Re: ATM Global Positioning System

["Jack Brindle" <jackb@ricochet.net>]

>Is it conceivable that using two receivers in this mode (is the
"differential"
>GPS), one on each end of the scope, that you could know exactly which
direction
>it is pointing (like built-in, never-need-orienting setting circles)?
>
>Stuart Field
>
>Dave Rowe wrote:
>
>>
>> I design and build these [GPS] systems for a living...
>
>>  ...I may even use two receivers, separated by a few meters, to
>> find true North to very high accuracy using multi-signal carrier-based
>> interferemetry.
>

Nice try, but differential GPS doesn't work this way. The second receiver
is
a benchmark receiver with very accurately know position. The two GPS units
then communicate to exchange information which allows the "first" one to
determine its position very precisely. The precision of that calculation is
very much dependent on the accuracy of the second receiver's positioning.
Simply adding a second receiver a few meters away just won't do it.

-JackB
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"My name is bud lightbeer. I come in pieces!"