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51 Cards in this Set
- Front
- Back
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TACAN Navigational Set AN/ARN-118(V) is what type of navigation system?
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Polar coordinate navigation system
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What is the AN/ARN-118 used to determine? |
It is used to determine the relative bearing and/or slant-range distance to a TACAN ground station or cooperating aircraft |
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What information is supplied to the interrogating aircraft? |
Only distance data |
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What is the operating range limit of the TACAN system? |
Line-of-sight, and depends on aircraft altitude and type of terrain |
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How many channels are available for operation on the TACAN system?
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252
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How many channels are there in the X and Y mode?
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126
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Both the X and Y mode in the TACAN are spaced at________ intervals.
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1 MHz
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The TACAN channels provide airborne transmit (interrogation) frequencies from
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1025 to 1150 MHz
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The TACAN airborne receive frequencies are from
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962 to 1213 MHz
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The AN/ARN-118(V) operates in what ground-to-air modes?
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Receive (REC) Transmit-Receive (T/R) |
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The AN/ARN-118(V) operates in what air-to-air modes?
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Air-to-air transmit-receive (A/A T/R) Air-to-air receive (A/A REC) Self-test (in-flight confidence test) |
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What is required for operation of a TACAN system? |
A TACAN beacon, either surface or airborne |
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What is contained in a SURFACE BEACON signal?
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a. Distance reply pulse
b. North or main reference burst c. Auxiliary reference bursts d. 15-Hz variable coarse bearing signal e. 135-Hz variable fine bearing signal f. 1350-Hz station identification signal g. 2700-Hz fill or squitter pulses |
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How much of a separation is between the interrogation signal from an airborne TACAN system and the surface beacon transmit frequency?
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63 MHz
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The surface beacon consists of how many antennas? |
Two drum-type antennas to produce and transmit the complex signal |
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How fast do the surface beacon antennas rotate? |
900 r/min or 15 Hz |
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How many reflectors is the inner antenna equipped with and what radiation pattern is produced? |
One; cardioid (heart-shaped) radiation pattern |
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What frequency is produced by the inner drum antenna? |
15-Hz variable course bearing signal |
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How many reflectors is the outer antenna equipped with and what radiation pattern is produced? |
Nine; cardioid radiation pattern converts to a lobed radiation pattern with the lobes spaced 40 degrees apart |
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What signal is produced and transmitted by the outer drum antenna?
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135-Hz variable fine bearing signal |
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What produces the main and auxiliary bursts?
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A disk located under the rotating antenna |
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What does the main burst consist of? |
12 pulse pairs spaced at 30-μs intervals for X-channels :or can be 13 single pulses spaced at 30-μs intervals for Y-channels |
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When does the main burst occur? |
When the maximum antenna radiation is directed due east |
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When does the auxiliary burst occur? |
At 40-degree intervals after the main burst, this divides each antenna rotation into nine sectors |
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What does the auxiliary burst consist of? |
6 pulse pairs, each pair spaced at 24-μs for X-channels or 13 single pulses spaced at 15-μs intervals for Y-channels |
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How are the main reference burst and 15-Hz signal used? |
To isolate the bearing to a 40-degree sector |
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How are the auxiliary bursts and 135-Hz signal used? |
To determine the exact bearing within a 40-degree sector |
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How does a surface beacon act for distance measurements? |
As a transponder |
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How long after a surface beacon receives the interrogation from an airborne TACAN system does it take to reply? |
50μs; it transmits a distance reply pulse pair |
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Why does the reply pulse pair replace a random 2700-Hz squitter pulse pair? |
To prevent airborne TACAN systems from locking on to squitter pulses |
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When can the reply pulse pairs not occur? |
During a main or auxiliary burst or During the transmission of an identification signal letter |
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How are the pulses of the reply pulse pair spaced? |
12μs apart when X-channel is selected 30μs apart when Y-channel is selected |
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What does the airborne TACAN system measure using the distance reply pulses? |
Aircraft slant-range distance to the surface beacon |
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Station identification signals are a coded 3-letters decoded from what signal? |
The 1350-Hz double pulse pairs that replaced the squitter pulses at 30-second intervals |
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At what frequency are air-to-air mode bearing signals? |
15 Hz |
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What is the nominal delay time for the distance reply pulse to be produced? |
62-μs in X-channel 74-μs in Y-channel |
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What does the airborne TACAN system measure in the REC mode? |
The fundamental bearing of a selected TACAN surface beacon |
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What is fundamental bearing? |
The angle to the beacon referenced to magnetic north |
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What does the airborne TACAN system measure in the T/R mode? |
The fundamental bearing and calculates the relative bearing Also measures the slant-range distance to the selected TACAN surface beacon |
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What is the difference between REC mode and A/A REC mode operation? |
Operation is the same, except that the bearing data is received from a suitably equipped, cooperating aircraft (The 135-Hz bearing signal is inhibited since air-to-air bearing signals are 15-Hz only) |
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Why must the cooperating aircraft in A/A REC mode be contacted? |
To establish operating channels 63 channels apart before bearing and distance data can be obtained [The 63-channel (MHz) spacing simulates the spacing between transmit and receive frequencies when a surface beacon is used for bearing data] |
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The AN/ARN-118(V) cannot produce and transmit what data? |
Bearing data |
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What is transmitted when the AN/ARN-118(V) is interrogated? |
Distance data |
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How many types of self-tests does the TACAN system provide? |
2: Manual Self-Test (Confidence Test) Automatic Self-Test |
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During a manual self-test, pressing the TEST switch checks with circuits? |
Receive Distance Bearing |
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When does the TACAN system switch to an automatic self-test? |
When the signal from the surface beacon becomes unreliable or lost (memory time elapsed) |
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What is RNAV? |
Area Navigation |
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Computers in the RNAV system use what data produced by the airborne TACAN system? |
Ternary word distance Bearing Range |
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What modes of operation are selectable on the RT control? |
REC T/R A/A REC A/A T/R |
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What is the difference between A/A T/R mode and T/R? |
In A/A T/R mode the reply received from another aircraft is a single pulse distance reply |
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What is the spacing for pulses in the air-to-air mode of operation? |
12μs for X-channel 24μs for Y-channel |
