[time-nuts] WWVB d-psk-r down conversion method...

Alexander Pummer alexpcs at ieee.org
Tue Sep 23 13:11:08 EDT 2014

there is an interesting side effect with that phase modulation: in case 
the crystal filter is "narrow enough" --to use for the old AM format-- 
the phase change creates an additional AM modulation, if you take in 
consideration that effect by the decoding the modulation, you could 
recover the time information "despite" of  the presence of the PSK.....
Question: as fare as I am informed there is no chip/system available to 
correctly decode the new signal form, what was the purpose of the whole 
modulation format change?
The old AM format was happy with cca 200Hz bandwidth to recover the time 
information, which was utilized in many professional receivers, which 
used a crystal filter for 60kHz, for the PSK format the required 
bandwidth is at least five times wider, so crystal filter would be 
problematic and much more costly, the higher required bandwidth brings 
also more noise ....actually where is the advantage of the new 
modulation scheme?

On 9/23/2014 9:16 AM, Burt I. Weiner wrote:
> Charles,
> If I recall correctly, the original point of the d-psk-r was to cause 
> the clocks to again read the correct time, not maintain their use as a 
> frequency standard.  I have a Symmetricom 8170 that I used to use only 
> as a clock to tell the time of day.  Since WWVB's addition of the PSK 
> coding, it's only good to watch the pretty blinken lights.
> Burt, K6OQK

More information about the time-nuts mailing list