3D155 Volume 2 EOC Flashcards
Into what three categories can ATC radar systems be divided/
Air route traffic control
Terminal control area
Precision approach
In which ATC radar mission is an ASR used/
Terminal control area
Define range resolution
The ability of a radar system to distinguish between two close but separate targets at the same azimuth but different ranges.
Define azimuth resolution
The ability of a radar system to distinguish between two close but separate targets at the same range but different azimuths
Typically, what is the range and azimuth resolution of the PAR?
Range 100ft
Azimuth 1degree
What is the minimum distance between the ASR site and the touchdown point?
1/2 mile from the touchdown point
Why is receiver recovery time a factor in choosing an ASR site?
So that these areas do not fall within the area on the scope that is blanked out by receiver recovery time.
What is the maximum allowable separation of receiver and indicator with most landline remoting equipment?
10000 to 12000 ft
What is the ‘runway centerline’?
A line that bisects the runway and extends beyond it. It is the line an aircraft should follow in its approach
What is ‘left of the runway’?
The possible PAR siting area from the view of a pilot on a landing approach.
Define the term ‘touchdown’
An arbitrary point that has been designated as the point at which an aircraft would touch the ground if it were to maintain the glide path and course line given by the final controller during the landing procedure.
List the azimuth scan limits of the an/gpn-22
20deg in azimuth, but its coverage is from +10 to -10 with 0degree being the center of the antenna.
How can more than one runway be provided radar coverage when the pAR unit has such definite scan limits?
By using a turntable to turn the unit to bring the areas of interest into the radar scan.
If you need to cover two runways but can provide optimum coverage for only one, how should you site the unit?
locate the unit so that it gives the best coverage to your most important runway.
What is the purpose of radar reflectors positioned at surveyed points near the touchdown point adjacent to the runway?
to provide fixed targets to align the PAR system to the runway and provide a quick check on this alignment.
Which of the available reflectors for the GPN-22 are the most commonly used and the most critical to its operation?
The reference (tracking) reflector
PAR, List the two normal operating modes of the gpn-22
Scan and track modes
PAR, how many scan beam position intervals elapse before the radar goes into track mode?
24
PAR, How many targets can the radar track during a single track interval?
three
PAR, What term describes differences in azimuth and elevation prediction errors during tracking?
angle errors
PAR, In the GPN-22 PAR, describe the characteristics of the signal called ‘chirp’.
1 μsec RF burst swept 120 MHz within the operating frequency band.
PAR, how many narrow band filters does the an-gpn-22 par employ to convert a shift in IF to a range error signal?
24
PAR, Which signal is responsible for interrupting the TDC 1200 times a second?
The beam interrupt signal
PAR, During the tracking cycle, for how many targets can the TDC update azimuth, elevation, and slant range?
6
PAR, Name the technique used to track the touchdown reflector whenever all six track channels are being used.
Phantom track channel
PAR, name the two off-line test programs used for diagnostics
spa and tdc
PAR, which off-line test is used solely for the diagnosis of the TDC?
tdc
PAR, List the three modes of operation associated with the data loop operation.
input, output, and command.
PAR, what action does the tdc take whenever a peripheral that is addressed is busy?
The computer performs an alternate operation to conserve system operational time.
PAR, Which mode of data loop operation allows the tDC to receive data from a peripheral?
Input mode.
PAR, How many bits are contained in the data word from a peripheral?
32 bits
PAR, From where does the information that is entered into the site parameter panel switches come?
The initial site survey done by the site survey team.
PAR, What is the destination of siting information from the CDE?
The TDC.
PAR, How often is the site parameter data processed by the tDC
once every 2 seconds.
PAR, After selection of a target to be tracked, what action does an operator take to make the formal tracking request?
Depresses the ‘acquire target’ push button.
PAR, What action does the refresh memory unit take to identify the display making a request?
reformat the requested target’s range and elevation in the 20 bit word into a 32 bit word which includes a file identification code to identify the radar indicator requesting the acquisition.
PAR, What factor predicts the next track beam position and chirped local oscillator range?
The predicted target position.
PAR, What method does the refresh memory use to provide a flicker free display of the target symbol?
a 30 cycle refresh rate process
PAR, What is the primary operating voltage for the an/gpn22
50/60 Hz, 3 phase, 208 Volt, 57kVA
PAR, What voltage is always supplied for the an/gpn-22 evacuation alarm?
