Book 4 Flashcards
Fixed frequency
Pulsed radar system transmits at same frequency
Frequency Agile
The transmitted frequency for each pulse is different
Disadvantages of fixed frequency radars
Clutter
Interference
Second time around echoes
Advantages of frequency agile radars
Clutter reduced
Low chance of interference
2nd time echoes will come back weak and can be differentiated
Better detection range
FAR Techniques
Spin-disc magnetron
Frequency agile master oscillator power amplifier
FAR Block diagram components
Monopulse radar (Angle tracking)
Continuous tracking of a targets AX and EL in either ground mapping or AI radar
Monopulse Resolution improvement
To obtain accurate AZ, EL and range information to a target using a single pulse
The pilot selects track while scan describe the scanning pattern and the type of beam that would be produced
1,2 or 4 bar scan
Pencil beam
Explain track while scan principles
Disadvantage of TWS
Updated once every scan and not continuously
List radar systems that use Monopulse techniques
Terrain following
Ground mapping
Airborne interception
Describe target tracking quadrant principle
The single beam is sent out on four separate beams. When the target is in the centre the quadrant echoes are similar in strength
How does two beam Monopulse radar when a target is in the centre of the two beams
The amplitude of the target echoes is the same in both beams
Information obtained from Monopulse ranging
Slant range
Depression angle
Explain principles of moving target indication
Identifies moving target
Uses Doppler effect
Can suffer from blind speeds
Explain principles of pulse compression
Wide pulses are transmitted to give more energy for long range
Processed as narrow pulses
Good target discrimination
Effects minimum range
List the advantages of using the pulse compression technique in primary pulsed radar
Some resistance to ECM jamming
Better target discrimination
Longer-range
Improved S/N ratio
The pilot has said when they selected chirp they lost the target a target at 3KMs
The increase in pulse size will effect the minimum range
Explain how the basic pulse compression technique could be improved
If more frequencies were used this would result in a narrower pulse with a higher amplitude
Pulse Doppler radar
To detect air and ground targets using Doppler effect
Can detect targets at range and against ground clutter and track multiple targets
Modern radar able to operate in a number of modes with airborne computer
Advantages of pulse Doppler radar
Can discriminate targets against ground clutter
Allow early detection of targets at range
Uses a single aerial for TX and TX
Block diagram purposes
