[time-nuts] position determination over short distance

[WarrenS]

James


Question
So if the antenna is rotated in any and all of its axes, it does not should like from what you are saying there is really just a single point in it like you get for say 'center of mass'. that stays at a known spot.
It sounds  more like a bunch of calibration points than a single point, similar to a calculated lookup table, depending on angle etc. 
Does the question make any since?
In any case do you think it would help in the original question, which was to measure NON GPS RF signal distances to mm distances??

Thanks,
Warren 

*********************

On 12/5/08 8:55 PM, "WarrenS" <warrensjmail-one at yahoo.com> wrote:

>
>
> To  Björn
> wow,  neat, mm accurate antennas,
> That means the RF way still has some hope.
> How does it get the information down the cable without unacceptable loss of
> accuracy?
> Anyone know how they make these antennas, and can it be done with small cheapy
> ones?
>

Nothing really special. Mostly, it's care in the surroundings.. A series of
choke rings to suppress multipath reflections from under the antenna.
Actually, putting the usual inexpensive hockey puck style antenna on a
cookie sheet makes a fair approximation.

The other thing is that they get calibrated.  You make a series of
observations of the signals from GPS satellites as they move overhead. You
know where the satellite is, and where the antenna is (in a long term
averaging sense), and you can calculate the phase center position as a
function of look angle.

I think the GIPSY software does this for you.

Once you know what a particular design does, then it's more a matter of
construction tolerances.