+12vDC from the battery or battery charging circuit
PAR, The 1A10 multivoltage power supply contains how many DC power supplies?
6
PAR, Which fault lamps illuminate upon sensing of an undervoltage condition in the 1A10 power supply?
front panel (fault) lamp on the 1A10 and the PAR fault lamp on the RSC
PAR, What is the significance of an OVER TEMP indication on the RSC?
it indicates the 1A10 is drawing excessive current or there is insufficient cooling.
PAR, Why is it prudent to attempt to power down and recycle a power supply if you have suspicions that is has gone into a ‘protect’ condition?
Because it may prevent you from replacing a power supply that is not defective.
PAR, Why is the TWT instead of a magnetron used in the gpn22?
because it provides high amplification over a wide range of frequencies which is something a magnetron cannot do.
PAR, Describe how the TWT amplifies an RF signal.
The twt amplifies through the bunching of electrons in an electron stream interacting with the RF signal energy on a helix with each causing amplification in the other.
PAR, The STAMO is a frequency multiplier that multiplies the input VHF drive signal by what factor?
48
PAR, Why use contiguous pulses?
To provide frequency diversity
PAR, how many transmitters can radiate into the antenna at one time?
only one at a time.
PAR, Which LED on the front panel of the low power transmitter monitors the input VHF signal?
the ‘TWT RF INP’ led
PAR, What determines the amount of RF drive applied to the TWT?
The setting of attenuator AT1.
PAR, What is the purpose of the TWT Modulator A6?
it is a pulse shaper and voltage amplifier. It contains a regulator and clamp circuit that produces a flat topped output pulse that is used to turn on the tWT.
Define a 3X fault.
A condition that may cause damage if it is allowed to persist or reoccur in rapid succession.
PAR, If a standby fault occurs, the transmitter cycles to what mode?
OFF mode.
In a typical ASR, if three faults occur within 30 seconds, what happens?
Transmitter operation is stopped and requires manual resetting.
PAR, Name the equipment that make up the antenna beam position control unit equipment and tell where each is located.
The ABPCU located in an equipment rack in the PAR shelter, and the APCU located in the antenna assembly.
PAR, What is the principal function of the interface equipment?
to generate appropriate phase commands to each of 443 phase-shifter elements of the antenna.
PAR, Where are the control signals and antenna beam position commands from the TDC routed?
to interface control circuits and TDC command data register logic respectively.
PAR, In scan mode, the antenna beam can be directed into how many separate beam positions?
439
PAR, What are the two methods for testing the ABPCU and APCU?
Offline and Online
PAR, How can the inputs from the TDC be duplicated during off-line testing?
by using the ABPCU front panel controls
PAR, Which off-line test analyzes the communication lines between the ABPCU and APCU?
rebound test
PAR, What is the purpose of the shift register test?
Analyzes each shift register and the associated parallel data input lines and reveals faulty block decodes.
What is the purpose of the high-power ferrite circulator (duplexer)?
It directs the RF from the transmitter to the antenna horn for transmission and directs the received sum channel RF energy to the receiver sum channel.
PAR, List the parts of a receiver-protector
Transmit/receive and STC section and two diode RF attenuators.
PAR, What is the condition of the STC attenuators just before transmitter firing a radar pulse?
all attenuators are switched ‘in’ to provide maximum attenuation of 50dB per channel.
PAR, The FET amplifier is turned off during what mode?
track mode.
PAR, What is the total frequency multiplication factor in the receiver front-end STALO?
48
PAR, In what mode of operation does the sum channel FET amplifier get bypassed?
track
PAR, What is the purpose of the UHF preamplifier?
the UHF amplifier mixer provides RF to IF conversion, low noise amplification, and IF image rejection for the sum, azimuth difference, and elevation difference signals.
PAR, What is the final result caused by the negative pretrigger pulse to the STC circuit located in the UHF preamplifier?
The resultant pulses from the STC generator provide the drive that switches ‘in’ the IF attenuators in the azimuth, elevation, and sum channels.
PAR, At what increments are the attenuators stepped down as range increases?
10dB steps
PAR, Where does the receiver front-end BITE signal originate?
in the transmitter, a sample of the RF drive signal is picked off from the signal chain at a point prior to the TWT.
