All 60 FCC GROL questions for 8D Display & Control Systems with the correct answers marked, from the official current FCC question pool. Test yourself with the free practice exam.
8-29D1
Modern liquid crystal displays have a pixel count of:
A. Greater than 200 pixels per inch. ✓
B. Greater than 50 pixels per inch.
C. Can have no more than 125 pixels per inch.
D. Can implement 1,000 pixels per inch.
8-29D2
Voltages used in CRT anode circuits are in what range of value?
A. 0.5-10 mV.
B. 10-50 kV. ✓
C. 20-50 mV.
D. 200-1000 V.
8-29D3
The purpose of the aquadag coating on the CRT is:
A. To protect the electrons from strong electric fields.
B. To act as a second anode.
C. To attract secondary emissions from the CRT screen.
D. All of the above ✓
8-29D4
LCD patterns are formed when:
A. Current passes through the crystal causing them to align. ✓
B. When voltage is reduced to the raster scan display.
C. When the deflection coils are resonant.
D. When the ships antenna’s bearing is true North.
8-29D5
In a raster-type display, the electron beam is scanned:
A. From the center of the display to the outer edges.
B. Horizontally and vertically across the CRT face. ✓
C. In a rotating pattern which follows the antenna position.
D. From one specified X-Y coordinate to the next.
8-29D6
Select the statement, which is most correct regarding a raster scan display.
A. Raster displays are the same as conventional T.V. receivers.
B. The scan rate for a RADAR system is 30 frames per second.
C. Raster scanning is controlled by clock pulses and requires an address bus. ✓
D. Raster scanning is not used in RADAR systems.
8-30D1
What are the usual input signals to the video amplifier?
A. Low level video.
B. Fixed range rings.
C. Variable range rings.
D. All of the above. ✓
8-30D2
Which of the following would not normally be an input to the video amplifier?
A. Fixed range rings.
B. Variable range rings.
C. Resolver signal. ✓
D. Low level video.
8-30D3
The purpose of the sweep amplifier is to:
A. Increase the power of the video amplifier.
B. Drive the CRT deflection coils. ✓
C. Drive the resolver coils.
D. All of the above.
8-30D4
How many deflection coils are driven by the sweep amplifier?
A. 4
B. 3
C. 2 ✓
D. 1
8-30D5
The main purpose of the sweep generator is to provide:
A. Antenna information.
B. Range rings.
C. Composite video to the cathode of the CRT.
D. The drive signal to the sweep amplifier. ✓
8-30D6
The main purpose of the video amplifier is to provide:
A. Composite video to the cathode of the CRT. ✓
B. Resolver signals
C. Antenna X and Y signals.
D. Provide the drive signal to the sweep amplifier.
8-31D1
Timing circuits are used to provide what function?
A. Develop synchronizing pulses for the transmitter system. ✓
B. Synchronize the antenna and display system.
C. Adjust the sea return.
D. Control the North Up presentation.
8-31D2
The circuit that develops timing signals is called the:
A. Resolver.
B. Synchronizer. ✓
C. Pulse forming network.
D. Video amplifier.
8-31D3
Which of the following functions is not affected by the timing circuit?
A. Resolver output. ✓
B. Pulse repetition frequency.
C. Sweep drive.
D. Modulation.
8-31D4
The synchronizer primarily affects the following circuit or function:
A. Mixer.
B. Receiver.
C. Modulator. ✓
D. I.F. Amplifier.
8-31D5
The output from the synchronizer usually consists of a:
A. Sine wave.
B. Pulse or square wave. ✓
C. Triangle wave.
D. None of the above.
8-31D6
The sweep drive is initiated by what circuit?
A. Resolver.
B. Sweep amplifier.
C. Video amplifier.
D. Synchronizer. ✓
8-32D1
Accurate range markers must be developed using very narrow pulses. A circuit that could be used to provide these high-quality pulses for the CRT is a:
A. Ringing oscillator.
B. Monostable multivibrator.
C. Triggered bi-stable multivibrator.
D. Blocking oscillator. ✓
8-32D2
Range markers are determined by:
A. The CRT.
B. The magnetron.
C. The timer. ✓
D. The video amplifier.
8-32D3
A gated LC oscillator, operating at 27 kHz, is being used to develop range markers. If each cycle is converted to a range mark, the range between markers will be:
A. 3 nautical miles. ✓
B. 6 nautical miles.
C. 8 nautical miles.
D. 12 nautical miles.
8-32D4
What would be the frequency of a range ring marker oscillator generating range rings at 10 nautical miles intervals?
A. 24 kHz
B. 16 kHz
C. 12 kHz
D. 8 kHz ✓
8-32D5
What is the distance between range markers if the controlling oscillator is operating at 20 kHz?
