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70 Cards in this Set
- Front
- Back
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Which part of a radar set sends out the RF signal? |
Transmitter |
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What's another name for the reflected radar wave? |
The radar echo, or simply the echo. |
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Upon what does the usefulness of a radar set depend? |
Its ability to measure distance in terms of time |
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How fast does a RF wave travel a nautical mile? How about a radar mile? |
6.2us and 12.4us |
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If the echo from a target returns in 930us, how far away is the target? |
75 miles |
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What are two basic problems that must be overcome in all radar sets? |
Having a powerful transmitter and receiver operating on the same frequency, and using a constant frequency signal. |
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Name the three radar systems that overcome the basic problems affecting radar sets. |
Frequency-modulation systems, pulse-modulation systems, and frequency-shift systems |
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In frequency-modulation system, how many signals are fed to the receiver at one time? |
Two |
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Describe the operation of the transmitter in a pulse-modulation system. |
The transmitter is turned on for short periods of time and off for long periods of time. When the transmitter is on, it transmits a short burst of RF energy called a pulse. When the pulse strikes the target, part of the reflected energy is returned to the receiver, where it's processed and displayed on an indicator. Since the transmitter is turned off after each pulse it doesn't interfere with the receiver |
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Upon what principle is the frequency-shift system based?
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Doppler
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How is the length of the electromagnetic pulses in a pulse-modulation system measured?
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In microseconds |
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How does a longer pulse in a pulse-modulation system affect power and range? |
Longer pulses have more power which makes it possible to cover a larger range of space.
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List the six basic radar set components.
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Power supply, synchronizer, transmitter, antenna, receiver, and indicator. |
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What's another name for the master timer in a basic radar set?
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Synchronizer |
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Which component of a basic radar set triggers the transmitter?
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Synchronizer
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Which component of a basic radar set produces short powerful bursts of RF energy?
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Transmitter |
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What do you call the device that connects the antenna to the transmitter and receiver? |
Duplexer, circulator, waveguide switch. |
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Which component of a basic radar set produces an IF signal?
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Receiver |
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Name four things that can be determined by the shape of the radar pulse?
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Range accuracy, minimum range, maximum range, and the resolution of the target. |
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Range accuracy primarily depends on which part of the radar pulse?
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The leading edge |
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What property is provided by a flat topped radar pulse of sufficiently long duration? |
Maximum range |
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What property does pulse duration determine? |
Minimum range |
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What is the relationship between pulse recurrence time(PRT) and pulse repetition frequency(PRF)?
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PRT=1/PRF |
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Whats the peak power of a radar set?
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The maximum power of the radar pulse of a radar transmitter. |
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Whats the average power of a radar set?
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The power of a radar transmitter averaged over the whole PRT. |
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What principle makes it possible to instantaneously sense and measure ground speed and drift angle?
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Doppler Principle |
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Describle the dopler principle involved when you listen to the whistle of a moving train.
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The frequency seems to increase as the train approaches and decrease as the train moves away. |
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What's the frequency shift when the transmitter/receiver is at a constant distance from an object?
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How does the frequency shift change when an object is closing in on the transmitter/receiver? |
Increases |
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object is moving away from the transmitter/ receiver? |
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What's a waveguide?
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A transmission line comprising a hollow conducting tube within which electromagnetic waves may be propagated.
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Name two types of waveguides.
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Circular or Rectangular. |
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peculiar to RF transmission lines. |
Copper loss, dielectric loss, and radiation loss. |
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What are two advantages of waveguides over other types of transmission lines? |
capabilities. |
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What is the dimension of the frequency determing wall for a waveguide with an operating frequency of 10MHz and a wavelength of 30 meters?
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What's the function of the choke joint?
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To provide a good mechanical and electrical connection bewtween waveguide sections. |
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What's the function of the dummy load? |
To simulate a resisitive load and changing the RF energy into heat energy, absorbinhg the power of the transmitter during tests. |
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What's the purpose of the directional coupler? |
To provides a means of coupling energy between the waveguide and the test equipment. |
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Define Dummy Load.
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Absorbs transmitter power during testing. |
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What factors do you compare to determine VSWR of a waveguide? |
Reflected power and the transmitted power. |
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operation of an electronic system? |
It will cause a mismatch that increseses the VSWR, reducing energy that will reach the antenna, reducing power output |
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What should you look for during maintenance of the waveguide system?
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Dirt, metal objects, other particles that mave have entered the waveguide and moisture
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How many beam patterns are utilized on the APN-59 Search Radar antennas, and what are these patterns called?
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Pencil and fan are the systems two beam patterns |
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Which system LRU contains servoamplifiers that furnish both pitch-and-roll drive signals to the antenna stabilization motors? |
Electronic control amplifier |
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Which LRU provides stabilized pitch and roll reference data for control of antenna orientation? |
Stabilization data generator |
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How high and wide is the beam pattern of the Color Weather Radar flat plate antenna?
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approximately 2.1 degrees high. |
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What LRU powers and controlsthe antenna assembly of the LOW Power Color Radar system? |
The RTP |
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What are the scan limits of the Low Power Color Radar system antenna? |
it scans 135 degrees in azimuth and +10 degrees to -15 degrees in elevation |
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What is the range the CARA system measures and displays altitudes?
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From 0-50,000 feet |
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How many antenna are used in the CARA system?
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Two identical antennas; one designated for transmit, and the other to receiver. Aircraft with an additional CARA system installed will have two additional antennas. |
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What is initiated each time power is applied to the CARA system?
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An automatic self test and alignment sequence
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What is the purpose of momentarily pressing the SET knob on the indicator? |
To initiate a self test. |
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what is adjusted to display zero feet when the aircraft is on the ground? |
The AID potentiometer, located on the upper right of the R/T |
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What increments will the digital altitude display on the CARA indicator display altitude? |
One foot increments from 0 to 100feet and 10 foot increments from 100-50,000 feet |
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if failure is detected in the CARA system, what word is displayed on the digital altitude display? |
FAIL |
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The radar altimeter control knob (SET) has how many functions? What are they? |
Three functions of an on/off control, setting the VALI indicator, and as a test button to check the system |
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During bright light conditions, what overrides the digital readout dimmer control?
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Ambient light sensor |
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The analog altitude pointer and dial is graduated in what increments?
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increments from 1,000 to 5,000 feet. |
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When the CARA systems self test is initiated by pressing releasing the SET knob, what does the indicator display for 1.5 seconds? |
The indicator pointer moves to 500 ft, the digital display reads 88888, and the R/T lamp is illuminated. The LO lamp will also illuminate if the VALI is set above 500 feet |
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If FAIL appears on the digital display and the analog pointer goes behind the mask, what LRU is most likely malfunctioning? |
The indicator |
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Whats a radar ground map? |
Pictorial map of the terrain. |
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What does weather radar provide? |
A visual indication of storm conditions at ranges up to 300nms. It also provides a means of determining the relative density of rainfall areas, ability to see storm areas in flight path, and distinguish corridors of relative calm through the storms.
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What is the Average operating power of LPCR? |
Average power is 11W or less. |
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How is target range determined? |
By measuring the time the radio waves take to each the target and return |
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What's the primary function of TF radar? |
To provide automatic terrain-following flight
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What's TA radar used for? |
To display all forward terrain at and above the aircrafts altitude
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Define Bidirectional coupler
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directions |
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Define Feed horn
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Reduces reflections by matching impedance of free space to the impedance of the waveguide |
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Define directional coupler
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Allows measurement of RF energy in one direction |
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Define duplexer
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receiver |
