[time-nuts] Sputnik

[Magnus Danielson]

From: SAIDJACK at aol.com
Subject: Re: [time-nuts] Sputnik
Date: Sat, 6 Oct 2007 22:05:15 EDT
Message-ID: <cc1.1ceecd14.343998db at aol.com>

> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+magnus=rubidium.dyndns.org at febo.com RETRY
> 
>  
> In a message dated 10/5/2007 16:28:21 Pacific Daylight Time, ka2cdk at cox.net  
> 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