PAR, What are the timing generator’s main functions?
to generate the radar timing, provide for fault isolation and alignment, and accommodate special tests under front panel control.
PAR, When does the timing generator schedule automatic alignment and fault isolation?
During the 93 usec of dead time between the BCP and the first PRF trigger of each dwell.
PAR, What does the online timing generator provide to the online REX and PAR system?
All timing and control signals.
PAR, The IF down-converter combines the sum with delta azimuth and delta elevation in quadrature to provide three outputs. What are they used for?
track error.
PAR, What functions does the error detector perform during the track mode of operation?
it performs the filtering, limiting, phase detection, a/D conversion, decommutation, and integration of the azimuth and elevation signals.
PAR, In the range track module, each filter is 1.5MHz wide and represents how many feet in predicted range?
6.25
PAR, What does the nonredundant interface use to determine the active channel of the receiver-processor?
The test results.
PAR, For what does the channel select logic use the fault summary word?
To determine the online channel.
PAR, The receiver control panel is divided into what three functional areas?
receiver status, special test, and test points.
PAR, All of the switches in the special test section are disabled until enabled by the special test switch with the exception of which switch?
The LN/LM switch.
PAR, When is automatic fault isolation performed?
During the radar dead time.
PAR, What is the time displacement of the input video channels to the SDC?
.5usec from each other.
PAR, What is the destination of the canceled, unipolar video out of the SDC?
The shelter control indicator group and the radar data transfer group.
PAR, What are the three operational modes for the SDC?
dmti, dvi, gated dmti modes
PAR, how does a phase detector differentiate between a fixed and moving target?
the fixed target return exhibits the same phase every return; the moving target, on the other hand, changes phase every return.
PAR, What is a major drawback of the single cancellation method?
The fixed targets are not always completely canceled.
PAR, How many scans are required for successful double cancellation?
three
PAR, What is the purpose of video integration?
to enhance the relatively weaker returns from longer range targets
PAR, What is the purpose of the second time around reduction circuitry?
To identify and blank returns from targets beyond the operating range of the radar (second-time-around clutter)
What are the three basic methods of multiplexing?
frequency division
time division
phase division
Define multiplexing as related to computer operation
The process of transferring data from 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.
What is the multiplexing process of sending two or more signals over a single path by assigning each signal a different frequency band?
frequency division
In AM modulation, what varies the carrier amplitude?
the frequency and intensity of the modulating signal intelligence.
in a 3 tone FSK message containing binary digital information, what does the sync pulse indicate
the start of a new message.
What two types of modulation does the analog data undergo?
PCM
AM
PAR, in the gpn22 what types of multiplexing are used on the various types of data signals being remoted, and in what order?
first time division multiplexing then frequency-division multiplexing
PAR, why do we use a d/d convert?
To convert the parallel 32 bit data words (that were transferred between the TDC and the display segment) to serial data and back again.
PAR, What are the five remoting channels, and why do we use five?
voice closure analog digital video/data/trigger channels The fewer channels remoted the better. the five are natural groups of similar data, meaning that reduction to less than five channels would not be advantageous.
PAR, What channel is not multiplexed?
voice channel
PAR, The video frequencies are attenuated above what frequency?
4 MHz
PAR, What frequency is the microwave carrier, and what signal modulates it?
8 or 15GHz; composite(baseband) signal.
PAR, If the cable remoting distance is changed, how are the new frequency compensation requirements met?
strap the line driver and receiver to the nearest 1000 ft in increments if 1000 (not to exceed 12000), and use the +-500ft adjustable circuit in the receiver for any further requirement
PAR, Why are the elevation glidepath cursors curved?
Because the display is plotting elevation angle versus slant range?
PAR, How is decision height shown on the display?
On the indicator along the elevation glidepath cursor.
PAR, What is signified by the distance between the designate symbol home position and the first range mark?
distance to touchdown data.
PAR, What does the reflector symbol represent, and where is it shown on the display?
an azimuth reference; on the azimuth part.
PAR, What component acts as the buffer between the TDC and display indicator?
RM
PAR, What signal initiates each range sweep, and when does it occur?
mpx trigger; at the beginning of every PRF period.
PAR, How does the display indicator know where to paint the designate symbol?
the ball tracker assembly provides X up/down, and Y up/down pulses to x and y axis up/down counters.
