); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY From: [EMAIL PROTECTED] Subject: Re: [time-nuts] Sputnik Date: Sat, 6 Oct 2007 22:05:15 EDT Message-ID: <[EMAIL PROTECTED]>
> ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > > In a message dated 10/5/2007 16:28:21 Pacific Daylight Time, [EMAIL > PROTECTED] > writes: > > >OK, not really a time related post...except for the clock in the CD > >player...which begs the question, any time nuts play with creating a > >more precise CD player using a precision oscillator? Think it would > >make a difference? I can see the selling point now "Our CD player is > >Rubidium controlled!" > > >Tom Frank > > > > Hi Tom, > > a related very interesting experiment is to take the Horizontal Sync signal > from an old Tube-type TV, and feed it to a frequency counter with GPSDO time > base (preferrably). > > Got to be careful about the high voltages inside the TV though! You can avoid hitting the coil and find it at a lower voltage if you dig around a little. > BTW: it's not 15374KHz, there are some significant decimal digits (I don't > recall the formula to calculate the frequency exactly, but it was the total > number of frame lines multiplied by 59.94Hz or so). The field-rate is 60000/1001 Hz and frame-rate is 30000/1001 Hz exactly. This results in 525x30000/1001 Hz as line frequency, exactly. Toss in the tolerances allowed, naturally. The magic number 1001 is actually 7*11*13 and 525 is actually 3*25*7 so a reduced form becomes 3*25*30000/(11*13) or 2^4*3^2*5^6/(11*13) which still is a horrible number. Still, the magic number is better than the magic number 193 for DS1 which is an actual prime number. > Then you can test how accurate the broadcasters' 27MHz reference clock is. This is indeed a magic number since it is 1716 (11*12*13) times the NTSC line frequency. It is at the same time 1728 (2^6*3^3) times the PAL line frequency. You really want to know these frequency relations. > One would be surprised how inaccurate(!) some broadcasters are, and how much > drift some Satellite providers have. You are in for a supprise when it comes to the MPEG-2 TS time-stamp data stability then. :-) > A lot of the stability is dependent on the receiver of course, and how well > the receiver's VCXO locks to the Broadcaster. Natuarally. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
