[time-nuts] Impact of GPS antenna height measurments

[Gary E. Miller]

Yo Mark!

On Sun, 26 Jun 2016 09:02:55 -0400
Mark Barettella via time-nuts <time-nuts at febo.com> wrote:

> I
> estimate my antenna’s actual height at about +5 m high and the gps
> indicates -17 m.

Others have covered some obvious details.  Different ellipsoids,
long term surveying, etc.

> My question is will this adversely influence the
> accuracy of the gpsdo output?

Depends on how accurate you need.  I'll assume your estimate is perfect,
which is that your GPS is reading off by 22 meters.

The speed of light is  299,792 kilometers/second.

So to travel 22 meters is about .000,000,073 Seconds.  Or 73 nanoSecond.

All else being equal, does a constant 73 nanoSec matter to you?

For comparision, a Trimble RES SMT 360 only promises 15 nanoSec (1 sigma).

If all you want is a stable frequency from your gpsdo then the offset
is not relevant.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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