[time-nuts] Ashtech 3DF GPS

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

Thanks,
Stan