[Milsurplus] APS-13 Questions

[J Forster]

The APS-13 is a pretty famous set, but there seems to be little
information on it around. Most google hits are about computer gaming.
Does anyone know:

Is there a control box for it? If so, what is the number? The info on
MilList is unreadable.

It's a pulsed radar. Does it basically look for a returned pulse within
a predetermined time (range) window? It does not appear that the time
window is operator adjustable.

What did the antenna look like?

Thanks,
-John