Radar 5

Question 1

Define Intra-Pulse modulation

Answer 1

Modulation on or within individual pulses.

Question 2

Define Inter-Pulse modulation

Answer 2

The changing or variation of the interval between successive radar pulses.

Question 3

Describe the methods of intra-pulse modulation.

Answer 3

• Amplitude Modulation on Pulse (AMOP),
• Frequency Modulation on Pulse (FMOP), and
• Phase Modulation on Pulse (PMOP).

Question 4

Describe the methods of inter-pulse modulation.

Question 5

Explain the uses of intra and inter-pulse modulation techniques as adopted by modern radar systems.

Question 6

Describe Aplitude Modulation on Pulse (AMOP)

Answer 6

Amplitude Modulation on Pulse (AMOP) is achieved by:
* A modulating waveform causing variations in individual pulse amplitude.
* The modulation may be used to apply a binary number to the transmitted pulse for identification purposes in the receiver.

Question 7

Describe Frequencey Modulation on Pulse (FMOP)

Answer 7

Discrete FMOP is a method of coding pulses.
* Requires the modulating waveform to step through discrete frequencies.
* Can be used for pulse compression.
* Can be used for pulse encoding.

Question 8

Describe Phase Modulation on Pulse (PMOP)

Answer 8

Phase Modulation on Pulse (PMOP) is caused by the carrier phase angle departing from its reference value due to a modulating signal.
* There are three basic types of PMOP:
* Quadrature (90° Phase Shift)
* Binary Phase (180° Phase Shift)
* Polyphase (0, 120 and 240° Phase Shifts)

Question 9

Describe Unitentional Modulation on Pulse (UMOP)

Answer 9

A fourth intra-pulse modulation effect can occur unintentionally. UMOP is caused by modulation sensitivity problems in high power transmit tubes.
Common causes of UMOP are:
* Temperature
* Equipment Aging
* Poor Maintenance