[time-nuts] wwvb gps d-psk-r details

Bob Camp kb8tq at n1k.org
Fri Sep 25 19:57:14 UTC 2015


Hi

Once it’s sync’d with GPS, a normal MCU clock should be able to drive it for a 
few days if you had some sort of initial calibration process. 

Bob

> On Sep 25, 2015, at 9:15 AM, John Ackermann N8UR <jra at febo.com> wrote:
> 
> I may be remembering incorrectly, but I thought that you only need the GPS for initial sync; after that shouldn't the processor be able to maintain the sequence without new GPS input, so long as the timer clock doesn't drift too badly?  From a known starting point, the modulation pattern should be predictable into the future.
> 
> John
> ----
> 
> On 9/24/2015 5:11 PM, Charles Steinmetz wrote:
>> Paul wrote:
>> 
>>> Here is the detailed document on the wwvb d-psk-r.
>> 
>> Interesting solution, and a good study in persistence.
>> Congratulations!  But I thought the main point of having a working WWVB
>> receiver was as a backup if GPS fails (or for use in circumstances where
>> WWVB reception is possible but not GPS reception).  If GPS is working,
>> and you have a GPS rx/GPSDO, what is the point of having a time and/or
>> frequency source that relies on GPS but only has the precision of WWVB?
>> And what good is the predictive de-psk-r when GPS is not working?
>> 
>> [Yes, I get that if one runs a museum it's nice to have working exhibits
>> even if they are simulated, and it's no big deal if the exhibits don't
>> work from time to time.  But the curator's solution doesn't seem to
>> solve the time-nuts' real problem.]
>> 
>> I hasten to add that I don't really care one way or the other about GPS
>> alternatives, particularly alternatives with the relative imprecision of
>> WWVB over time scales shorter than geological.  Personally, I presume
>> that if there is ever a persistent, system-wide GPS failure it will be
>> due to a natural or man-made catastrophe of earthshaking proportions
>> (literally) and there will be many, more urgent concerns than time-nuts'
>> experiments.  But others have expressed concern over having just one
>> time and frequency standard available.  For them, isn't a fully
>> independent solution that does not rely on GPS required?
>> 
>> Again, congratulations on bringing this idea to fruition.
>> 
>> Best regards,
>> 
>> Charles
>> 
>> 
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