Ship RADAR Endorsement

Choose the most correct statement containing the parameters which control the size of the target echo.

Which of the following has NO effect on the maximum range capability?

What type of transmitter power is measured over a period of time?

What RADAR component controls timing throughout the system?

Which of the following components allows the use of a single antenna for both transmitting and receiving?

The sweep frequency of a RADAR indicator is determined by what parameter?

A radio wave will travel a distance of three nautical miles in:

One RADAR mile is how many microseconds?

RADAR range is measured by the constant:

If a target is 5 miles away, how long does it take for the RADAR echo to be received back at the antenna?

How long would it take for a RADAR pulse to travel to a target 10 nautical miles away and return to the RADAR receiver?

What is the distance in nautical miles to a target if it takes 308.5 microseconds for the RADAR pulse to travel from the RADAR antenna to the target and back.

Frequencies generally used for marine RADAR are in the ___ part of the radio spectrum.

Practical RADAR operation requires the use of microwave frequencies so that:

An S-band RADAR operates in which frequency band?

A RADAR operating at a frequency of 3 GHz has a wavelength of approximately:

The major advantage of an S-band RADAR over an X-band RADAR is:

An X band RADAR operates in which frequency band?

A pulse RADAR has a pulse repetition frequency (PRF) of 400 Hz, a pulse width of 1 microsecond, and a peak power of 100 kilowatts. The average power of the RADAR transmitter is:

A shipboard RADAR transmitter has a pulse repetition frequency (PRF) of 1,000 Hz, a pulse width of 0.5 microseconds, peak power of 150 KW, and a minimum range of 75 meters. Its duty cycle is:

A pulse RADAR transmits a 0.5 microsecond RF pulse with a peak power of 100 kilowatts every 1600 microseconds. This RADAR has:

If a RADAR transmitter has a pulse repetition frequency (PRF) of 900 Hz, a pulse width of 0.5 microseconds and a peak power of 15 kilowatts, what is its average power output?

What is the average power if the RADAR set has a PRF of 1000 Hz, a pulse width of 1 microsecond, and a peak power rating of 100 kilowatts?

A search RADAR has a pulse width of 1.0 microsecond, a pulse repetition frequency (PRF) of 900 Hz, and an average power of 18 watts. The unit’s peak power is:

For a range of 5 nautical miles, the RADAR pulse repetition frequency should be:

For a range of 100 nautical miles, the RADAR pulse repetition frequency should be:

The minimum range of a RADAR is determined by:

Short range RADARs would most likely transmit:

For a range of 30 nautical miles, the RADAR pulse repetition frequency should be:

For a range of 10 nautical miles, the RADAR pulse repetition frequency (PRF) should be:

If the PRF is 2500 Hz, what is the PRI?

If the pulse repetition frequency (PRF) is 2000 Hz, what is the pulse repetition interval (PRI)?

The pulse repetition rate (PRR) refers to:

If the RADAR unit has a pulse repetition frequency (PRF) of 2000 Hz and a pulse width of 0.05 microseconds, what is the duty cycle?

Small targets are best detected by:

What is the relationship between pulse repetition rate and pulse width?

What component of a RADAR receiver is represented by block 46 in Fig. 8A1?

A basic sample-and-hold circuit contains:

When comparing a TTL and a CMOS NAND gate:

Silicon crystals:

Which is typical current for a silicon crystal used in a RADAR mixer or detector circuit?

What component of a RADAR receiver is represented by block 47 in Fig. 8A1?

The basic frequency determining element in a Gunn oscillator is:

Which of the following is not a method of analog-to-digital conversion?

When comparing TTL and CMOS logic families, which of the following is true:

The primary operating frequency of a reflex klystron is controlled by the:

A Gunn diode oscillator takes advantage of what effect?

Fine adjustments of a reflex klystron are accomplished by:

Blocking oscillators operate on the formula of:

The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.

The phantastron circuit is capable of:

The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.

In the Line-Driver/Coax/Line-receiver circuit shown in Fig. 8A3, what component is represented by the blank box marked "X"?

Choose the most correct statement:

In the circuit shown in Fig. 8A4, U5 pins 1 and 4 are high and both are in the reset state. Assume one clock cycle occurs of Clk A followed by one cycle of Clk B. What are the output states of the two D-type flip flops?

