[time-nuts] Common-View GPS Network

[Magnus Danielson]

On 04/16/2013 05:23 AM, Tom Van Baak wrote:
> I too would be interested. The topic of common view GPS comes up every now and then. The incentive to use common view time transfer (CVTT) is reduced when plain old time transfer (TT) is so good already. Still, it's worth a try.
>
> I'd be curious what level of improvement is possible. It will depend on the receiver and the antenna. I believe the NIST project uses fancy antennas but normal M12 receivers.

They use the Novatel 700 pin-wheel antenna.

> So there's hope for the amateur. I don't think the TIC is that important: the sawtooth granularity is 1 ns so precision greater than that is wasted. One averages over many minutes anyway.
>
> Simulations would be a great idea. If you need raw data let me know.
>
> Google for CGGTTS and RINEX. Not all GPS receivers provide the level of per-satellite information required for common view. I know the M12 does, as well as high-end specialty timing receivers. I don't know if the Trimble TBolt or Res-t give out enough information to generate RINEX. But you can get the individual SV contribution to the solution using TBolt packet 0x8F-A7.

Setting up my M12M-T for this would be fun. That should be attainable 
for most folks around here.

I wonder if one should only measure the PPS thought. Looking directly at 
the clock could help to separate the clock drift and the time, even if 
you get sufficient clues from the PPS and sawtooth correction.

Cheers,
Magnus