Radar Fundamentals Flashcards
What is Radar?
A radio detection device which provides information on
- range,
- azimuth,
- elevation of objects.
What is azimuth?
- direction of a celestial object from the observer,
- expressed as the angular distance
- from the north or south point of the horizon.
What is Primary Radar?
- Radar transmits radio pulse
- Part of pulse hits any object with mass
- Is reflected back to the radar
- information is displayed at facility
What is Secondary Radar?
- object to be detected (normally aircraft) has cooperative equipment,
- known as a transponder.
What is Ground Clutter?
- pattern produced on the radar scope
- by ground returns
- may degrade other radar returns in the affected area.
What is an MTI?
Moving Target Indicator
What is a Moving Target Indicator?
- permits radar scope presentations
- only from targets
- in motion.
What is Polarization?
- radar antenna configuration that
- determines the motion of
- radio energy as it is transmitted.
What is Jamming?
- disruption of radar display
- or radio reception
- by electronic or
- mechanical interference
What is a False Target?
- Target that lacks
2. validity or authenticity.
How is a False Target often produced?
- temperature inversion or
2. Anomalous Propagation.
What are the four components of Radar?
- Transmitter
- Antenna
- Receiver
- Display
What does the Transmitter do?
Generates radio pulse
What radar component generates a radio pulse?
Transmitter
What 3 things does the Antenna radar component do?
- Focuses the pulse
- broadcasts the energy.
- Collects reflected energy.
Does the Antenna have a blind spot directly above it?
Yes
What radar component focuses the radar pulse, broadcasts the energy, and collects the reflected energy?
Antenna
What does the Receiver radar component do?
- Amplifies returned energy.
2. Converts to a video signal.
What radar component amplifies returned energy and converts it into a video signal?
Receiver
What 2 things does the Display radar component do?
- Presents the video signal.
2. Displays position and movement of targets.
What radar component presents the video signal and displays position and movement of targets.
Display
What is MTI blind speed?
- Aircraft flies directly towards/away from the antenna at a certain speed.
- Can reduce target’s strength.
What is tangential course?
When the aircraft flies in an arc, remaining the same distance from the antenna.
Why is tangential course a potential problem?
- MTI will think the target isn’t moving since the range isn’t changing
- this would weaken the target’s return signal.
What are the two forms of Polarization?
- Linear
2. Circular
What is Linear polarization?
- Normal radar transmission
- cause and echo from anything with mass.
- Displays all reflected signals.
- Provides strongest echo return.
- Allows display of precipitation.
What is Circular polarization?
- Energy pulse rotates,
- filters out certain echoes.
- Helps reduce/eliminate returns from weather.
What are the 5 phenomena that can adversely affect the presentation of primary radar targets on a display?
- Anomalous Propagation
- Temperature Inversion
- Electronic Interference
- Jamming
- Target Fades
What causes Anomalous Propagation?
Moist or dense air masses
Where does Anomalous Propagation frequently occur?
Over water
What happens in an Anomalous Propagation phenomenon?
- radar beam is bent away from dense/moist air mass.
- Most commonly bent downward.
- Radar returns are displayed with range or azimuth errors.
What happens in a Temperature Inversion phenomenon?
- Warm air gets trapped above cold air.
- Warm air deflects the radar transmission.
- Creates interference/ground clutter/false targets.
What happens in an electronic interference phenomenon?
- Other energy emitting objects interfere with the radar signal.
- Different radar systems or channels can interfere with each other.
What are the two forms of Jamming phenomenon?
- Active
2. Passive
What happens in an Active Jamming phenomenon?
- Electronic disruption of the radar signal.
2. Creates clutter/interference on a radar display.
What happens in a Passive Jamming phenomenon?
- Large amounts of shredded metal (chaff).
2. Creates clutter on a radar display.
What happens in a Target Fade phenomenon?
- The radar gives weak returns on
- its edges/fringes or
- below the signal.
What are the 5 Components of a secondary radar system?
- Interrogator
- Antenna
- Transponder
- Decoder
- Display
What is the interrogator in a secondary radar system and what does it do?
- Ground based transmitter.
2. Requests a reply from transponders.
What is the antenna in a secondary radar system and what does it do?
- Broadcasts signal along with the primary radar antenna.
2. Usually mounted on top of the primary antenna (where present).
What is the transponder in a secondary radar system and what does it do?
- Aircraft based equipment.
- Replies to an interrogator’s request.
- Contains a 4 digit code assigned by ATC.
- Transmits speed and altitude to the ATC.
What is the decoder in a secondary radar system and what does it do?
Sends transponder replies to a radar display
What is the display in a secondary radar system and what does it do?
Electronic presentation of the secondary radar information
What are the 3 advantages of a secondary radar system vs primary?
- Less blind spots than primary.
- Longer range than primary.
- Echoes not degraded by ground clutter or weather.
What are the 3 disadvantages of a secondary radar system vs primary?
- Requires airborne equipment.
- Reception can be adversely affected by aircraft position.
- Provides no weather returns.
What are the 3 phenomena that can interfere with secondary radar?
- Transponder may be near obstructions.
- Ring around (false secondary targets).
- Interrogator signal is strong enough to elicit a response from transponders it isn’t pointing at.
What happens when the transponder is near obstructions in the secondary radar phenomena?
- Signal may reflect off nearby obstructions.
2. Creates a phantom response.
What happens when the Interrogator signal is strong enough to elicit a response from transponders it isn’t pointing at in the secondary radar phenomena?
- Creates ghost targets.
- Azimuth cannot be determined.
- Can create a ring around a radar site of ghost targets.
What are the 3 types of radar display?
- Analog
- Digital
- Video maps
What does the analog radar display show?
- Displays the actual radar returns.
2. Has the radar “sweep”; the primary radar signal rotating around the antenna site.
What does the digital radar display show?
- Targets are digitized; does not display the actual radar echo.
- Has no sweep.
What does the video map radar display show?
- Overlays depicting data
- Airports
- Airspace
- Obstructions
- Range Marks
- Etc.
What type of problematic phenomena can create false secondary targets?
Ring Around.
What does ring around cause?
False secondary targets.
