[time-nuts] Lady Heather survey accuracy

Jim Lux jimlux at earthlink.net
Thu Jan 24 23:07:42 EST 2013


On 1/24/13 8:13 AM, John Nelson wrote:
> I hesitate to ask this question on here since it's perhaps more one for
> position-nuts rather than time-nuts. My excuse is that it involves a
> Thunderbolt ;-)
>
> I've been a happy user of a Thunderbolt for a while as an accurate time and
> frequency source but until recently I hadn't got round to mounting it in a
> proper enclosure with its PSU and finding a permanent home for the result in
> the office. Having done so I asked Lady Heather to carry out a 48h
> 'precision survey' and got a result which although close to that done when I
> first acquired the unit was about 10m different. I then carried out two
> further surveys which gave similar disparate results.
>

Can a thunderbolt and LH report observables in RINEX format?   If so, 
you can submit it to the GDGPS site at JPL and get very accurate post 
processed positions.

http://apps.gdgps.net/

The following observation types are defined in RINEX Version 2.10:  | 
L1, L2: Phase measurements on L1 and L2
C1    : Pseudorange using C/A-Code on L1
P1, P2: Pseudorange using P-Code on L1,L2
D1, D2: Doppler frequency on L1 and L2
T1, T2: Transit Integrated Doppler on 150 (T1) and 400 MHz (T2)
  S1, S2: Raw signal strengths or SNR values as given by the receiver 
for the L1,L2 phase observations

you might also be able to use GIPSY software yourself..
https://gipsy-oasis.jpl.nasa.gov/

and ingest the precise stuff from the global differential gps system..

for post processed clock data and precise ephemerides for the satellites 
( if you want the ultimate in timing info, albeit post processed).. 
You'd record your time stamps/time intervals from your 1pps, etc.  and 
then later adjust them.

https://gipsy-oasis.jpl.nasa.gov/index.php?page=data


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