Stan By gosh that really is an old one. ABC very well could have been driven by a Rb ref. Though as I mentioned CBS was CS. So a bit hard to believe ABC and NBC were not. But I really simply do not remember. There had been a time when the networks were used for freq dissemination and thats why at least CBS had the CS. An alternate thought could be that it came from a local owned an operated station. And it was adjusted to the network. Some inside pixs would be pretty neat top see. Like you I chose to leave the USNO sticker on my sad but semi operational CS reference. Regards Paul WB8TSL
On Mon, Feb 20, 2012 at 7:48 PM, Stan Searing <timenuts...@gmail.com> wrote: > Does anyone know if ABC used Cesium or just Rubidium standards? > I have the Tracor 304SC shown in this URL: > http://www.bdairfield.com/stan/time-nuts/Tracor-304SC/IMG_4216.JPG > I assume the SC in the model number stands for the color subcarrier > frequency for NTSC: 3.579545 MHz. > The boards seem to be mostly hand wired on turret pins, so I don't think > they made very many. I usually try and clean up front panels and remove > non-manufacturer > stickers, but I thought the "ABC New York", "Rubidium 1" and "ADJ May 21 > 84" > were cool, so the stickers stayed. Under the top cover is a tag that says: > Model 304-SC > S/N 127 > Frequency relative to USFS -300 X 10 ** -10 > DATE 10-11-68 > > The front panel has a "5 MHz" output, while the back has a "3.58 MC" > output. > > I'm told this unit no longer works. KO4BB does not have the manual on his > site, if you know where one is, send me a link off list. > > If some folks know more about the history of network broadcast color > subcarrier frequency > standards, I think it's an interesting subject that would be worth hearing > more about. > > Stan > > > > On Wed, Feb 8, 2012 at 7:07 PM, paul swed <paulsw...@gmail.com> wrote: > > > All gone these days in the US. > > Indeed I can speak to the CBS network it was driven by CS references in > the > > 80s and 90s. > > I used CBS for aligning my references Xtal oven oscillators that were > never > > ever turned off in a large facility that uplinked all 8 CBS regions and > 22 > > other cable networks. > > > > Unfortunately few could get to that color burst signal as devices called > > frame synchronizers came into play from the 80s to the 90s. They would > > strip off that burst and insert the local reference of generally much > lower > > quality. > > > > As far as todays digital TV signals they can contain significant jitter. > > But its actually trickier then that and I honestly have to say I am not > > sure that you might not be able to get something useful. > > Several interesting points. Many of the television transmitters do use > GPS > > referenced sources. Its an interesting exploration. I simply don't have > the > > time though. > > Regards > > Paul > > WB8TSL > > > > On Wed, Feb 8, 2012 at 7:38 PM, jerryfi <jerryfi...@yahoo.com> wrote: > > > > > A bit off topic, but historically related.... back in the 70's, I > tapped > > > off the color burst > > > > > > oscillator in my TV (a Heathkit) to get a 3.579545.... MHz (315/88 > MHz) > > > source to > > > > > > calibrate my homebrew frequency counter. The TV's color burst > oscillator > > > was phase > > > > > > locked to the color burst signal on the broadcast signal (which was on > > > the "back > > > > > > porch" of the hori sync signals). Supposedly, the networks were locked > > to > > > Cesium > > > > > > standards traceable to NBS for LIVE broadcasts, such as news and > sports. > > > Taped > > > > > > programs, of course, were not usable as an accurate source. In any > case, > > > that signal > > > served my purposes at the time (providing a reference for calibrating > my > > > counter that > > > was more accurate than anything else available to me). > > > > > > I'm not sure if, what, or where analog TV is still broadcast, but I > think > > > there are still a > > > > > > few stations (low power) around. You might still be able to use that > > > signal, IF you can > > > > > > dig it out of your old analog TV. ;-) I do have analog tv's hooked up > > to > > > my cable > > > > > > box - I suspect that live broadcasts would still have an accurate color > > > burst, so maybe.... > > > > > > I think the other methods discussed here (ie, GPS) would provide easier > > > and more > > > > > > reliable timing sources. ;-) > > > > > > > > > Trying to locate the appropriate signal(s) in a digital TV today would > be > > > interesting. > > > > > > Just as a historical aside..... > > > > > > > > > > > > Jerry Finn > > > Santa Maria, CA > > > > > > > > > > > > > Date: Tue, 7 Feb 2012 18:01:26 -0800 > > > > From: Chris Albertson <albertson.ch...@gmail.com> > > > > To: Discussion of precise time and frequency measurement > > > > <time-nuts@febo.com> > > > > Subject: [time-nuts] Using digital broadcast TV for timing? > > > > Message-ID: > > > > < > > cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com> > > > > Content-Type: text/plain; charset=ISO-8859-1 > > > > > > > > GPS requires a good view of the sky, Hard to do in say the 7th floor > > > > of a 40 story building if you have no windows. I'm wondering about > > > > using the new digital TV signals for timing. > > > > > > > > I'm pretty sure there is time code in the signal and I'm pretty sure > > > > the bits are clocked at a very accurate rate. Also TV receivers are > > > > very easy to find and put "hooks" into. I'd bet the broadcast TV > > > > signal could be almost as good as GPS. > > > > > > > > The plan is to try and phase lock a local oscillator and use a very > > > > long time constant on the loop filter. I bet the TV transmitters > are > > > > locked to GPS and over a long enough time are as good as GPS. Also > in > > > > many cities there are many TV transmitters, should be able to take > > > > advantage of that. > > > > > > > > Before I try some experiments anyone want to tell me why I'm wrong? > > > > -- > > > > > > > > Chris Albertson > > > > Redondo Beach, California > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.