EO-7(2) Flashcards
Why classify radars and signals by function?
Can help sorting through numerous signals to determine if weapons systems are present, allows a platform to preform in different ways based on the environment
Identify some examples of “Search Radar” systems:
Early Warning (EW), Height Finder (HF), Surface Search (SS), Navigation (NA), Range Instrumentation (RI), Meteorological Radar (ME), Over-the-Horizon Radar, Synthetic Array (Aperture) Radar (SAR)
Identify some examples of “Threat Radar” functions:
Target Acquisition (TA), Target Tracking (TT), Fire Control (FC), Airborne Intercept (AI), Anti-Aircraft Artillery (AA), Multi Function (MF), Missile Guidance (MG)
Does early warning detect targets at a close distance or far away?
As far away as possible
What system typically uses large PDs and circular scans? (can be air, land, or ship borne platforms)
early warning (EW)
what radar is designed to determine altitude of an airborne target
height finder
height finders are usually co located with what radar?
EW
Surface Search (SS)
Short range system that provides tracking data on ships for coastal defense or vessel movement control.
what radar group does harbor search (HS) and coastal search (CS) fall under?
surface search (SS)
Primarily used to prevent collisions
navigation (NA)
provide terrain surveillance by detecting and identifying targets like tanks, trucks, and people.
Battle field surveillance (BS)
Battle field surveillance (BS)
Tend to be low power, man portable systems. larger ones can be mounted on vehicles or aircraft.
Acquires and automatically tracks airborne targets to provide trajectory information on objects of interest
range Instrumentation (RI)
used to locate precipitation, calculate motion, and estimate its type. (snow, rain ect) (Most use pulsed doppler radars)
meteorological radar (ME)
what causes the limitation of line of sight for most radars
the curvature of the earth
type of radar used to detect and track targets from beyond the horizon
over the horizon radar (OTH)
What are the 2 types of OTH radars?
Sky wave and ground wave systems
Explain skywave systems
Uses certain angles and certain RFs (usually 3-30 MHz) to “bounce” radio waves off the ionosphere and back to Earth to targets beyond the horizon.
What factors affect the changing ionic densities?
Time of day, time of year, solar activity, weather
Explain ground wave
Uses lower frequencies (below 3MHz), uses atmospheric layers as a waveguide “ducting”
Explain synthetic array (aperture) radar (SAR)
transmits pulses, adds the returned pulses together to get larger “picture”
Which radar does terrain imaging, and ground mapping?
Synthetic Array (Aperture) Radar (SAR)
used upon initial detection of a target to refine angle and range measurements
Target acquisition (TA)
Used to maintain the location of a target by constantly calculating the targets range, angle, and velocity
Target Tracking (TT)
Explain Fire Control (FC)
designed specifically to provide info about a target to a fire control system in order for how to direct weapons to hit the target (identifies target’s azimuth, elevation, range, velocity)
What is a radar with an air to air role, typically housed in the aircraft’s nose cone?
Airborne intercept (AI)
Anti-Aircraft Artillery (AA)
used to determine adversary aircrafts angle, and range and projected path to be transmitted to a computer and used to direct weapons to the target
Multi Function (MF)
used to perform multiple tasks, can perform different functions. ex. target detection, acquisition, tracking, warheads vs. decoys (sometimes called MPARs)
What does MPAR stand for?
Multi-function Phased Array Radar
Missile-Guidance Radar (MG)
Used to provide missile guidance and course correction to a missile as it moves toward its target
What is a missile?
Self-propelled guided weapon system.
Name the main missile system components:
Targeting/guidance, flight system, engine, warhead
What are the 3 categories for missile guidance?
homing, beam riding, and command guidance
What are the 3 homing guidance types?
active, semi active, and passive
What is it when a homing missile contains a radar transceiver. and has the ability to find and track a target autonomously?
active homing
What is the main benefit of an active homing missile?
The fire and forget capability
What is the main disadvantages of an active homing missile?
Equipment must be small, it’s expensive, and is only able to work at relatively short ranges.
only has a reciever in the nose come of the missile, which passively detects a radar signal from an external source.
semi-active homing
A semi-active homing missile is an example of what kind of radar system?
A bistatic CW radar system
Describe the advantage of a semi-active homing missile.
It is not weighed down by a transmitter and, therefore, has greater reach.
Describe the disadvantages of a semi-active homing missile.
The target must be “illuminated” during the entire flight, leaving the launch aircraft vulnerable to counter-attack.
missile guides itself based on emissions from the target itself instead of reflections from the radar
passive homing
Name an example of a passive homing missile.
Infrared homing (i.e. heat seeking)
what are the two missile remote guidance types
beam riding and command
What is the simplest method of missile guidance?
beam riding
a transmit antenna on the ground points a beam at the target. the missile adjusts itself to keep in the center of the beam
beam riding
one radar is used to track the target another is used to track the missile
command
Command guided missiles can receive what 3 types of information?
- missile and target location
command info for missile: the missile contains an onboard computer that calculates course corrections based on data received
missile and target
command info for missile: has to have an internal navigation system to determine it’s own location. uses data along with recieved target location to calculate course corrections.
target location only
command info for missiles: course calculations made by parent radar, sends commands to missile. (pitch, yaw, roll, as well as arming and detonation commands)
steering commands
What are the common methods in relation to encoding schemes for command guidance?
pulse duration (PDM), pulse position (PPM), pulse code modulation (PCM), amplitude modulation (AM)
The process in which the duration, or width, of each pulse is varied in proportion to the amplitude of a modulating waveform
pulse duration modulation (PDM)
What is the most common use of Pulse Duration Modulation (PDM)?
Used to control servomechanisms inside of missiles.
Way to save wasted energy from the PDM but still convey information. Simply transmits the edges of the PDM pulses.
Pulse Postion Modulation
Remote Controlled Servos
Used to provide actuation for various mechanical systems (i.e. steering of a car, rudder of a boat)
PPM typically uses a consistent timing interval known as?
Frame time
What is sent at the beginning of each frame to maintain a timing reference for command guidance?
frame markers (reference pulse group)
What is a broad category of modulation that uses pulses to create binary codes?
Pulse code modulation
PPM- PCM
uses a series of closely spaced pulses to pass info. reciever decodes as 1 or 0, depending on the presence or lack of in the sequence.
FSK-PCM
changes the RF of the pulses in order to convey info. (Higher freq might indicate 1, lower may indicate 0)
PSK-PCM
phase shift 180° imparted during the transmission of the pulse, position and duration of the phase shifts translates into binary.