PAR, describe how to ‘acquire’ a target.
the operator places the designate symbol over the target and presses the acquisition button. x and y data from this is sent to the tdc, which then searches for the target.
UPM145, What is the maximum input to the upm145 with a pulsed radar system?
50+ dBm
UPM145, What is the purpose of the PRF potentiometer?
it provides for continuous control of internal test set trigger pulse repetition rate from 50 to 5500 pps.
UPM145, What is the purpose of the FM functional group
provides for frequency modulation of the test set output.
UPM145, What is the purpose of the mode switch?
provides for selection of test set mode of operation (radar, signal generation, or self test)
UPM145, the frequency out of the test set can be adjusted between what values using the course and fine controls?
8.4 to 10 GHz.
UPM145, what are the available pulse widths of the test set?
5.00 usec in .01 usec steps
UPM145, after initial turn-on, what is the recommended warm up period prior to using the test set?
5 minutes.
UPM145, what type of signals can the test set generate?
fixed or moving target, xband CW, pulse, and square wave signals, and triggered xband FM.
What receiver parameter does MDS check?
The smallest possible signal a receiver can detect or receiver sensitivity.
UPM145, What position is the DISPLAY SELECT switch set to when performing an output signal power adjustment/
RF SIG PWR (DBM)
UPM145, When the system is turned on or when R (rest) key is pressed on the keyboard, what pulse will the test set produce?
1.0 microsecond.
UPM145, if you enter a 6.00 microsecond pulse into the system using the keyboard, what will happen?
the displayed value will flash for 3 seconds because this entry is beyond the pulse width limit, and the test set will return to the keyboard entry mode.
UPM145, To get the MDS, you should increase the test set attenuation until the target does what?
disappears into the noise or ‘grass’
What values are added to compute the MDS?
Displayed attenuation, rf cable attenuation, and radar coupler attenuation.
GPN20, What is the input power requirement for the gpn20?
120/208 VAC, 50/60 Hz, 3 phase, 4 wire, 9 kVA per phase.
GPN20, What unit provides under-voltage and over-voltage protection for the an/gpn-20?
a7 AC protect unit
GPN20, what two units provide regulated DC voltage to the transmitter, receiver, and processor?
a5 and a15 preregulators
GPN20, which circuit breaker provides power to the battery charger?
a6cb7
GPN20, during emergency power distribution conditions, how many obstruction lights are on?
only one.
GPN20, how does a staggered prf effectively eliminate blind speed?
by introducing an apparent change in target speed.
define blind speed.
a target speed at which successive radar returns change phase by 180 degrees or half a wave length.
GPN20, how are triggers developed at specific times in the digital synchronizer?
decoder gates initiate a trigger at predetermined counts.
GPN20, how are different PRFs selected?
By changing the count at which the reset pulse will start the count sequence again.
GPN20, how can two separate systems operate together through one antenna?
diplexers isolate the frequency components of each channel while timing between the two is synchronized; one channel acting as the master, the other the slave.
GPN20, Why are there no phasing problems between the master and slave channel videos?
system clocks are derived form the same source.
GPN20, master channel transmitter pulses occur how many microseconds before the slave channel pulses?
1.4 usec.
GPN20, What are the terms used to describe the circuit that receives a trigger and modifies it to fire the modulator assembly?
Modulator driver, modulator control assembly, and trigger amplifier.
GPN20, in the GPN20, what signal discharges before pulse modules?
SCR gate
GPN20, how is the output of the hvps regulated?
by controlling the amount of conduction time for each of the six SCRs
GPN20, what signal does the modulator control use to initiate the actual firing of the transmitter?
the PRE RF Trigger
GPN20, what happens to the transmitter when one pulse module fails?
The transmitter continues to operate at a reduced power level.
GPN20, What is the output of the magnetic pulse modulator?
narrow (.8 usec) negative 5.5 kV pulse to the pulse transformer.
GPN20, why do we control the amplitude of the pulse modulator output?
to provide superior frequency stability and improved operation of MTI receiver circuits
GPN20, what is the average value for magnetron current, and of what is the magnetron current meter a good indication?
approximately 30mA; the transmitter output power
GPN20, what is the sample period for a 3x fault?
61 seconds.
GPN20, what does a duplexer do?
it allows the use of a single antenna for both transmitting and receiving.
