[time-nuts] Ashtech 3DF GPS

[bg at lysator.liu.se]

Hi Stan,


> On more or less of a whim, I found and bought an Ashtech 3DF GPS. The
> interesting thing about this particular GPS is that it uses four separate
> GPS antennas mounted in a diamond pattern about 1 meter on a side and can
> compute not only the "usual" stuff, but also heading, roll, and pitch
> angles. I had heard of this being possible, but never actually seen it
> done.
> There are no accessories included with this unit, other than the power
> cord.
>
> Does anyone know where I can find a manual for it?

Look for manuals in

    ftp://ftp.ashtech.com/OEM,%20Sensor%20&%20ADU/

perhaps it is this one? Or an earlier version.
   ftp://ftp.ashtech.com/OEM,%20Sensor%20&%20ADU/ADU2/Reference%20Material/adu2.pdf


> Will this GPS work with just four ordinary active antennas or are the
> antennas special?

Will probably work with almost any antenna, but for good performance use a
geodetic quality rover antenna.

> Given the complexity of the additional data massaging it does to extract
> the
> angular data, does this also mean that it will have more accurate position
> and or timing performance?

No, its specialty is to determine the relative positions of the four
antennas. This will give heading, roll and pitch of the vehicle the system
is mounted on.

> Does it need all four antennas to be able to do anything at all, or can it
> compute position and time with just one antenna connected?

It will probably do position and time with just the "master" antenna
connected.

> Thanks,
> Stan

Good luck!

--

    Björn