Re: [Swprograms] Promo of Channel 6 (U.S.) as low end FM band

[Joseph Buch <joseph.buch@xxxxxxx>]

At 10:55 PM 05/24/2005, Steve Coletti wrote:
>Correct me if i'm wrong, but isn't the standard for the TV stereo system a
>15.575kHz pilot, the same as the NTSC video horizontal lock pulse/blanking?

15.750 kHz was the horizontal scan frequency back in the days of black and white TV.  With the advent of NTSC color the frequency had to be changed to 15.734 kHz as I remember.  The frequency shift was necessitated by the need to have sidebands of the horizontal scan frequency interleave with the color information sidebands.  The purpose of this interleaving in the frequency domain was to minimize the apparent crosshatch one sees in highly saturated colors from the color 3.579545 subcarrier frequency in the luminance video.  That change in horizontal scan frequency necessitated the vertical field rate to also be shifted slightly from 60 fields per second to 59.94 as I remember.  I will check these numbers when I can get to my reference book.  Right now I am away from home.

I have no specific recollection about the frequency of the TV stereo pilot but I believe you are correct that it is locked to the horizontal scan frequency.  It would be interesting to see if a properly aligned stereo tuner would demodulate the stereo on this station.

Joe Buch 


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