[time-nuts] Precise Time transfer and relative position over ashort baseline

[Attila Kinali]

On Mon, 11 Apr 2016 19:58:33 +0200
Attila Kinali <attila at kinali.ch> wrote:

> The baseline is not the problem in this case, but the delay within
> the GPS receivers and the cables. To keep their variation below 1ns
> is already quite a challenge. The usual method for this is to have
> the whole GPS receiver setup temperature stabilized, then feed the
> reference point with a low phase-drift cable. After installation of
> all sites, use a special traveling GPS reveiver as a calibration
> standard between the sites. The BIPM uses something like this and
> achieves <200ps over a calibration period of 3 weeks for the traveling
> GPS receiver.


While we are at it: SP did some measurement of temp coefficent for GPS
receivers in [1]

Then there was a study at NIST that looked at the influences of the
rooftop environment on timing accuracy in [2].


[1] "Thermal influence on the receiver chain of gps carrier phase equipment
for tie and frequency transfer", by Rieck, Jarlemark, Jaldehag, Johansson,
ETFT 2003 (again, can be found on eftf.org)


[2] "Effects of the rooftop environment on gps time transfer",
by Lombardy and Novik, 38th PTTI, 2007



			Attila Kinali

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