GPN20, explain the difference between ASR high and low power diplexers.
high power is pressurized and suitable for both transmit and receive signals; low power is suitable for received signals only.
GPN20, what does using the diplexer with the gpn20 radar permit?
permits a frequency diversity that greatly improves target detection.
GPN20, what is the function of the filters in the diplexer?
isolation between channels and to filter magnetron side lobes.
describe the function of each of the following antenna units. pedestal encoder reflector feedhorn polarizer
pedestal-supports the antenna
encoder-produces azimuth data
reflector-shapes the rf pattern into a narrow beam
feedhorn- radiates rf energy toward the reflector
polarizer-select the mode of radiation (circular/linear)
What device is used to make the transition from fixed to rotating waveguide?
rotary joint
GPN20, what can be done to the antenna beam to increase the azimuth resolution?
make the beam as narrow as possible.
GPN20, what is the purpose of the passive feedhorn?
it raises the received beam pattern by 3.5deg
GPN20, what could you expect if using the clutter reducing aspect of a dual-feedhorn system on a mountain range reaching 4deg above the horizon?
the amount of clutter would be reduced by the amount which is below 3.5deg
GPN20, What are the two reasons for tilting the antenna?
First, to minimize the effects of local terrain on the radiation pattern. Second, to improve the strength of the average return from an aircraft by making the strongest part of the radiation pattern coincide with the glide slope of a particular type of aircraft.
GPN20, how will the final optimum antenna angle be determined when tilting?
survey and flight check
GPN20, where are the encoders located in the an/gpn-20 ASR?
in the rotary joint.
GPN20, what purpose do ACPs and ARPs serve?
determine the angular position of the antenna.
What does the step-twist section of waveguide provide?
a gradual twist between the waveguide feed and the rectangular transformer section.
in what direction will the circular polarized reflected energy from a symmetrical target (rain drops) be polarized?
In opposite direction of that of the transmitted energy.
GPN20, at what point in the rf return path is the active or passive return selected for processing?
the antenna pattern switch.
GPN20, why is the LNA placed ahead of the signal mixer?
to reduce the signal-to-noise ratio of the receiver.
GPN20, what does the gpn20 ASR use to carry out Rf-to-If conversion?
A crossbar mixer
GPN20, what receiver component generates most of the crystal current flowing in the signal mixer?
the STALO
GPN20, a preamplifier with a broad bandwidth is often preferable for what application?
MTI applications
GPN20, what does the normal IF amplifer provide?
if amplification, bandpass filtering, video detection, and video amplification.
GPN20, what is the primary purpose for using the log IF amplifier and circular polarization?
to prevent weather clutter from obscuring desired target returns on the PPi displays.
What are the three separate signals applied to the MTI IF amplifier?
- IF from the preamplifier
- reference (COHO) oscillations.
- lock-test pulses
GPN20, why must all signals be at the same amplitude when they leave the IF strip?
because the phase detector is sensitive to an amplitude change as well as a phase change
GPN20, quadrature MTi is designed to overcome what weakness?
blind phase.
GPN20, within the phase detector, the IF signals are compared in relative phase to what signal?
COHO oscillator signal
GPN20, just prior to firing the magnetron, the COHO is gated off by what trigger?
PRE RF trigger
GPN20, the amplitude and polarity of phase detector video output is dependent upon what?
relative phase between the two IF input signals.
GPN20, the MTI IF gain controls should be set for what condition?
the best signal-to-noise ratio
GPN20, what does the recovery slope on the STC wave shape represent?
the rate at which an STC wave shape increases video gain with an increase in range.
GPN20, what factor determines the baseline of the STC waveform?
IF gain level
GPN20, what is the purpose of the FTC circuit?
reduces the effects of large blocks of video, including precipitation clutter.
GPN20, a relative (or difference) AFC circuit controls what component to maintain a 30MHz output frequency?
the magnetron output frequency.
GPN20, The AFC error signal is derived from the difference between what two signals?
The STALO output and an attenuated portion of the transmitter pulse.
GPN20, What is the output of the phase detector?
A positive or negative voltage, referenced to zero volts, proportional to the amount the applied IF pulse is below or above 30MHz
GPN20, what is the area of no correction called?
null or dead zone
GPN20, what happens when the ASR transmitter frequency is 5MHz from its normal frequency?
the AFC circuitry stops tuning and shuts off the transmitter.
