[time-nuts] multipath on GPS

[Hal Murray]

jimlux at earthlink.net said:
> Does anyone have a feel for what the minimum size reflector at some small
> distance would be detectable on a GPS timing receiver? WOuld you be able to
> see a change of a 1 meter square reflector 10 meters away? 

I suspect it depends on the elevation angle of the reflector.

My wise-ass answer is something like:
  Please try it and let us know what happens.

A variation on that question is how do I tell which of two antenna positions 
is better?

How would you measure that?  With a good reference clock, would it be enough 
to just collect PPS offsets and then compare adev with/without?  How much 
data would you need?  How much variation is there due to the changing 
satellite patterns?

What would you do if you don't have a good reference?  Do GPS receivers 
provide enough signal quality data?

----------

I have often wondered if the reflections off a nearby 747 would cause 
troubles.  I live roughly 20 miles off the end of the San Francisco airport.  
It's common for planes to fly over my house while they are getting lined up 
for the landing pattern.  Most large planes now broadcast their 
position/speed.  When I get time, I want to capture that data and see if I 
can find any correlation between planes nearby and something like a TBolt 
going into holdover or dips in the signal quality from a satellite.


-- 
These are my opinions.  I hate spam.