A. 1 nautical miles.
B. 2 nautical miles.
C. 4 nautical miles. ✓
D. 8 nautical miles.
8-32D6
What would be the frequency of a range ring marker oscillator generating range rings at intervals of 0.25 nautical miles?
A. 161 kHz
B. 322 kHz ✓
C. 644 kHz
D. 1288 kHz
8-33D1
The variable range marker signal is normally fed to the input of the:
A. Sweep amplifier.
B. Low voltage power supply regulator.
C. Video amplifier. ✓
D. Range ring oscillator.
8-33D2
The purpose of the variable range marker is to:
A. Provide an accurate means of determining the range of a moving target. ✓
B. Provide a bearing line between own ship and a moving target.
C. Indicate the distance between two different targets.
D. Provide a means of calibrating the fixed range rings.
8-33D3
How is the variable range marker usually adjusted for accuracy?
A. Adjusting the frequency of the VRM oscillator at the maximum range.
B. Adjusting the frequency of the VRM oscillator at the minimum range.
C. Adjusting the readout to match at the median range ring.
D. The minimum and maximum ranges are aligned with the matching fixed range ring. ✓
8-33D4
The panel control for the variable range marker is normally a:
A. Variable resistor. ✓
B. Variable inductance.
C. Variable capacitance.
D. Variable resolver.
8-33D5
An important component of the VRM system is the:
A. Resolver.
B. Interference rejection circuit.
C. STC sensitivity control.
D. Shift register. ✓
8-33D6
Which of the following statements about the Variable Range Marker system is correct?
A. The VRM is an auxiliary output of the fixed range marker oscillator.
B. The VRM system develops a single adjustable range ring. ✓
C. The VRM system is calibrated using a frequency counter.
D. The VRM system is controlled by a crystal oscillator.
8-34D1
The purpose of the Electronic Bearing Line is to:
A. Indicate your own vessel’s heading.
B. Measure the bearing of a specific target. ✓
C. Indicate True North.
D. Display the range of a specific target.
8-34D2
The Electronic Bearing Line is:
A. The ships heading line.
B. A line indicating True North.
C. Used to mark a target to obtain the distance.
D. A line from your own vessel to a specific target. ✓
8-34D3
Which of the following inputs is required to indicate azimuth?
A. Gyro signals. ✓
B. Synchronizer
C. Resolver.
D. Range rings.
8-34D4
Bearing information from the gyro is used to provide the following:
A. The heading of the nearest target.
B. Range and bearing to the nearest target.
C. Vessel’s own heading. ✓
D. The range of a selected target.
8-34D5
Which of the following statements about “true bearing” is correct?
A. The ship’s heading flasher is at the top of the screen.
B. True North is at the top of the screen and the heading flasher indicates the vessel’s course. ✓
C. The true bearing of the nearest target is indicated.
D. The relative bearing of the nearest target is indicated.
8-34D6
A true bearing presentation appears as follows:
A. The bow of the vessel always points up.
B. The course of the five closest targets is displayed.
C. North is at the top of the display and the ship’s heading flasher indicates the vessel’s course. ✓
D. The course and distance of the closest target is displayed.
8-35D1
In a digitized RADAR, the 360 degree sweep is divided into how many digitized segments?
A. 16
B. 64
C. 255
D. 4,096 ✓
8-35D2
While troubleshooting a memory problem in a raster scan RADAR, you discover that the “REFRESH” cycle is not operating correctly. What type of memory circuit are you working on?
A. SRAM
B. DRAM ✓
C. ROM
D. PROM
8-35D3
The term DRAM stands for:
A. Digital refresh access memory.
B. Digital recording access memory.
C. Dynamic random access memory. ✓
D. Digital response area motion.
8-35D4
How does the dual memory function reduce sea clutter?
A. Successive sweeps are digitized and compared. Only signals appearing in both sweeps are displayed. ✓
B. The dual memory system makes the desired targets larger.
C. It reduces receiver gain for closer signals.
D. It increases receiver gain for real targets.
8-35D5
How many sequential memory cells with target returns are required to display the target?
A. 1
B. 2 ✓
C. 4
D. 8
8-35D6
What is the primary purpose of display system memory?
A. Eliminate fluctuating targets such as sea return. ✓
B. Display stationary targets.
C. Display the last available targets prior to a power dropout.
D. Store target bearings.
8-36D1
The ship’s speed indication on the ARPA display can be set manually, but does not change with changes in the vessel’s speed. What other indication would point to a related equipment failure?