If more light strikes the photodiode in Fig. 8A5, there will be:

In the circuit shown in Fig. 8A6, which of the following is true?

What is the correct value of RS in Fig. 8A7, if the voltage across the LED is 1.9 Volts with 5 Volts applied and If max equals 40 milliamps?

The block diagram of a typical RADAR system microprocessor is shown in Fig. 8A2. Choose the most correct statement regarding this system.

You are troubleshooting a component on a printed circuit board in a RADAR system while referencing the Truth Table in Fig. 8A8. What kind of integrated circuit is the component?

The magnetron is used to:

The purpose of the modulator is to:

Which of the following statements about most modern RADAR transmitter power supplies is false?

The purpose of the Pulse Forming Network is to:

The purpose of the Synchronizer is to:

Which of the following is not part of the transmitting system?

High voltage is applied to what element of the magnetron?

The characteristic of the magnetron output pulse that relates to accurate range measurement is its:

What device is used as a transmitter in a marine RADAR system?

The magnetron is:

A negative voltage is commonly applied to the magnetron cathode rather than a positive voltage to the magnetron anode because:

The anode of a magnetron is normally maintained at ground potential:

In a solid-state RADAR modulator, the duration of the transmitted pulse is determined by:

The modulation frequency of most RADAR systems is between:

A shipboard RADAR uses a PFN driving a magnetron cathode through a step-up transformer. This results in which type of modulation?

In a pulse modulated magnetron what device determines the shape and width of the pulse?

What device(s) may act as the modulator of a RADAR system?

The purpose of a modulator in the transmitter section of a RADAR is to:

The pulse developed by the modulator may have an amplitude greater than the supply voltage. This is possible by:

Pulse transformers and pulse-forming networks are commonly used to shape the microwave energy burst RADAR transmitter. The switching devices most often used in such pulse-forming circuits are:

The purpose of the pulse-forming network is to:

The shape and duration of the high-voltage pulse delivered to the magnetron is established by:

Pulse-forming networks are usually composed of the following:

An artificial transmission line is used for:

The ferrite material in a circulator is used as a(an):

In a circular resonant cavity with flat ends, the E-field and the H-field form with specific relationships. The:

A ferrite circulator is most commonly used in what portion of a RADAR system?

A circulator provides what function in the RF section of a RADAR system?

A directional coupler has an attenuation of -30 db. A measurement of 100 milliwatts at the coupler indicates the power of the line is:

What is the purpose or function of the RADAR duplexer/circulator?

The ATR box:

When a pulse RADAR is radiating, which elements in the TR box are energized?

The TR box:

What device is located between the magnetron and the mixer and prevents received signals from entering the magnetron?

A keep-alive voltage is applied to:

A DC keep-alive potential:

What RADAR circuit determines the pulse repetition rate (PRR)?

The triggering section is also known as the:

Operation of any RADAR system begins in the:

The timer circuit:

Pulse RADARs require precise timing for their operation. Which type circuit below might best be used to provide these accurate timing pulses?

Unblanking pulses are produced by the timer circuit. Where are they sent?

An advantage of resonant charging is that it:

The characteristics of a field-effect transistor (FET) used in a modern RADAR switching power supply can be compared as follows:

A pulse-width modulator in a switching power supply is used to:

In a fixed-frequency switching power supply, the pulse width of the switching circuit will increase when:

A major consideration for the use of a switching regulator power supply over a linear regulator is:

Which of the following characteristics are true of a power MOSFET used in a RADAR switching supply?

Which of the following statements is true?

Logarithmic receivers:

RADAR receivers are similar to:

What section of the receiving system sends signals to the display system?

What is the main difference between an analog and a digital receiver?

In a RADAR receiver, the RF power amplifier:

The diagram in Fig. 8C9 shows a simplified RADAR mixer circuit using a crystal diode as the first detector. What is the output of the circuit when no echoes are being received?

In the receive mode, frequency conversion is generally accomplished by a:

An RF mixer has what purpose in a RADAR system?

In a RADAR unit, the mixer uses a:

What component of a RADAR receiver is represented by block 49 in Fig. 8A1?

