# [time-nuts] True to there word. - Fancy WWVB

Bob Camp lists at cq.nu
Tue Feb 9 01:40:15 UTC 2010

```Hi

Yes indeed, you need to be sure you don't get a cycle slip. That's not trivial when the signal goes to zero while moving phase.

There I think you need to depend on something like a reasonable OCXO and a long time constant loop. That brings in other problems. I assume that you are going to have to train your loop to "expect" the ID shifts and time markers. Again, they are predictable. It's just software ....

More or less:

Take all of the things you can compute about the signal and feed them in. Lock the "computed" signal against the received signal. Way less complex than what they do with GPS. Since it's all *very* slow, a beater PC can easily keep up with all the adjustment math.

Bob

On Feb 8, 2010, at 8:28 PM, J. Forster wrote:

> If you track for a day, and draw a straight line throught the diurnal
> shift, you can easily see a frequency drift of 45 degrees. That's 1/8
> cycle of 60 KHz or about 2 uS. So 2x 10 E-6 out of 10 E5, so you can see 2
> x 10 E-11 in a day.
>
> ASSUMING the lock does not break.
>
> -John
>
> ===================
>
>
>
>> Hi
>>
>> People rarely want to use WWVB mobile. The location of the transmitter and
>> receiver can be looked up on a map. The time of sunrise at both locations
>> should be something that could be calculated.
>>
>> Assuming you are willing to put up with all of that, you should be able to
>> do a first order correction on the shifts. The question obviously is -
>> just how good would the net result be? Is it a 5:1 sort of thing or do you
>> get a couple of orders of magnitude?
>>
>> Bob
>>
>> On Feb 8, 2010, at 6:40 PM, J. Forster wrote:
>>
>>> Yes, but WWVB is a PITA to use (because of the diurnal shifts) compared
>>> to
>>> LORAN.
>>>
>>> -John
>>>
>>> ===============
>>>
>>>
>>>> Hi
>>>>
>>>> WWVB is pretty safe. When they do a cost/benefit thing on these
>>>> services,
>>>> they take a look at how many taxpayers are using the service as
>>>> intended.
>>>> The "mission" of WWWVB is to put out time signals. There are a *lot* of
>>>> taxpayers with WWVB "atomic clocks" on their walls.
>>>>
>>>> Bob
>>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>>> Behalf Of Don Henderickx
>>>> Sent: Monday, February 08, 2010 4:07 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: [time-nuts] True to there word.
>>>>
>>>> The lights went out (actually red) on my Austron 2100 r this morning.
>>>> (whats  next WWVB ?)
>>>> Don H
>>>>
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>>>
>>>
>>>
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>
>
>
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