[ntp:questions] Re: Why phase modulation

Heiko Gerstung heiko.gerstung at meinberg.de
Tue Jan 10 15:14:10 UTC 2006


Rob van der Putten wrote:
> Hi there
> 
> 
> Heiko Gerstung wrote:
> 
> 
>> From our DCF77 info page (http://www.meinberg.de/english/info/dcf77.htm):
>>"In order to increase the accuracy of the demodulated time marks, the
>>carrier of DCF77 is additionally modulated with a pseudo-random phase
>>noise. The pseudo-random sequence has a length of 512 bits which are
>>transmitted in the time interval between the AM marks. Due to the
>>pseudo-random characteristics of the sequence, the mean deviation of the
>>carrier phase is still zero. The phase modulated carrier can be received
>>with a larger bandwidth. Correlation algorithms known from satellite
>>techniques let PZF receivers determine the correct time with an accuracy
>>of some microseconds which is much superior to the accuracy achieved by
>>standard AM receivers."
> 
> 
> Any more in depth info?

The PTB only provides a few sentences here:
http://www.ptb.de/en/org/4/44/442/_index.htm

But they offer to give you more detailed informations on request, so 
maybe you just want to contact them directly.

> 
> 
>>AFAIK we (Meinberg) are the only vendors offering such a technology. See
>>for example:
>>
>>NTP Time Server with PZF receiver:
>>http://www.meinberg.de/english/products/lanpzf.htm
>>
>>Radio Clock Module
>>http://www.meinberg.de/english/products/pzf510.htm
>>
>>(this one can be ordered as a standalone rack-mountable system with
>>power supply and housing)
>>
>>and any other products with a "PZF" in their name :-)
> 
> 
> Found those.
> I was just wondering if there are any more.
As I said, I do not know any other vendors, but if you find any, please 
let me know :-)

Regards,
Heiko




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