You're maybe talking about the AN/PPS-5 GSR ?
I have found a 6000 m detection range for a moving human and up to 10 km for vehicle.
You have also AN/PPS-4,6 or 15 (portable GSR) with a range of 1.5 to 3 km.
FOr the ID i don't know (have never serve on GSR) it's probably the ability to give good informations about movement, speed, heading, size of the spotted thing.
For air detection it's more easy,
- a 800 km/h flying bird is not a bird it's a target
.
- a 800 m/s flying bird is no more a bird it's an incoming shell
.