EQT 4 SSR Flashcards
What is SSR
A system of RADAR using ground interrogators and airborne transponders to determine the position of aircraft in range and azimuth.
What frequency does the interrogator transmit on?
1030mhz
What frequency does the interrogator receive on
1090mhz
Why do the frequencies for TX and RX have to be different
To stop self interrogation
What length wavelength is used for SSR
30cm
UHF/SHF
What is Mode A used for
Identification (squawk)
What is Mode C used for
Vertical position (height)
How does an a/c transponder know which type of interrogation
The different timings between pulses
What code do transponders use to respond
Binary
How long between mode A pulses
8.5 micro seconds
How long between mode C pulses
21 micro seconds
How many info pulses are in a Mode A reply?
12 info pulses
4 numbers for squawk (only 0-7 possible due binary)
How many possible squawks are there
4096
What are the 3 types of codes
Discrete
Non discrete
Special codes
What are the special codes
7500
7600
7700
What does ORCAM stand for
And who is in charge of it
Originating region code assignment method
Eurocontrol
How many participating areas is ORCAM divided into
5
What are the benefits of an ORCAM squawk
Reduces RTF and cockpit workload
Squawk can be retained take off until touch down
How many blocks of codes to ACCs have and what are they
2
Internal and international
Mode C reply
How many bits?
What does it give?
Give height read out
Uses 11 bits
3 number for height, 8&9 required so 11 bits to fit binary numbers in
What is the max uplink capacity
23 bits
11 Mode C
12 Mode A
What is Garbling
False codes display of A/C are so close together their responses to Mode A interrogation overlap
What do you use to overcome garbling
Degarbler
What is FRUIT
False response un-synchronised in time
Replies that have not been triggered by the interrogator
How do you remove fruit
With a defruiter
What is mono pulse SSR and why use it
Single pulse used. Average measurements made on several or all of the pulses received.
Improves accuracy
Fruiting and garbling minimised
