[ntp:questions] Re: Why phase modulation
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:
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
>>NTP Time Server with PZF receiver:
>>Radio Clock Module
>>(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 :-)
More information about the questions