[time-nuts] Position accuracy and Thunderbolt performance

[Mark Sims]

Ahhh,  that's the 64 nanosecond question.   I did a lot of self surveys with a geodetic grade antenna over a spot known to within less than a millimeter.   Most results were with 6 feet lat/lon  6 meters altitude (hey, can I get a job at JPL landing spacecraft?  I can mix english and metric in the same measurement).

But,  the key word is most.  Some were off over 50 feet lat/lon and 100 meters altitude.  Unless you have a known position to compare against you may never know for sure.  And,  if you have a precisely known location,  you can't enter it into the Tbolt with sufficient accuracy since that message uses single precision numbers.

I am doing a couple more tests with a 50 foot error and another with all the error in the altitude (those first two graphs were with lat and lon offset by around 141.4 feet and the altitude exact)

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Or. to put it another way, what could we reasonably  expect to see as a position error if the T'bolt is  allowed to self survey?
 
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