Radar | Secondary Surveillance Radar Flashcards
This improves on primary radar by using __-pulse secondary equipment to provide more information
double
An interrogation ground station send a rotating beam of ___ modulated signals in all directions in a form that is recognised as a request for information
pulse
A transponder is carried that receives interrogation pulses at ____ _Hz, superimposes information onto it, and sends it back on another paired frequency of ___ _Hz
1030 Mhz, 1090 MHz
The interrogation and response pulses are ___ _Hz apart
60 Mhz
Primary radar is ___ accurate in terms of bearing and distance
more
Enhanced surveillance extracts additional information from the aircraft, known as ___
Downlink Additional Parameters - DAP
Mode 3/A asks ____
who are you?
Mode C asks ___
how high are you?
Interrogations are sent as a pair of pulses and a ___ pulse
control
The decoding time between the ___ pulses determines the operating mode of the transponder
interrogation
A spacing for transmission and reception is called a ___
mode
For modes 3/A, and C, a pair of pulses called __ and __ are sent to the aircraft
P1 P3
Mode A has a ___ interval between pulses, whilst mode C has a ___ interval between them
shorter, longer
An omnidirectional antenna sends out P2, which is ___ than the others, but stronger than any sidelobes.
weaker
If the transponder can receive ___ ___ ___, it knows it’s receiving the main lobe, but it it sees __ then it knows it’s receiving a side lobe, with responses being avoided.
P1 and P3, P2
Mode S uses a short __ pulse
P4
A long P4 pulse means that the interrogator is transmitting a ___ ___ ___.
Mode A/C/S all call
A special position ident pulse is sent by using the ___ switch
IDENT
When answering an interrogation, Mode A transponders will transmit up to __ pulses, _ microseconds apart (__ for Mode B), with the first and last being frame pulses (__ and __) which enclose the whole signal so it doesn’t get muddled with others. The remaining __ can be there or not, in up to ___ combinations.
14 8 17 F1 F2 12 4096
The IDENT pulse is transmitted for up to __ seconds
20
Each number selection knob controls _ pulses; _ _ _ _
3, A, B, C, D
Selecting 2300 would produce the codes ___
010
110
000
000
0 means ___ signal, selecting 2, generating a pulse 010, means that only pulse _ of the pulse group is transmitted.
no, 2
Mode C is just Mode _ plus altitude reporting
A
Mode C sends flight level information from the aircraft in ___ft increments
100
ATC’s presentation gives information regarding your flight level that’s accurate to within __ft, with the tolerance being __ft
50 300
Mode C pulses are __ microseconds apart
21
The S in Mode S stands for ___
selective
Mode S pulses are __ microseconds apart
25
Mode S gives each aircraft a unique code, allowing it to only respond to requests directed to them, as opposed to ___ requests.
all
Mode S provides altitude reporting in __ft intervals
25
With Mode S, the initial two pulses are followed by a ___ pulse containing a string of up to ___ bits.
long 112
The first __ bits of the 112 bit string are a unique address to the aircraft
24
Mode A/C/S all calls consists of 3 pulses __, __, __
P1 P3 long P4
A control pulse __ is transmitted following __ to suppress responses from aircraft in the side lobes of interrogation antenna
P2, P1
A Mode A/C only all call consists of 3 pulses __, __, __
P1 P3 short P4
A Mode S transponder regularly delivers a squitter, which is a short transmission of basic data without a ___ ___, only to advertise the position
receiving request
Mode S can provide a 2 way data link on ___ and ___ _Hz, used by TCAS
1030 1090 MHz
Mode S equipped aircraft over ___kg or with max TAS over ___kts must use transponder antenna diversity
5700 250
The two main functions of a Mode S transponder are __
- G/A and A/G data link
- Improved ATC aircraft surveillance capability
Level 1 provides __ data link, but recognises individual addresses. It is Mode _ with SELCAL.
no C
Level 2 provides standard data link communications in ___ direction(s)
both
Level 3, 4, 5 increase the data link capabilites beyond the ___ ____ ___.
standard flight information
Modes _ and _ can suffer from interference, known as fruiting and garbling
A C
FRUIT stands for ___
False Replies and Unsynchronised to Interrogator Transmissions
SSR equipment uses the ___ frequencies for transmitting and receiving, any interrogator can trigger any transponder within range, so any ground station can receive their replies, which appear as interference/fruit
same
Garbling comes from other aircraft within ___ ___ ___ ___ responding to the same interrogation
line of sight range
The length of the transponder code train is about __ microseconds, resulting in it not always being possible to decipher replies from aircraft within _ to _ miles of each other
2 3
You could get overlapping returns within . miles
1.7
___ in the decoder equipment cancel garbled replies
Circuits
Mode S interrogator and receiver operate on the same frequency as the ___ ___
standard SSR
A Mode S ALL CALL will be responded to by Modes ___
A C and S
A Mode S transponder will respond to a Mode S ALL CALL by sending ___
- Aircraft ID
- Capability of all equipment on board
Elementary surveillance will downlink:
- Callsign
- Altitude
- Transponder capabilities
- Status
Enhanced surveillance will downlink:
- Mag heading
- IAS
- TAS
- MN
- Vertical Rate
- Roll angle
- Track angle rate
- True track angle
- Ground speed
- Selected altitude
