[time-nuts] FTS4060 C Field Time Constant

Brooke Clarke brooke at pacific.net
Tue Mar 1 12:27:41 EST 2005


Hi Brian:

I've been thinking about bringing my laptop to the FTS4060 and running 
TAC32 and watching to see if there's a correlation between the time 
interval changes and a change in which satellites are being tracked.  
But even with the jumps if there is no drift then I know the C field is 
properly set, it's just going to take longer.  Also the LORAN-C is 
looking better and better as a precision time transfer method.  It's 
been 5 days since Middletown came back on the air and the 2100T Timing 
receiver was restarted and the offset is only 20 nano seconds.  
20E-9/(5*86400) = 4.6E-14.

Have Fun,

Brooke

Brian Kirby wrote:

> Its possible, its multipath.  Depending on your receiver, you can shut 
> off reception from individual GPS PRNs.  Check to see which ones are 
> in use at the time, and then turn one off.  12 Hours later, turn it 
> back on and turn off another, etc.
>
> Also, if you can turn off GPS PRNs, you can pick at time common with 
> NIST and use the GPS archive at 
> http://www.boulder.nist.gov/timefreq/service/gpstrace.htm to compare 
> time (use view track to see one satellite by itself).
>
>
> Poul-Henning Kamp wrote:
>
>> In message <4223C82C.4030108 at pacific.net>, Brooke Clarke writes:
>>
>>  
>>
>>> Another clue that it's GPS based is to notice that the time of day
>>> when the big changes occur are about the same.  The major lines are
>>> each at midnight.  Maybe it's related to which GPS satellites are
>>> being used?
>>>   
>>
>>
>> Have you tried setting a mask-angle in your GPS ?
>>
>> Try 10 or 15 degree depending on how cluttered your horizon is.
>>
>>  
>>
>
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