Hi Steve, Dave,

 

as far as I know, the PAL colour subcarrier is supposed to be locked to the line and field rates, but with an intentional offset from an integer 25 Hz multiple to provide some "blurring" of possible moiree effects. Ideally, the line frequency should be accurately on 15625 Hz. The German ZDF timebase used to be derived from the PTB atomic clocks in Braunschweig and could be traced to UTC, but nowadays analog terrestrial TV transmitters have pretty much disappeared here.

 

Best regards,

Markus, DF6NM

 

-----Ursprüngliche Mitteilung-----
Von: VK2ZTO <[email protected]>
An: [email protected]
Verschickt: Di., 6. Okt. 2009, 13:24
Thema: LF: Re: Re: What is on 499.993 kcs ?

G'day Dave, 
 
Yes - I did that calculation but came up with 500002.81 Hz - not 499993 Hz. 
 
Still - that seems the most likely explanation as it is very stable. 
 
Thanks. 
 
73 Steve VK2ZTO (VK2XV) 
 
----- Original Message ----- From: "Dave Sergeant" <[email protected]> 
To: <[email protected]> 
Sent: Tuesday, October 06, 2009 9:34 PM 
Subject: LF: Re: What is on 499.993 kcs ? 
 
> > Or more likely the 32nd harmonic of the 15.625kHz TV line ocillator > rate. UK, UA and VK all use the 625 line PAL standard (though parts of > USSR are Secam). The line rate is actually locked to the colour > subcarrier of 4.43361875 MHz which may account for the 7Hz shift at > 500kHz. 
> > 73 Dave G3YMC 
> > http://www.davesergeant.com 
>