Pulse Flashcards
What is the time taken for a transmitting pulse to return?
The echo is proportional to the distance of the sound waves had to travel.
What does RADALT provide?
Provides height information for terrain directly below the aircraft.
What does the pulse Doppler radar determine?
Targets speed and direction of travel.
What is search radar used for?
Uses range and azimuth of target.
What is the continuous wave radar used for? (Missile control)
To illuminate the target with RF energy and usually shares the same antenna with the pulse radar.
In a radar block diagram, what component switches between transmitting and receiving?
Duplexer (Connects to the antenna).
When regarding the duplexer, what is the TR switch?
A TR switch is sensitive to the direction of flow of RF energy; it allows the energy coming from the transmitter to pass with negligible attenuation to the antenna, while blocking the flow to the receiver. In simple terms, it is a wave guide switch.
What are the 2 most common types of antennas?
- Parabolic (shape reflector) antenna (dish)
- Planar array
What is the parabolic (dish) antenna?
The parabolic antenna (also known as the ‘dish’ antenna) consists of a flared end section of waveguide (known as a ‘horn’) which directs RF energy onto a parabolic dish. The parabolic shape of the dish reflects the RF energy into a narrow beam.
What are the 3 main components of a parabolic (dish) antenna?
- Parabolic reflector
- Horn
- Radiated energy
What is the planar array?
Instead of employing a central feed that radiates the transmitted energy into a reflector, as in a parabolic antenna, a planar array consists of many individual slot radiators distributed over a flat surface.
C type display?
Elevation, Azimuth
Rotary joint - what is it?
Primary radar antenna is for a mechanical connection between a fixed section of waveguide and a section feeding a scanning antenna.
What component enables me to sample the transmitted RF energy?
Slot-Coupled Attenuator
Cannon plug and wave guide - Know the difference?
Be able to identify them by photos.
What does RADALT indicate?
Accurate reading at low altitude and low altitude warning.
How do we get a height indication on our RADLT system?
Transmit a CW and determine it off the time it takes to come back.
What component in the RADLT system loops my signal in test mode?
Delay unit / switch
How many pairs are there in the four beam Janice array?
2 pairs
Antenna array and rotor assembly - know the block diagram?
Know the block diagram.
Relevant frequencies for secondary surveillance radar?
The airborne transponder receives the interrogating signal from the ground station: 1030 MHz (and automatically arranges to transmit a response in reply). The reply is transmitted: 1090 MHz. In simple terms: 1030MHz transmit - 1090MHz reply.
How many antennas does a radar system have? And why?
2 antennas - 1 is transmit and 1 is receive.
What is a special reply pulse in the secondary surveillance system?
Temporarily changing reply chain - momentarily identify you in a busy airspace.
What does TCAS do?
Warn pilot of aircrafts that are present.
- Survellance
- Interrogation
Gives you:
TA
RA
What are the TCAS components?
Control panel
What is the difference between traffic advisory (TA) and resolution advisory (RA)?
Traffic advisory (TA) indicates a potential threat, while resolution advisory (RA) requires maneuvers.
What is the antenna transition in each quadrant?
90 degrees quadrants
What is the function of ADS-B and its transition frequency?
Broadcast surveillance system for location and identification of aircrafts. Transition frequency is 1090MHz.
What is the CDTI and its function?
Cockpit display Traffic information for situational awareness of aircraft in the area.
What does the GPWS control panel switch inhibit?
It provides situational awareness to terrain and predicts terrain.
What is mode 4?
Flying low and not ready to land - insufficient terrain clearance.
What is the ADC and what does it receive?
ADC receives validity signal, altitude rate, and mach information.
What should you know about GPWS?
Know the block diagram.
What is an important maintenance consideration when working with coax?
Blanking caps should be used to prevent FOD.
What are safety precautions when working with radar systems, particularly antennas?
- Do not touch with your hands
- Do not allow contact with metal
- Antenna pressure must be bled before removal
- Alert all personnel in the area that radar testing is to be carried out.
What is used when carrying out radar maintenance?
- Relevant maintenance documentation/manuals
- Local standing instructions.
What is the difference between ionizing and non-ionizing radiation?
Know the difference between the two signs.
Choke flange joint - components?
One flange is flat and one flange is enlarged (Has a groove 1/4 of a wave length deep cut).
Four beam Janice - Know the block diagram
Refer to the block diagram.
Four beam Janice array - What type of radar system does it use?
Doppler radar waves.
What does Doppler navigation provide us?
Ground speed and drift angle.
Four beam Janice array - How does it indicate accurate heading?
The track bisects the angle between the beams; the received signal of each antenna will be identical.
Indication that something has entered the TA space?
Sound - ‘traffic, traffic’.
What happens when I use the precision height bug to set an altitude?
Gives verbal/visual indication when you cross below the altitude.
How does secondary surveillance radar determine what mode is being interrogated?
Time difference between P1 and P3.
How do we determine that we are not in the main beam?
P2 is larger than P1
What type of antenna transmits our P2?
Omni directional antenna.
What information is included in the Mode S all call?
The second method only interrogates Mode S transponders and is known as a Mode S All Call. Aircraft responding to Mode S All Calls include their individual address (a 24-bit aircraft ID). TCAS computes the tracks of the responding aircraft and the flight crew are advised of the results via a display located in the cockpit.
What does all-weather intercept do?
The all-weather intercept system uses radar rather than optical means to search out a target. Once a target is found and selected, the radar tracks the target in range, elevation and azimuth and presents steering information on the indicator. This equipment may also provide a surface search mode of operation.
What is E scope?
E scope includes elevation and range.
How is the self-test for RADALT initiated?
The self-test function is initiated by pushing the on/off selector on the indicator.
What is the normal depression angle for the 2 beam Janice array?
The normal depression angle is 60-70 degrees.
What should you know about the 4 beam Janice array information display?
A memory mode operates automatically whenever the received signal falls below an acceptable minimum value or when the frequency shift falls outside the spectrum of the tracker.
IFF system - what test is used?
The IFF system contains Built-In-Test-Equipment (BITE).
What is mode 2?
Mode 2 is military aircraft identification, which can be changed in flight on larger aircraft, and uses a 4 digit octal ID code.
What can the ADS-B system be configured to broadcast?
The ADS-B system can broadcast geometric altitude, rate of climb/descent, and ground speed.
What does VHF navigation provide in mode 5?
VHF navigation provides glideslope information.
