Week 3 Flashcards
What is SAR?
Synthetic Aperture radar
Coherent airborne side-looking radar which utilises the flight path of the platform to simulate an extremely large antenna or aperture electronically and generates high resolution imagery
What is a Swath?
Aircraft flies at a constant velocity and transmits pulses 90 degrees to the flight line
Each pulse sent out at a different location on the flight line defines one element of a synthetic array
Known as a Swath
What is a strip?
Multiple swaths create a strip
The total array
What is Spot formation?
Using electronic steering to illuminate a designated area for longer than usual.
Spotlight mode - beam is held on a given region so it can be mapped repeatedly
What is an advantage of Spot formation?
Gives better cross range resolution
Reduces radar shadow
What are constraints to SAR?
Requires a lot of processing
Target motion can cause blurring
SAR maps have shadow regions due to mountains etc
Cross range resolution, PRF and velocity of a platform are all related and can’t be selected independently
What is CCD? And for what purposes can it be used?
Coherent Change detection
Collect and compare SAR images from the same geometry collected at two different times
CCD algorithm will detect changes invisible to naked eye
Good for looking for IED placement or BDA
What is ISAR and How does it differ to SAR?
Inverse synthetic Aperture radar
While SAR processing relies on motion of the imaging aircraft to collect radar returns for imaging ISAR are technology relies on target motion
A small Doppler change from a target movement in ISAR mode is equal to a large array movement in SAR mode
What are the worst types of clutter for MTI?
Bird flocks
Wave and swell action
Rain in windy conditions
Trees in windy conditions
What is GMTI?
Ground MTI
Can detect, locate and track moving vehicles (and low flying AC)
Name some SAR platforms
P8
Sentinel
Reaper
What should a TDL (tactical data link) provide to give a tactical advantage?
Speed
Security
Accuracy
Clear, unambiguous and easily assimilated information
What is the definition of a digital data link
An automatic means of passing data in an agreed format and speed over a common medium
Definition of tactical data link?
A digital data link carries sufficient data close enough to real time to be useful in a tactical situation
20 seconds or less
What will a TDL report?
Tracks (Hostile, friendly and unknown)
Position
Speed
Heading
Altitude
Tactical orders
What is commonality?
For forces to operate TDL they must have certain common attributes
Same frequency
Same format
Same parameters
Realtime
What is the basic TDL architecture?
Sensor
Data handling and display system
Cryptographic system
Comms system (transmitter/reciever)
What are the three fundamental types of TDL system?
Point to point
Broadcast
Netted
What is point to point system?
Simplex
Duplex
Semi duplex
What is a broadcast system?
Designed to transfer surveillance information from units capable of processing tactical data information to those not.
Simplex
What is a netted system?
For exchanging digital information among airborne,
Land based and ship borne tactical data systems
Duplex
What are the three TDL modes of operation?
Simplex -one way
Duplex - two way simultaneously
Semi- duplex - two way one at a time
What are STANAGS?
Standardized NATO agreements
Technical specifications of TDLs and procedures for their operations
5511 for link 11
5516 for link 16
Current platforms with TDL?
RJ
P8
E3D sentry
Brevity codeword for link 11
Alligator
Brevity codeword for link 16
Timber
Brevity codeword for link 22
Elfin
What type of system is Link 11?
Semi duplex
Netted
What frequencies does link 11 use?
UHF (line of sight)
HF (beyond LOS)
What is the configuration of Link 11?
Tactical data system computer Encryption Data terminal set Radio Coupler Antenna
What does the Tactical Data system computer and encryption do?
Tactical Data system computer collects information and converts it into specific message format (M series for link 11)
Hold in buffer before passing one word at a time to encrypt it
What does the data terminal set do?
Takes the digital encrypted data and converts it to analogue
What does the radio and coupler do?
Modulates a radio frequency carrier
Sent through the coupler to antenna
What are the concepts of operation of link 11?
