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Unit 5-6


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(834) What air traffic control IFF/SIF component generates mode interrogation triggers?
(834) The mode interrogation pulses P1, P2, and P3 originate from the
(835) The range delay switches used with the range azimuth beacon monitor (RABM) provide a maximum delay of
15 7/8 miles
(835) In the RABM, which device isolates the receiver input from the transmitter output?
(835) What is the freq. of the transmitted output from the range azimuth beacon monitor (RABM)?
1090 MHz
(835) If too much attenuation is used with the RABM...
the RABM cannot detect an input
(836) In the transfer switching drawer assembly (TSDA), the amplitude normalizer circuits limit inputs to how many volts before routing the signals to other circuits?
5 volts
(836) In the TSDA, what condition causes a range error inhibit signal to be produced?
a drift of the RZR pulse outside of the window gage
(836) An interregator side lobe supression (ISLS) diplexer is used in lieu of an ISLS switch when the radar system has
only one DC-coupled rotary joint for IFF/SIF
(837) If the I/R unit is operated in internal mode, what, if any, is the function of the gain time control (GTC) delay gate?
to inhibit the receiver
(838) In the video signal processor, what is the name of the new azimuth computed between the on target (OT) and end of target (EOT) azimuths?
beamsplit azimuth
(838 What is the significance of the signal called bracket video?
it is a real time video presentation that should be time coincident with the radar target video returns
(839) What component in the video signal processor monitors for the possible interference condition called garble?
reply detection unit
(840) On the interrogator sex control (b-box), if the TARGET LOAD indicator comes on, its indicating that the PIDP II is processing more than
300 targets
(841) What is the primary advantage of having two operator keyboards for each control indicator group?
enables one controller to work active traffic and the remaining controller to perform flight data entry/modification, handoffs, etc
(841) What function of the PIDP II alerts the controller should the selected tracked targets deviate greater than +-300 feet from the controller assigned, or current altitude?
altitude monitoring
(842) In the PIDP II, what signal is used for synchronization of sector interrupts?
azimuth reference pulse (ARP)
(843) What service does the low altitude alerting system perform?
When a tracked target enters one of 1024 geographic sectors and is at or below the altitude set for the sector, the tracked target begins to flash and the audible alarm is sounded
(843) Coast/predict mode makes the software program predict the position the position of the aircraft for how many scans?
15 scans
(844) to maintain synchronization with air route traffic control centers (ARTCC) equipment, an inter-facility communications adapter (ICA) at idle
transmits a pattern of ones and zeros continually until the start of the data
(844) If the operation program detects a data transmission error from an air route traffic control center (ARTCC), the
message is ignored
(845) Regarding the programmable indicator data processor (PIDP) tabular data, what area of the radar display shows the date, hour, minute, second, barometric pressure, and altitude filter limits (upper and lower)
operating parameters list
(846) When the system computer is disengaged, the OD-153 indicator operates as
a conventional plan position indicator (PPI)
(846) How many sectors of the input data represent 360 degrees of antenna rotation in the OD-153
[834] What subcomponent ensures time coincidence between Selective Identification Feature (SIF) video and radar video?
The coder-synchronizer
[834] What is considered the major output of the coder-synchronizer.
Mode Interrogation pulses (P1, P2, and P3)
[834] 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 AN/TPX-42 interrogator set.
[834] What is the function of the interference blanker?
It cancels nonsynchronous replies, commonly called FRUIT (Friendly Replies Unsynchronized In Time).
[835] How does the Range Azimuth Beacon Monitor (RABM) help you, the maintenance technician?
It provides a test target with known coordinates for system analysis.
[835] What characteristics of the Range Azimuth Beacon Monitor (RABM) restrict its use to within 3 miles of the radar site?
Its low power output and receiver sensitivity.
[835] What factors determine at what range the Range Azimuth Beacon Monitor (RABM) test target is displayed?
The total distance the RABM is remoted from the radar site and the setting of the range delay switches.
[835] How do we keep the Range Azimuth Beacon Monitor (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.
