Radar Theory Flashcards
What does PRP stand for and what is it?
Pulse Recurrence Period
The time taken to transmit a pulse and the quiet period waiting for the return. Basically the time from the start of one pulse to the next
What does PRF stand for and what is it?
Pulse repetition frequency
The amount of pulses sent every second
Formula to find PRP =
1 / PRF
Formula to find PRF =
1 / PRP
When using the PRP or PRF formula, what must the time be converted into?
Seconds (not microseconds etc)
The further away the target is, the smaller/bigger the PRP, and smaller/bigger the PRF
Why?
Bigger
Smaller
At long range there must be a long enough quiet/listening period to allow the returning beam to reach the aerial so the time between pulses will be greater, and therefore the amoount of pulses per second will be lower
Long range radar scanner rotation must be fairly slow because?
The returning pulses may miss the scanner if it is too fast
A shorter PRP would mean a higher/lower PRF?
Higher
Bearing accuracy is mainly controlled by?
Width of the beam
Minimum radar range in meters formula =
c x pulse length / 2
Radar beam width formula =
70 x wavelength / antenna diameter
What affects the minimum range of a radar and why?
Pulse length because if it is sending the pulse for too long the returning wave could reach the aerial before it has finished transmitting and will not be recorded. Therefore, a short pulse length needs to be used for short range radar
Max radar range formula =
c / 2 x PRF
What size antenna diameter provides the narrowest beam width?
Larger diameter
What produces best range resolution?
Short pulses
Pulse power is quoted as the continuous power of a radar, which is …
pulse power averaged over a complete transmission cycle
En-Route Surveillance radar operates at max ranges of … to … NM
200 - 300
En-Route Surveillance radar operates on … MHz with a wavelength of … and pulse length of … microseconds
600
50cm
4
Terminal Surveillance Radar is medium range up to … to …NM
60 - 80
Terminal Surveillance Radar operates in top end of UHF at … to … MHz with a pulse length of … microseconds
1000 - 1200
3.9
Max error of precision approach radar is +/- … ft in azimuth and +/- … ft in elevation
30
20