A. “GYRO OUT” is displayed on the ARPA indicator.
B. “LOG OUT” is displayed on the ARPA indicator. ✓
C. “TARGET LOST” is displayed on the ARPA indicator.
D. “NORTH UP” is displayed on the ARPA indicator.
8-36D2
What does the term ARPA/CAS refer to?
A. The basic RADAR system in operation.
B. The device which displays the optional U.S.C.G. Acquisition and Search RADAR information on a CRT display.
C. The device which acquires and tracks targets that are displayed on the RADAR indicator’s CRT. ✓
D. The device which allows the ship to automatically steer around potential hazards.
8-36D3
Which of the following would not be considered an input to the computer of a collision avoidance system?
A. Own ship’s exact position from navigation satellite receiver.
B. Own ship’s gyrocompass heading.
C. Own ship’s speed from Doppler log.
D. Own ship’s wind velocity from an anemometer. ✓
8-36D4
Which answer best describes a line on the display which indicates a target’s position. The speed is shown by the length of the line and the course by the direction of the line.
A. Vector. ✓
B. Electronic Bearing Line.
C. Range Marker.
D. Heading Marker.
8-36D5
What is the purpose or function of the “Trial Mode” used in most ARPA equipment?
A. It selects trial dots for targets’ recent past positions.
B. It is used to display target position and your own ship’s data such as TCPA, CPA, etc.
C. It is used to allow results of proposed maneuvers to be assessed. ✓
D. None of these.
8-36D6
The ARPA term CPA refers to:
A. The furthest point a ship or target will get to your own ship’s bow.
B. Direction of target relative to your own ship’s direction.
C. The combined detection and processing of targets.
D. The closest point a ship or target will approach your own ship. ✓
8-37D1
The display power supply provides the following:
A. +18 volts DC for the pulse forming network.
B. 5 volts DC for logic circuits and 12 volts DC for analog and sweep circuits. ✓
C. 80 volts AC for the antenna resolver circuits.
D. All of the above
8-37D2
The display power supply provides the following:
A. 5 volts DC for logic circuits.
B. 12 volts DC for analog and sweep circuits.
C. 17kV DC for the CRT HV anode.
D. All of the above ✓
8-37D3
In a display system power supply what is the purpose of the chopper?
A. It acts as an electronic switch between the raw DC output and the inverter. ✓
B. It interrupts the AC supply line at a varying rate depending on the load demands.
C. It regulates the 5 volt DC output.
D. It pre-regulates the AC input.
8-37D4
In a display system power supply, what is the purpose of the inverter?
A. Inverts the polarity of the DC voltage applied to the voltage regulators.
B. Provides the dual polarity 12 volt DC supply.
C. Acts as the voltage regulator for the 5 volt DC supply.
D. Produces the pulsed DC input voltage to the power transformer. ✓
8-37D5
What would be a common switching frequency for a display system power supply?
A. 18 kHz ✓
B. 120 Hz
C. 60 kHz
D. 120 kHz
8-37D6
What display system power supply output would use a tripler circuit?
A. The logic circuit supply.
B. The sweep circuit supply.
C. The HV supply for the CRT anode. ✓
D. The resolver drive
8-38D1
The heading flash is a momentary intensification of the sweep line on the PPI presentation. Its function is to:
A. Alert the operator when a target is within range.
B. Alert the operator when shallow water is near.
C. Inform the operator of the dead-ahead position on the PPI scope. ✓
D. Inform the operator when the antenna is pointed to the rear of the ship.
8-38D2
The major advantage of digitally processing a RADAR signal is:
A. Digital readouts appear on the RADAR display.
B. Enhancement of weak target returns. ✓
C. An improved operator interface.
D. Rectangular display geometry is far easier to read on the CRT.
8-38D3
In order to ensure that a practical filter is able to remove undesired components from the output of an analog-to-digital converter, the sampling frequency should be:
A. The same as the lowest component of the analog frequency.
B. Two times the highest component of the analog frequency.
C. Greater than two times the highest component of the sampled frequency. ✓
D. The same as the highest component of the sampled frequency.
8-38D4
Bearing resolution is:
A. The ability to distinguish two adjacent targets of equal distance. ✓
B. The ability to distinguish two targets of different distances.
C. The ability to distinguish two targets of different elevations.
D. The ability to distinguish two targets of different size.
8-38D5
The output of an RC integrator, when driven by a square wave with a period of much less than one time constant is a:
A. Sawtooth wave.
B. Sine wave.
C. Series of narrow spikes.
D. Triangle wave. ✓
8-38D6
How do you eliminate stationary objects such as trees, buildings, bridges, etc., from the PPI presentation?
A. Remove the discriminator from the unit.
B. Use a discriminator as a second detector. ✓
C. Calibrate the IF circuit.
D. Calibrate the local oscillator.