Description of the radar set, tactical-technical characteristics
Figure 1: Antenna type ASS of Type 242 interrogator
|frequency:||165 … 185 MHz||159 … 189 MHz|
|pulse repetition time (PRT):|
|pulse repetition frequency (PRF):||125 or 50 Hz||up to 500 Hz|
|pulsewidth (τ):||6 µs||4 µs|
|peak power:||1 kW||2 or 10 kW|
|hits per scan:|
Type 242 is an operating on a fixed frequency in VHF-Band interrogator in the standard Mark Ⅲ IFF system.
The Type 242 is used in conjunction with the radar Type 275 and Type 291. Type 242M is used in conjunction with the radar Type 277 series and Type 293. Type 242P/Q is normally used with Types 960/982 and the height-finder Type 983.
The PRF of the main radar equipment is counted down (4:1 or 10:1) in the modulator which fires the interrogator transmitter and also a trace displaced from the radar trace on the A-scope. The interrogator signals are received by the responser unit and displayed on this trace as inverted signals along with the normal echoes. Coincidence of the interrogator pulse and the radar echo identifies the target.
The associated shipborne transponder is Type 253 series or Mark Ⅲ IFF when fitted in aircraft.