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Unit 5-4


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(816) What type of multiplexing is used in the closure, analog, digital, and video/trigger/data channels?
Time division multiplexing
(817) The most common type of modulation used in remoting is...
Amplitude modulation (AM)
(818) Which converter is used in both the precision approach radar (PAR) shelter and radar approach control (RAPCON) remoting equipment to convert the parallel 32-bit data words to serial data and back again?
Digital-to-digital (D/D)
(818) In the AN/GPN-22 precision approach radar remoting system, which channel is not remoted to the radar unit?
(819) Where are the modulated subcarriers that represent the various types of inputs to the remoting circuits summed?
Remoting common channel
(819) In the remoting section of the precision approach radar, what are the four stages of the line receiver?
High voltage protection and balance adjust circuits, equalizer circuits, output amplifier and gain adjust circuit, and output buffer.
(820) The precision approach radar (PAR) indicator system indicates an aircraft's...
elevation, range and azimuth
(820) Azimuth and elevation cursors are curved on the precision approach radar (PAR) indicator to...
compensate for PAR offset from runway.
(820) Where is the reference reflector displayed on the precision approach radar (PAR)indicator system?
Azimuth portion only
(821) The main function of the refresh memory in the precision approach radar (PAR) indicator system is to...
maintain a flicker-free presentation for the display.
(821) In the precision approach radar (PAR) indicator the top and bottom half of the display respectively presents elevation and azimuth data versus...
range data
(822) With the exception of the signal generator mode, what position should the trigger switch be left in on the AN/UPM-145 Radar Test Set?
(822) The AN/UPM-145 output frequency can be adjusted between...
8.4 to 10.0 GHz.
(822) On the front panel of the AN/UPM-145 the potentiometer indentified as FINE, in the attenuation section, provides continuous attenuation adjustment of the test set radio frequency (RF) output signal level from...
+7dB to -15dB.
[816] What are the three basic methods of multiplexing?
(1) Frequency division.
(2) Time division.
(3) Phase division.
[816] Define multiplexing as related to computer operation.
Multiplexing is the process of transferring data trom several storage devices that operate at relatively low transfer rates to one storage device that operates at a high transfer rate so the high-speed device is not obliged to wait for the low-speed devices.
[816] Describe the types of multiplexing used in PAR remoting.
Frequency and time-division multiplexing combine more than one signal on one line buy assigning different frequencies and by allotting specific time intervals, respectively.
[817] In AM modulation, what varies the carrier amplitude?
The frequency and intensity of the modulating signal intelligence.
[817] In a 3-tone FSK message containing binary digital information, what does the frequency of 12kHz represent?
A sync pulse that indicates the start of a new message.
[817] What two types of modulation does the analog data undergo?
(1) PCM (Pulse code modulation)
(2) AM (Amplitude modulation)
[818] In the AN/GPN-22, what type of mutiplexing is used on all the signals being remoted?
Frequency-division multiplexing.
[818] Why use a D/D converter?
To serialize the parallel data for efficient frequency-division multiplexing, and to retun the computer data to parallel form.
[818] What are the five channels used for remoting? Why not use more or less then five channels to remote information?
The 5 channels are Voice, closure, analog, digital, and video/data/trigger.
The fewer channels the better, although, the five channels are natural groupings of similar data, so less than five channels would not be advantageous.
[818] What channel is not multiplexed?
The voice channel
[819] Above what frequency are the video frequencies attenuated?
[819] What frequency is the microwave carrier, and what signal modulates it?
8GHz or 15GHz.
The composite signal.
[819] If the cable remoting distance is changed, how can the new frequency compensation requirements be met?
Strap the line driver and receiver to the nearest 1,000 feet, and use the +/- 500-foot adjustable circuit in the receiver for any further requirement.
[820] Why are the cursors curved?
Because of the offset between the PAR and actual touchdown.
[820] How is decision height shown on the display?
A cursor intersecting the elevation cursor at decision height.
[820] What is signified by the distance between the designate symbol home position and the first range mark?
Distance to touchdown data.
[820] What does the reflector symbol represent, and where is it shown on the display?
An azimuth reference; on the azimuth half of the display.
[821] What component acts as the buffer between the TDC and display indicator?
The refresh memory
[821] What signal initiates each sweep, and how often?
The MPX (MultiPleX) trigger; it occurs at the beginning of every PRF (Pulse Repetition Frequency) period.
[821] How does the display indicator know where to paint the designate symbol?
The ball tracker provides X and Y position data.
[821] Describe how to "acquire" a target.
With the ball tracker, place the designate symbol over the target and press the ACQUISITION button. X and Y data from this is sent to the TDC (Target Data Computer), which then searches for the target.
[822] What is the maximum input to the AN/UPM-145 with a pulsed radar system?
50+ dBm
[822] What is the purpose of the PRF potentiometer?
It provides for continuous control of internal test set trigger pulse repetition rate from 50 to 5,500 PPS (Pulses Per Second).
[822] What is the purpose of the FM functional group?
To provide frequency modulation of the test output.
[822] On the AN/UPM-145 what is the purpose of the mode switch?
Provides for selection of test set mode of operation (radar, signal generation, or self-test mode).
[822] The frequency out of the test set can be adjusted between what values using the course and fine controls?
8.4 to 10.0 GHz
[822] What are the available pulse widths out of the AN/UPM-145 Test Set?
0.12 to 5.00 usec in 0.01 usec steps.

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