GPN20, what happens to the frequency error signal in MAN position?
the error voltage is disconnected.
GPN20, what subassemblies does the log test generator module contain?
- noise generator subassembly
- random speed target generator subassembly
GPN20, what is the purpose of the log test generator outputs?
permits evaluation of the receiver and processor circuits
GPN20, where does the master timing signal (PRFCK) originate?
the continuously running 30MHz crystal controlled oscillator of MTI control, A27 card
GPN20, the .467 usec RC provides range resolution of two targets separated in range by approximately how many feet?
230 or more
GPN20, what are the two functions of MTI video condition?
conditioning for the receiver coherent video and generation of test signals to check the quantizers and dual cancellers
GPN20, define quantization
the conversion of an analog signal to digital signal, with steps between specified levels
GPN20, what functions does the A48 MTI LOG-FTC card perform?
eliminates blocks of weather clutter at least nine range cells long and delays all MTI words five range cells or 2.335 usec, even if the card is turned off.
GPN20, in what circuit card is either log or normal video selected?
normal LOG-FTC A32
GPN20, what is the purpose of the diversity combiner A38 circuit card?
combine master and slave channel videos
GPN20, what three factors are used to determine the radar’s subclutter visibility?
prf, antenna bandwidth, and speed of antenna rotation
GPN20, identify three types of canceller configurations
single canceller, cascade canceller, cascade canceller w/feedback
GPN20, how does the velocity shaping canceller compare to the cascade canceller?
provides better subclutter visibility (SCV) by reducing the MTi receiver response to unwanted slow-speed targets
define subclutter visibility.
the ability to detect a small moving target in ground clutter. It is a figure of merit for an MTI system, expressed in decibels.
GPN20, what does ‘RAG’ stand for, and what does it allow radars to do?
Range-azimuth gating; enables radars to change operating modes continuously with respect to azimuth and range at preselected values.
GPN20, what are azimuth strobes used to indicate?
runway, air route, or approach pattern.
GPN20, How is RAG programmed?
by means of patch cords and PWB-mounted SPST switches.
GPN20, what is the maximum distance of landline between ASR and operations sites?
12000 ft
GPN20, what is received by the remote site unit?
MTI and normal video, radar trigger, and ACP and ARP
GPN20, what happens to the memory control in the even to of a power failure? what is the benefit?
a temporary power supply provides voltage to keep the memory energized for 10min. allows the system to be placed on backup power and re-energized without the need to reset controls.
TPX42, what subcomponent ensures time coincidence between SIF video and radar video?
the coder-synchronizer.
TPX42, what is consider the major output of the coder-synchronizer.
mode interrogation pulses (P1, P2, P3)
TPX42, what is the purpose of the interconnecting group?
it accommodates two receiver/transmitters and provides the electrical and mechanical interface between the receiver/transmitter and the rest of the TPX42 interrogator set.
TPX42, what is the function of the interference blanker?
it cancels nonsynchronous replies-commonly called FRUIT.
TPX42, how does RABM function?
it accepts interrogations from the beacon transmitter and, in turn, produces a reply.
TPX42, what characteristics of the RABM restrict its use to within 3 miles of the radar site?
It’s low power output and receiver sensitivity.
TPX42, what factors determine at what range the RABM test target is displayed?
the total distance the RABM is remoted from the radar site and the setting of the range delay switches.
TPX42, how do we keep the rabm from responding to side-lobe interrogations?
side-lobe interrogations are suppressed by either an azimuth gate or, if the unit is remote, a directional antenna.
TPX42, how is the receiver protected during transmission of the RABM reply?
the diplexer’s critical length cables let it act as an isolator between the transmitter and the receive channels.
TPX42, during initial installation of the RABM 3 miles from the transmitter site, how much attenuation should first be used? why?
maximum attenuation, 60 dB. This prevents the probability of damaging the receiver input circuits.
TPX42, what is the function of the PWD?
it eliminates pulses less than .36 us wide and standardizes the P1 and P3 pulses to a .5us output.
What purpose does the mode latch serve?
it educates the encoder as to which mode of interrogation is being processed.
TPX42, what factors determine the reply code and the type of reply the RABM transmits?
clocks from the counter, the enable gate from the delay comparator, mode decode information from the mode latch, and reply response codes from the code switches.
