aural carrier at 5KHz+-.5KHz 
deviation.  The nominal value of H is 15734Hz.

The main channel signal is the stereo sum, L+R, FMing the aural carrier at
25KHz recurrent-peak deviation, with 75-microsecond pre-emphasis.

The stereo-channel signal is the stereo difference, L-R, modulating a
subcarrier of 2H.  The modulation is double-sideband, suppressed carrier.
The residual subcarrier, with no modulating L-R signal, generates no more
than .25KHz modulation of the aural carrier.  The modulated subcarrier FMs
the aural carrier at 25KHz recurrent-peak deviation.  The subcarrier is
phase-locked +-3 degrees with the pilot, with subcarrier zero-crossings at
the positive-going zero-crossings of the pilot.

The Second Audio Program (SAP) FMs a 5H subcarrier to 10KHz peak deviation.
The modulated subcarrier FMs the aural carrier to 15KHz max deviation.

L-R and SAP signals are encoded before modulation, with fixed pre-emphasis,
wideband amplitude compression, and spectral compression.  The pre-emphasis
function is
         (jf/0.408)+1     (jf/2.19)+1
F(f)  =  ------------  *  -----------
         (jf/0.0354)+1    (jf/62.5)+1

The amplitude compression, in dB, is c*P(f), where 

C(T)  =  sqrt [ integral(-inf, t) S**2(u)exp((u-t)/T) du ]

S(u) = the signal

c = 20*log[10](C(34.7 ms)/R)

               (jf/0.0354)
P(f) = -------------------------------
       [(jf/0.0354)+1] * [(jf/2.09)+1]

In the amplitude compression, the zero dB reference level (R) is 8.99%
modulation of the subcarrier at 300Hz, resulting in 14.1% actual modulation
after encoding.

The spectral compression function, S(f,b), is

          1+(jf/F)  (b+51)/(b+1)
S(f,b)  = -----------------------
          1+(jf/F)  (1+51b)/(b+1)

F  = 20.1KHz

b= C(11.4 ms) * Q(f) / r

                                (jf/5.86)**3
Q(f) = ---------------------------------------------------------------
       ((jf/7.66)**2 + (jf/7.31) + 1) * ((jf/26.9)+1) * ((jf/3.92)+1))

The zero-dB reference level, r, is 5.16% subcarrier modulation at 8 kHz.

***************

That's enough for this time.  The worst is over:  what's left is some
performance specs.  After all that heavy frequency-domain stuff that I
don't understand, I'm ready to ask:

1.  Does this really mean anything to anybody on the net?  If so, what?

2.  Is this what you thought you were asking for?

3.  Does anybody here care any more?
-- 
--Bill Price  uucp:  {Most Anybody}!sdcsvax!bmcg!bprice
              arpa:? sdcsvax!bmcg!bprice@nosc