[time-nuts] WWVB D-PSK document

[Bob Camp]

Hi

But can you ignore the WWVB signal swing? The beast flips a cycle (or more) as you hit sunrise or sunset. A cycle at 60 KHz is a lot of ppm. Weather this happens fast enough to actually turn it into a tuning issue is the question.

Bob

On Mar 31, 2013, at 7:36 PM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> Hi,
> 
> Uhm, yes. You want your pulling-range to handle all the drift and tempco you reasonably can assume, and also that of the application and signal. Since the signal is WWVB in this case, we can ignore that factor. Also, you don't want to be completely de-tuned from start either. I'm sure John knows this already.
> 
> Cheers,
> Magnus
> 
> On 04/01/2013 01:05 AM, Bob Camp wrote:
>> Hi
>> 
>> If the VCXO's tuning voltage runs from zero to 5 volts, and the VCXO tunes 0.1 Hz / 0.5 volts at 12 MHz, then it has a total range of about 1 Hz at 12 MHz. That's about 0.08 ppm of tune range. A generic crystal likely has a tempo of 0.1 to 1 ppm / C. My guess is that you will need a bit more tuning range on the VCXO to keep things locked long term. Putting your tuning cap in series with the varicap should help this a bit. You may also need to add a coil in series with the crystal.
>> 
>> Bob
>> 
>> On Mar 31, 2013, at 6:30 PM, paul swed<paulswedb at gmail.com>  wrote:
>> 
>>> Thanks John.
>>> 
>>> 
>>> On Sun, Mar 31, 2013 at 5:21 PM, John Ackermann<jra at febo.com>  wrote:
>>> 
>>>> At Paul's request, I've put his document about the PSK scrubber for WWVB
>>>> at:
>>>> 
>>>> http://www.febo.com/pages/**wwvb_psk/WWVB%20d-psk-r%**2003302013.pdf<http://www.febo.com/pages/wwvb_psk/WWVB%20d-psk-r%2003302013.pdf>
>>>> 
>>>> John
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