[835] How is the reciever protected during transmission of the Range Azimuth Beacon Monitor (RABM) reply?
The diplexer's precise cable lengths let it act as an isolator between the transmitter and the receiver channels.
[835] If the initial installation of the Range Azimuth Beacon Monitor (RABM) is three miles from the transmitter site, how much attenuation should be used first? Why?
Maximum attenuation (60 dB). This prevents the probability of damaging the receiver input circuits.
[835] What is the function of the Pulse Width Discriminator (PWD)?
It eliminates any signal less than 0.36 usec wide and standardizes the P1 and P3 pulses to 0.5 usec.
[835] What purpose does the mode latch serve?
It educates the encoder as to which mode of interrogation is being processed This ensures that the Range Azimuth Beacon Monitor (RABM) provides a valid reply for the received interrogation.
[835] What factors determine the reply code and the type of reply transmitted by the Range Azimuth Beacon Monitor (RABM)?
It is determined by the reply code switches and the mode of interrogation. The reply selector determines the type of reply transmitted.
[836] What conditions must be present for the trigger separator to provide the operational receiver/transmitter with challenge video?
The trigger separator must receive a challenge enable signal from the remote site and a range error enable signal from the pretrigger monitor/Interogator-Side-Lobe-Suppression (ISLS) switch driver.
[836] Receiver video is sent to what assembly from the channel select relay?
Interference blanker.
[836] What is the purpose of the RF switch and directional coupler?
They provide calibrated transmitter energy for Voltage Standing Wave Ratio (VSWR) measurements, route the on-line receiver transmitter energy to the Interrogator Side Lobe Suppression (ISLS) switch or diplexer, send receiver video back to the on-line receiver/transmitter, and connect the standby receiver/transmitter to the dummy load.
[836] When is the Interrogator Side Lobe Suppression (ISLS) switch used?
It's used on radars that have a capacitively coupled rotary joint and separate omni directional antenna.
[837] What is the purpose of the Gain Time Control (GTC) delay gate, and when is it produced?
It inhibits the receiver during transmission of mode interrogations. It's produced in the internal trigger mode only.
[837] At what frequency does the dielectric resonator oscillator (DRO) oscillate?
4120 MHz
[837] What is the effect on turning the GTC switch on?
It reduces the gain for reply code trains of close-in targets.
[837] What conditions must be met to illuminate the video monitor lamp?
There must be a raw video monitor pulse, interrogation pulses and a self-test gate.
[837] In video logic 1, what is the function of the Self Test Gate (STG)?
The leading edge of the STG clears each of the monitor circuits and enables the receiver test trigger generator. The gate itself is integrated to provide the DC voltage needed to operate the monitor circuits. The trailing edge of the gate resets the lamp circuits if the required monitor pulses are present.
[838] What is the purpose of the video signal processor?
It decodes the reply code video and checks for various special replies and conditions.
[838] What aircraft target information is stored in the Video Signal Processor (VSP) memory?
Mode identity, range, azimuth, and altitude.
[838] 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.
[838] What is the importance of bracket video?
It's the real-time video presentation coincident with last available live-time beacon signal. It's the radar target video, and it can be used in troubleshooting.
[838] Where is barometric pressure manually entered?
Master Indicator
[839] What is the function of the line-compensator assembly (LCA)?
It is used when AN/TPX-42 data is remoted via la land line. The LCA makes up for signal distortion and loss caused by a coaxial line. It uses a bridge-T compensating networks to compensate for signal distortion. An output amplifier is used to reestablish a 3:1 trigger-to-video ratio.
[839] How is random noise removed from the seperated video output of the trigger separator?
The signal is sent to two amplitude comparator circuits. The first comparator circuit passes only trigger inputs, which are sent as separated triggers to the trigger decode circuits. The other comparator circuit is set at a reference level above the random noise level but below the minimum video amplitude.
[839] What is the purpose of the trigger decode logic circuits?
They determine which interrogation mode is being processed.
[839] What is the purpose of the video signal processor?