TPX42, what conditions must be present for the trigger separator to provide the operational receiver/transmitter with challenge video?
it must receive two enabling signals-challenge enable and range error enable.
TPX42, receiver video is sent to what assembly from the channel select relay?
interference blanker.
TPX42, what is the purpose of the RF switch and directional coupler?
they provide calibrated transmitter energy fro VSWR measurements, route the on-line receiver transmitter energy to the ISLS switch or diplexer, send receiver/transmitter to the dummy load.
TPX42, with what type of radar system is the ISLS switch used?
radar systems that have a capacitively coupled rotary joint and a separate Omni directional antenna.
TPX42, what is the purpose of the GTC delay gate? and when doe sit start?
it inhibits the receiver during transmission of mode interrogations. It’s produced in the internal trigger mode only.
TPX42, at what frequency does the DRO oscillate?
4120 MHz
TPX42, what is the effect of turning the GTC switch on?
the leading edge of the gain controlling signal is sloped, providing a maximum of 50 dBm attenuation to reply code trains of close-in targets then recovering in about 6 dBm octaves until the maximum gain level is reached.
TPX42, what conditions must be met to rest the video monitor lamp?
there must be a raw video monitor pulse, interrogation pulses, and a self-test gate.
TPX42, what is the major signal output of the signal processor, and where is it routed?
compensated defruited/common video; the video signal processor.
TPX42, what is the purpose of the video signal processor?
it decodes the reply code video and checks for various special replies and conditions.
TPX42, what aircraft target information is stored in the VSP memory?
mode identity, range, azimuth, and altitude.
TPX42, what does ‘beamsplit azimuth’ mean?
it represents a point in azimuth about midway between the on-target azimuth position and the end-of-target azimuth position.
TPX42, bracket video should be time coincident with what other video?
radar returns.
TPX42, where is barometric pressure manually entered?
master indicator.
TPX42, how is random noise removed form the separated video output of the trigger separator?
The signal is sent through a comparator circuit set at a reference level above the random noise level but below the minimum video amplitude.
TPX42, what is the purpose of the trigger decode logic circuits?
they determine which interrogation mode is being processed.
TPX42, What is the purpose of the video signal processor?
it produces one target report message per antenna revolution for each responding aircraft within range.
TPX42, when does a true garble condition exist?
when the replies from two or more aircraft overlap and are synchronous.
TPX42, what subunit in the VSP performs quasi-defruiting, and when does it occur?
the TDU; when the interference blanker isn’t operating or is in standby mode.
TPX42, what test set can display the output of the tRU and is used to troubleshoot the VSP?
the TPM-32
TPX42, normally, what determines the power level at which the IR units are operated?
an ATCLS evaluation or local FAA guidelines. low power is almost always sufficient.
TPX42, if the target load indicator comes on when a range error is detected, what does it indicate?
IDP is processing more than 128 targets or the PIDP II is processing more than 300 targets.
PIDP II, what is meant by the term ‘tag’ on the radar display?
a dynamic presentation of target data fixed to all radar replies.
PIDP II, what are the contents of a maximum message tag?
position symbol, leader, a 4 line tag containing aircraft identification, reported beacon code, reported altitude, aircraft class, ground speed, and a controller commentary or system warning flags.
What are the contents of the tabular presentation of auxiliary data that’s available for display?
operating parameter information, arrival/departure data, drop/suspend data, and preview data.
PIDP II, what capability does the quick-look feature provide?
it lets the controller ‘quick-look’ the full data blocks of all tracked targets at any other control indicator group position.
PIDP II, what is the advantage of having two operator keyboards per control indicator group?
it lets one controller work active traffic and the other controller perform flight data entry/modification, and handoffs as operational traffic loads dictate.
PIDP II, list the three safety monitoring features on the PIDPII system.
altitude monitoring, MSAW, and conflict alert.
PIDP II, what information is handled by the NAS modem unit in the OL475/T processor?
exchange of handoffs, flight plans, departure, and test messages between the PIDP II and the FAA NAS enroute center.
PIDP II, what allows communications between the system control console and the PDP?
Blast emulation software.
PIDP II, list the 3 input signals to the PIDP II from the TPX42 beacon system.
