Chapter 1 - Radar Fundamentals Flashcards
What form might the transmitted energy be in primary radar?
- CW
- Pulses
- Frequency modulated continuous wave
How does a secondary radar detect targets?
By means of a stimulate/response system
What are all secondary radar systems?
Pulse systems
What is the frequency range of airborne radar equipment and what is this known as?
1 GHz to 15 GHz
Centrimetric radar
In order to detect targets, and discern their range, bearing and height, what components do pulse-modulated radar units require?
- Transmitter
- Aerial system
- Sensitive receiver
- Indicator
What is pulse width (TD)?
Period that a transmitter is switched on
What is pulse recurrence period (PRP)?
Interval between the leading edges of the pulses
What is the pulse repetition frequency (PRF)?
Number of pulses occurring in one second
What does the transmitter generally consist of?
- Master timing unit
- Modulator
- Transmitter oscillator
Where are the master timing unit outputs fed to?
- Modulator to trigger the transmitter
- Indicator to synchronise the time base
What does the master timing unit do?
Produces timing pulses which recur at precise and regular time intervals and determines the PRF of the equipment
What is the purpose of the modulator?
Electronic high powered switch triggered by pulses from the master timing unit
Switches the transmitter oscillator off and on
What turns the transmitter oscillator on and off?
On - leading edge of the modulator output pulse
Off - trailing edge of the modulator output pulse
What is the minimum number of cycles which must be included in each pulse?
200
What is the relationship between average power, maximum power, PRF, and TD?
PA=PmTDPRF
What frequencies do centrimetric radar equipments operate at?
3 GHz to 30 GHz
What are the two aerial arrangements commonly used in airborne radar equipments?
- Parabolic reflector
- Flat plate antenna
How is bearing information derived in airborne radar?
Scanning the aerial using a scanning motor
What kind of remote position indicator might be used in a system which would indicate azimuth and tilt angle of the aerial during scanning?
Synchro system