It produces one target report message per antenna revolution for each responding aircraft within range.
[839] When does a true garble conditon exist?
It exists when the replies from two or more aircraft overlap and are synchronous.
[839] What subunit in the Video Signal Processor (VSP) performs quasi-defruiting and when does it occur?
The Targer Detection Unit (TDU);
Quasi-defruiting is performed when the interference blanker isn't operating or is in standby mode.
[840] What normally determines the power level at which the IR units are operated?
This level is normally established during an air traffic control and landing system (ATCLS) evaluation or prescribed in local Federal Aviation Administration (FAA) guidelines. Low power is almost always sufficient.
[840] What does it indicate if the TARGET LOAD indicator comes on?
It is indicating that the Indicator Data Processor (IDP) is processing more thatn 128 targets or the Programmable Indicator Data Processor (PIDP II) is processing more than 300 targets.
[841] What is meant by the term "tag" on the radar display?
A dynamic presentation of target data, affixed to all radar replies.
[841] List the contents of a maximum message tag.
A position symbol, leader, and a 4-line tag containing aircraft identification (flight number), reported beacon code, reported altitude, aircraft class, ground speed, and a controller commentary or system warning flags.
[841] List the contents of the tabular presentation of auxiliary data that's available for display.
The tabular type presentation of auxiliary data consits of operating parameter information, arrival/departure data, drop/suspend data, and preview data.
[841] 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.
[841] What is the advantage of having two operator keywords per control indicator group?
It lets one controller "work" active traffic and the other controller perform flight data entry/modification, handoffs, etc., as operational traffic loads dictate.
[841] List the three saftey monitoring features on the Programmable Indicator Data Processor (PDIP) II system.
Altitude monitoring, Minimum Safe Altitude Warning (MSAW), and conflict alert.
[842] What is the purpose of the NAS modem unit in the OL-475/T processor?
Exchanges handoffs, flight plans, departure, and test messages between the PDIP II and the FAA NAS en-route center.
[842] What allows communications between the system control console and the Programmable Display Processor (PDP)?
The use of BLAST emulation software.
[842] List the input signals to the PIDP II from the AN/TPX-42A beacon system.
(1) Frequency-shift keyed (FSK) data.
(2) Azimuth change pulses (ACPs).
(3) Azimuth reference pulse (ARP).
[842] What is the purpose of the keyboard at each indicator?
It controls the display of data at that indicator position.
[842] On the OD-153 display, what is used to change cursor bearing and position of the range strobe?
The Position Entry Module (PEM).
[842] What system component is used to initialize the PIDP II system?
The indicator designated as the master display.
[843] The low-altitude alerting system contains how many geographic sectors?
[843] 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.
[844] What is the purpose of the NAS modem?
It allows data exchange via telephone lines between the terminal (PIDP) and NAS en route (ARTCC) centers.
[844] Describe the NAS modem.
Full-duplex modem with a transmission rate of 2400 baud.
[844] How many displays can an interface card communicate with?
[844] When does data transmission happen between the CPU and the display interface?
During generation of a sector interrupt, which occurs every 11.25° from north (0°).
[845] What does the small circle symbol represent?
A non-selected target that isn't "tracked" by any other indicator.
[845] How many character lines may be displayed for a nonselected target?
2 lines.
[845] What is the symbol for a controlled tracked target?
The letter designator of the indicator tracking the target.
[845] What is the purpose of the preview area?
It displays the keyboard messages entered by the operator and permits editing of the data before entering it into the system.
[845] What is the maximum number of arrival/departures that may be displayed?
[845] Where are cursor and range strobe readouts displayed?
On line two of the operating parameter list.
[845] List the 3 special replies and their codes.
(1) Hijack (7500 beacon code)
(2) Communications failure (7600 beacon code)
(3) Emergency (7700 beacon code)
[846] At what rate must synthetic data be refreshed by the data processing circuit?
At a nominal 25-Hz rate.
[846] How many sectors are used to transfer PPI input data from the computer PPI to the display?
32 sectors that represent 360° of antenna rotation.

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