In a RADAR unit, the mixer uses:

The error voltage from the discriminator is applied to the:

In a RADAR unit, the local oscillator is a:

What component of a RADAR receiver is represented by block 48 in Fig. 8A1?

What device(s) could be used as the local oscillator in a RADAR receiver?

The klystron local oscillator is constantly kept on frequency by:

How may the frequency of the klystron be varied?

Overcoupling in a RADAR receiver will cause?

The usual intermediate frequency of a shipboard RADAR unit is:

The I.F. Amplifier bandwidth is:

A logarithmic IF amplifier is preferable to a linear IF amplifier in a RADAR receiver because it:

The high-gain IF amplifiers in a RADAR receiver may amplify a 2 microvolt input signal to an output level of 2 volts. This amount of amplification represents a gain of:

In a RADAR receiver AGC and IAGC can vary between:

Which of the following statements is correct?

Video amplifiers in pulse RADAR receivers must have a broad bandwidth because:

In video amplifiers, compensation for the input and output stage capacitances must be accomplished to prevent distorting the video pulses. This compensation is normally accomplished by connecting:

Which of the following signals is not usually an input to the video amplifier?

Which of the following signals are usually an input to the video amplifier?

The video (second) detector in a pulse modulated RADAR system would most likely use a/an:

The AFC system is used to:

A circuit used to develop AFC voltage in a RADAR receiver is called the:

In the AFC system, the discriminator compares the frequencies of the:

An AFC system keeps the receiver tuned to the transmitted signal by varying the frequency of the:

A RADAR transmitter is operating on 3.0 GHz and the reflex klystron local oscillator, operating at 3.060 GHz, develops a 60 MHz IF. If the magnetron drifts higher in frequency, the AFC system must cause the klystron repeller plate to become:

What component is block 50 in Fig. 8A1?

The STC circuit is used to:

The STC circuit:

Sea return is:

Sea clutter on the RADAR scope cannot be effectively reduced using front panel controls. What circuit would you suspect is faulty?

What circuit controls the suppression of sea clutter?

The sensitivity time control (STC) circuit:

Prior to making “power-on” measurements on a switching power supply, you should be familiar with the supply because of the following:

A constant frequency switching power supply regulator with an input voltage of 165 volts DC, and a switching frequency of 20 kHz, has an “ON” time of 27 microseconds when supplying 1 ampere to its load. What is the output voltage across the load?

The circuit shown in Fig. 8C10 is the output of a switching power supply. Measuring from the junction of CR6, CR7 and L1 to ground with an oscilloscope, what waveform would you expect to see?

With regard to the comparator shown in Fig. 8C11, the input is a sinusoid. Nominal high level output of the comparator is 4.5 volts. Choose the most correct statement regarding the input and output.

When monitoring the gate voltage of a power MOSFET in the switching power supply of a modern RADAR, you would expect to see the gate voltage change from “low” to “high” by how much?

The nominal output high of the comparator shown in Fig. 8C11 is 4.5 volts. Choose the most correct statement which describes the trip points.

One of the best methods of reducing noise in a RADAR receiver is?

The primary cause of noise in a RADAR receiver can be attributed to:

Noise can appear on the LCD as:

RADAR interference on a communications receiver appears as:

In a RADAR receiver the most common types of interference are?

Noise can:

The purpose of the discriminator circuit in a RADAR set is to:

The MTI circuit:

Where is a RF attenuator used in a RADAR unit?

The condition known as “glint” refers to a shifting of clutter with each RADAR pulse and can be caused by a:

An ion discharge (TR) cell is used to:

When the receiver employs an MTI circuit:

Modern liquid crystal displays have a pixel count of:

Voltages used in CRT anode circuits are in what range of value?

The purpose of the aquadag coating on the CRT is:

LCD patterns are formed when:

In a raster-type display, the electron beam is scanned:

Select the statement, which is most correct regarding a raster scan display.

What are the usual input signals to the video amplifier?

Which of the following would not normally be an input to the video amplifier?

The purpose of the sweep amplifier is to:

How many deflection coils are driven by the sweep amplifier?

The main purpose of the sweep generator is to provide:

The main purpose of the video amplifier is to provide:

Timing circuits are used to provide what function?