Requires network control station (NCS) and participating units (PU)
A data link reference point is established (fixed point where positional information is derived)
Network control station calls all participating units (roll call) - all PU reply with their data, then NCS transmits
Link 11 limitations
Operates on single Frequency
More participants slow the net
If you lose the NCS you lose the whole data link.
All members recieve all data
Advantages of link 16
Multi frequency
Nodeless (doesn’t matter if you lose any aircraft, you still maintain Data link)
Increased data rate
Reduced terminal size
What message formats do link 11 and 16 use?
11 - M series
16 - J series
What system does a link 16 operate?
Semi duplex - broadcast system
Explain Time division multiple access (TDMA)
Units are allocated time slots
One transmit, the rest receive
Some units have more information to pass so more time slots allocated
Every minute of every day broken down into cyclic windows
Epochs> Frames> timeslots (7.81miliseconds)
1 frame = 12 seconds
What does JTIDS stand for?
Joint tactical information distribution system
What are the 2 catagories for JTIDS units?
Command and control
- more information to transmit so more time slots
- AWACS, major naval units etc
Non command and control
- fighter AC
- less information to transmit
What does AIS stand for?
Automatic identification system
What is the main purpose of AIS?
An automatic tracking system used on ships for identifying and locating vessels by electronically sharing data with other nearby ships, AIS base stations and satellites
What information will AIS include?
IMO number Type of vessel Position, course and speed Where it's from and going Gross tonnage
Who must have AIS fitted?
International voyaging ships over 300 tons
Non international voyaging ships over 500 tons
All passenger ships regardless of size
What does AIS utilise to transmit information?
SOTDMA
Self organized time division multiple access
What is the advantage of self organized time division multiple access?
You didn’t need a central station to assign slots or time synchronisation
What are airborne uses for AIS?
Fishing fleet monitoring and control
Maritime security
Search and rescue
Fleet and cargo tracking
What is IBS?
Integrated Broadcast service
What is IBS-I?
Integrated Broadcast service interactive
Reports unevaluated intelligence
IBS- S?
Integrated Broadcast service Simplex
Time critical evaluated intelligence
What is SSSB?
Ship shore ship buffer
Acts as a relay between CRC link 1 to link 11 naval vessels (and airborne assets)
Transferring data between CRC (control reporting centre
Limitations of SSSB
Not all link 11 data can be transferred to link 1
Further coordination may be required through voice
What is an ELNOT?
ELINT notation
A123Y
What does the first letter of an ELNOT do?
Platform and originating block
What does the last character of an ELNOT do?
Indicates family relationships
What are the Red first letter codes?
A-H
A - airborne B- Ground C - Ship borne F- Ground/Ship T- temporary notation
What are the blue first letter codes?
M-P
M- airborne N- ground O - ship borne P- ground/ship W- temporary notation
What letter range is given to commercial emissions for first letter ELNOTS?
I-K
What is L first letter ELNOTS?
Unknown
What is K first letter ELNOTS?
Comnav
What is G first letter ELNOTS?
Data link
What is J first letter ELNOTS?
ATC
What is I first letter ELNOTS?
COMAIR
What are the last character ELNOT?
Z - unique emission, no family members or one of a kind
A-W - 1st-23rd family members
X - unknown position
Y- ambiguous emitter
What may a joining message contain?
Callsign Weapon loadout Serviceability ETA Latest SPINs changes
What may a handover message contain?
Current tasking Estimated time off task Threats in area Weather in area Other callsigns in area
Name 3 functions of TDL within a C2 environment
Surveillance
Reconnaissance
Operational intelligence
3 main characteristics of TDMA?
Epoch frame timeslots (7.81s)
Units assigned which timeslots through timeslots assignment
Automatic and transparent to operator
What are the moan operating differences between link 11 and link 16
Link 11 uses roll call (NCS roll calls all PU which reply with data then NCS transmits own)
Link 16 uses TDMA
What AIS architecture is there?
AIS tranciever on ships
SOTDMA
Display
