sef@drutx.UUCP (FarleighSE) (11/01/85)
I need the specification for stereo broadcasting that is currently in use for Television. Scott E. Farleigh AT&T Information Systems 11900 N. Pecos St. Rm 30L27 Denver, CO 80234 (303) 538-4904 ..!drutx!sef
bill@videovax.UUCP (William K. McFadden) (11/13/85)
In article <410@drutx.UUCP> sef@drutx.UUCP (FarleighSE) writes: >I need the specification for stereo broadcasting that is currently >in use for Television. You might try looking at a couple of articles from IEEE. Specifically, IEEE Transactions on Consumer Electronics Vol. CE-30 pp. 236-240 (Aug. 1984), and pp. 633-640 (Nov. 1984). The first article discusses the BTSC transmission/reception standard; the second discusses the dbx companding system used for stereo TV. I posted an article to net.ham-radio some time ago that could serve as an introduction to stereo TV broadcasting. Mail me if you want a copy. -- Bill McFadden Tektronix, Inc. P.O. Box 500 MS 58-594 Beaverton, OR 97077 UUCP: ...{ucbvax,ihnp4,uw-beaver,decvax}!tektronix!videovax!bill GTE: (503) 627-6920 "How can I prove I am not crazy to people who are?"
bprice@bmcg.UUCP (Bill Price) (11/27/85)
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