[time-nuts] Time Transfer

[Brooke Clarke]

Hi Didier:

Been surfing your Timing web page and came across
http://www.ko4bb.com/Timing/FrequencyReference.html
Got there by working up the URL for the Vig paper.

An ordered list of Time Transfer methods from carrier phase GPS to the 
Astrolabe is at:  http://www.prc68.com/I/timefreq.shtml#TT
that ranks HF time stations far below other methods, so although they can be 
used there may be better choices that are affordable.

Also for GPS timing applications (i.e. the GPS receiver is in position hold 
mode) a single satellite is all that's needed.  Adding more satellites can add 
a failure alarm function but may not improve accuracy.  In my case multipath is 
a big problem so a high elevation mask is needed.

The problem with a less than 12 channel receiver relates to how satellites are 
selected.  The Motorola timing receivers will continue to track a satellite 
until it sets rather than switch to a a new one which may be directly overhead. 
  The "use highest in the sky" applies to how a new satellite is selected. 
Once selected the satellite is tracked until it sets.

An idea: When averaging GPS 1 PPS signals the receiver switches satellites as 
the currently tracked ones set so there may be a slight change in accuracy 
because of the satellites being used.  But changing from a satellite that's 
about to set i.e. that has a lot of multipath to high in the sky sat should 
make for a better 1 PPS.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam