www.radartutorial.eu Radar Basics

Dwell Time and Hits per Scan

Most processes in pulsed radar are time dependent. Thus, some terms have been established to describe this time-dependence.

Figure 1: the target on the screen is a result of hits

Figure 1: the target on the screen is a result of hits

Figure 1: the target on the screen is a result of hits

Dwell Time

The time that an antenna beam spends on a target is called dwell time TD. The dwell time of a 2D–search radar depends predominantly on

The dwell time can be calculated using the following equation:

TD = ΘAZ · 60 ; in [seconds] (1)

360° · n

Hits per Scan

The value of hits per scan m says how many echo signals per single target during every antenna swing are received. The hit number stands e.g. for a search radar with a rotating antenna for the number of the received echo pulses of a single target per antenna turn. The dwell time TD and the pulse repetition time PRT determine the value of hits per scan.

m = TD = ΘAZ · 60 (2)


PRT 360° · n · PRT

So that radar equipment can evaluate the target informations with sufficient precision, hit numbers are between 1 and 20 as necessary, which depends on the radar set operating mode.