- frequency-shift keyed data
- azimuth change pulses
- azimuth reference pulses
PIDP II, what is the purpose of the keyboard at each indicator?
it controls the display of data at the indicator position.
on the OD153 display, what is used to change cursor bearing and position of the range strobe?
The PEM
What system component is used to initialize the PIDP II system?
Master display
PIDP II, the low altitude alerting system contains how many geographic sectors?
1024
PIDP II, what type of indication does the air traffic controller receive if two conflicting targets have valid altitudes?
the audible alarm sounds and the data block flashes with the projected flight paths displayed in flashing dots and the word CONFLICT in the data block
PIDP II, what is the purpose of the NAS modem?
it allows data exchange via telephone lines between the terminal and NAs en route ARTCC centers.
PIDP II, at what rate does the NAS modem transmit data?
2400 baud
PIDP II, how many displays can an interface card communicate with?
8
PIDP II, when does data transmission happen between the CPU and the display interface?
during generation of a sector interrupt, which occurs every 11.25 degrees from north (0 deg)
OD153, what does the small circle symbol represent?
a nonselected target that is not tracked by any other indicator.
OD153, how many character liens may be displayed for a nonselected target?
2
OD153, What is the symbol for a controlled tracked target?
the letter designator of the indicator tracking the target
OD153, what is the purpose of the preview area?
it displays the keyboard messages entered by the operator and lets you edit the data before entering it into the system.
OD153, what is the maximum number of arrival/departures that may be displayed?
10
OD153, where are cursor and range strobe readouts displayed on the operating parameter list?
on line two of the operating parameter list.
List 3 special replies and their codes.
- hijack (7500)
- comm failure (7600)
- emergency (7700)
OD153, at what range does the data processing circuit refresh synthetic data?
Nominal 25Hz
OD153, Input data is arranged in how many sectors, what do they represent?
32 sectors that represent 360 degrees of antenna rotation.
DBRITE, what two sets of equipment make up the dbrite system, and what does each consist of?
operational, equipment consisting of the tower equipment and the equipment that interfaces with the radar and the ATC automation systems.
maintenance, equipment that consists of a maintenance panel and maintenance monitor.
DBRITE, how is the composite video signal generated?
aircraft range and azimuth PPI information are processed in the DSC. here the information is mixed with synthetic alphanumeric data to generate the composite video signal.
DBRITE, what is the purpose of the keyboard and PEM?
the keyboard allows entry of data and commands, while the PEM is primarily a two-axis control used to identify or position items on the display.
DBRITE, what is the purpose of the PS&J box?
it is used as a power source and the interconnection point for other DBRITE operator control equipment.
DBRITE, the ps&j box power supply provides dc power to which assemblies?
rcu
dcp
ps&j box logic board
keyboards and pem
DBRITE, what functions are performed by the ps&j box logic board?
multiplexes data from the rcu, dcp, and keyboard/pem before its sent to the DSC for processing.
DBRITE, list functions tested by the logic boards online BIT.
analog multiplexing.
a/d conversion of the pem inputs
power supply voltage outputs
DBRITE, list the components of each DSC
interface boards ppi board synthetic board control panel dc power supply
DBRITE, what happens when the BIT TEST switch is set to the BIT position?
DSC module is off-line and is running the offline built in test function regardless of the setting on the maintenance panel video select switch.
DBRITE, how many tower display units can be driven by a DSC?
4
DBRITE, where are the negative-going and positive-going sync signals separated form the video?
in the video sync assembly.
What is RIA?
a physical interface between a modem and a data cable either from the tower ps&j box or from the DSC cabinet.
DBRITE, what determined which type RCU is used?
the automatin system that’s connected to the DSC cabinet.
DBRITE, all operating voltages required by the keyboard and PEM are furnished by what assembly?
the ps&j box
DBRITE, what are the two functional elements of the BIT feature?
online and offline
DBRITE, what BIT functional element does not require you to intervene during diagnostic tests on an operational DBRITE system?
online
DBRITE, when an internal error is detected on the synthetic board during online BIT, what’s the probable cause?
the microprocessor is performing illogically.
DBRITE, what is the sequence of tests during off-line BIT?
synthetic board is tested, then the interface board, and finally the ps&j box.
DBRITE, after a test sequence diagnostic display, what step must be taken before continuing the tests?
The BIT ADV switch on the DSC maintenance panel must be pressed.
