[time-nuts] GPS antenna length correction

Chris Albertson albertson.chris at gmail.com
Tue Apr 29 00:00:05 UTC 2014

On Mon, Apr 28, 2014 at 3:53 PM, Bill Beam <wbeam at gci.net> wrote:
> As mentioned earlier the position of the receiver is indeterminate unless
> the vector displacement from the antenna to the receiver is accounted for.
> Accounting for the cable delay will only correct the absolute time.
> Imagine a 100m antenna feed line; the receiver could be anywhere within
> 100m of the antenna (even above it or at it).  The algorithm that computes
> position
> needs to know this.

Yes, of course.  The GPS receiver reports the location of the antenna.  If
you need to know some other location you have to apply some (x,y,z) offset
from the antenna.   Actually I doubt anyone would care about the location
of the receiver.   They might want to know the location of the vehicle's
center of mass or the location of some display screen.    The cable delay
accounts only for the offset in time.

Time and location really are different things, especially because a cable
can take a non-straightline path or even be coiled up.


Chris Albertson
Redondo Beach, California

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