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RADIO NAV — CH.12

Ground RadarRadio Navigation — DGCA CPL practice questions

Question 1 of 4

A primary radar has a PRF of 275 pps. Time interval between leading edges of successive pulses:

A.3.64 milliseconds
B.36.4 milliseconds
C.3.64 microseconds
D.36.4 microseconds

All 4 questions — Ground Radar

Radio Navigation · DGCA CPL. The correct option is marked on each.

  1. Q1. A primary radar has a PRF of 275 pps. Time interval between leading edges of successive pulses:

    • A.3.64 milliseconds✓
    • B.36.4 milliseconds
    • C.3.64 microseconds
    • D.36.4 microseconds

    Why: PRI = 1/275 s = 1,000,000/275 µs = 3636 µs = 3.64 milliseconds .

  2. Q2. Primary radar PRF = 450 pps. Maximum range (ignoring PW and flyback):

    • A.333 NM
    • B.180 NM✓
    • C.666 NM
    • D.360 NM

    Why: Max range = 81,000/450 = 180 NM .

  3. Q3. Frequency band and scan rate of Airfield Surface Movement radars:

    • A.SHF; 60 rpm✓
    • B.SHF; 200 rpm
    • C.EHF; 100 rpm
    • D.EHF; 10 rpm

    Why: ASMI operates in the SHF band (15–17 GHz) at a scan rate of 60 rpm .

  4. Q4. Radar with scanner rotation 60 rpm, beamwidth ~0.5°, PRF 10,000 pps. This is:

    • A.ASMI with theoretical range 8 NM✓
    • B.Precision Approach Radar
    • C.ASMI with theoretical range 16 NM
    • D.High resolution Surveillance Approach Radar

    Why: All characteristics (60 rpm, narrow beam, high PRF, short PW) match an ASMI . Max range = 81,000/10,000 = 8.1 NM ≈ 8 NM .