prm

Going into High PRF. (Not PRM)

PRF is Pulse Repetition Frequency. One of several Parameters of a radar signal that we monitor to not only ID the type of radar, but also determine is function and mode of operation.

It is the number of times the radar signal itself turns on and off per second. the radar cannot normally listen and transmit at the same time so it rapidly switches on and off like a strobe from anywhere from a few hundred to thousands of times per second. With intervals between each pulse measured in milliseconds (PRI... Pulse Repetition Interval)
The Duration of each individual pulse being known as the PW or Pulse Width.
Along with carrier frequency, Scan rate and type... these are used to determine what a radar is and what it's doing.

In particular to PRF... a Higher PRF gives the radar a much greater accuracy and discrimination in accurately tracking a specific target, but limits the radar's maximum range in searching for targets.

A SAM site will generally have two radars, a Search radar and a target tracking/missile guidance radar. Some modern systems combine it all into one radar that can switch into different modes.

The Search radar will search for and find targets well outside the engagement zone of the associated missile. As the target gets closer the target's data is handed off to the tracking and guidance radar. The tracking radar first has to acquire the target for itself, even though the search radar tells it where to look, it still has to find it.
It will do this and then track the target in a lower medium Hertz PRF.

Once the target is engaged the radar will jump into a much higher PRF in order to accurately guide the missile into the target. This is how you can tell if the Missile system's radar has change from tracking to guiding a missile, meaning they've fired on you and the missile is guiding.

Me?
US Navy EW (Electronic Warfare) SLQ-32 Operator.
I intercepted and if needed, jammed enemy radars and radar guided weapons for a living.




I joined the Navy to see the world, only to discover the world is 2/3 water!