The circuit that develops timing signals is called the:

Which of the following functions is not affected by the timing circuit?

The synchronizer primarily affects the following circuit or function:

The output from the synchronizer usually consists of a:

The sweep drive is initiated by what circuit?

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:

Range markers are determined by:

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:

What would be the frequency of a range ring marker oscillator generating range rings at 10 nautical miles intervals?

What is the distance between range markers if the controlling oscillator is operating at 20 kHz?

What would be the frequency of a range ring marker oscillator generating range rings at intervals of 0.25 nautical miles?

The variable range marker signal is normally fed to the input of the:

The purpose of the variable range marker is to:

How is the variable range marker usually adjusted for accuracy?

The panel control for the variable range marker is normally a:

An important component of the VRM system is the:

Which of the following statements about the Variable Range Marker system is correct?

The purpose of the Electronic Bearing Line is to:

The Electronic Bearing Line is:

Which of the following inputs is required to indicate azimuth?

Bearing information from the gyro is used to provide the following:

Which of the following statements about “true bearing” is correct?

A true bearing presentation appears as follows:

In a digitized RADAR, the 360 degree sweep is divided into how many digitized segments?

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?

The term DRAM stands for:

How does the dual memory function reduce sea clutter?

How many sequential memory cells with target returns are required to display the target?

What is the primary purpose of display system memory?

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?

What does the term ARPA/CAS refer to?

Which of the following would not be considered an input to the computer of a collision avoidance system?

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.

What is the purpose or function of the “Trial Mode” used in most ARPA equipment?

The ARPA term CPA refers to:

The display power supply provides the following:

The display power supply provides the following:

In a display system power supply what is the purpose of the chopper?

In a display system power supply, what is the purpose of the inverter?

What would be a common switching frequency for a display system power supply?

What display system power supply output would use a tripler circuit?

The heading flash is a momentary intensification of the sweep line on the PPI presentation. Its function is to:

The major advantage of digitally processing a RADAR signal is:

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:

Bearing resolution is:

The output of an RC integrator, when driven by a square wave with a period of much less than one time constant is a:

How do you eliminate stationary objects such as trees, buildings, bridges, etc., from the PPI presentation?

Slotted waveguide arrays, when fed from one end exhibit:

A typical shipboard RADAR antenna is a:

Good bearing resolution largely depends upon:

The center of the transmitted lobe from a slotted waveguide array is:

How does antenna length affect the horizontal beamwidth of the transmitted signal?

What is the most common type of RADAR antenna used aboard commercial maritime vessels?

The VSWR of a microwave transmission line device might be measured using:

The impedance total (ZO) of a transmission line can be calculated by ZO = √L/C when L and C are known. When a section of transmission line contains 250 microhenries of L and 1000 picofarads of C, its impedance total (ZO) will be:

If long-length transmission lines are not properly shielded and terminated:

A certain length of transmission line has a characteristic impedance of 72 ohms. If the line is cut at its center, each half of the transmission line will have a ZO of:

Standing waves on a transmission line may be an indication that:

What precautions should be taken with horizontal waveguide runs?

The position of the PPI scope sweep must indicate the position of the antenna. The sweep and antenna positions are frequently kept in synchronization by the use of:

On a basic synchro system, the angular information is carried on the:

What is the most common type of antenna position indicating device used in modern RADARs?

Which of the following statements about antenna resolvers is correct?

An antenna synchro transmitter is composed of the following:

RADAR antenna direction must be sent to the display in all ARPAs or RADAR systems. How is this accomplished?

Waveguides can be constructed from:

A microwave transmission line constructed of a center conductor suspended between parallel conductive ground planes is called:

Waveguide theory is based upon:

A waveguide is used at RADAR microwave frequencies because:

Waveguide theory is based on the principals of:

How is the signal removed from a waveguide or magnetron?

A rotary joint is used to:

Resistive losses in a waveguide are very small because:

A right-angle bend in an X-band waveguide must have a radius greater than:

To insert RF energy into or extract RF energy from a waveguide, which of the following would not be used?

The following is true concerning waveguides:

At microwave frequencies, waveguides are used instead of conventional coaxial transmission lines because:

When you examine the RADAR you notice that there is no target video in the center of the CRT. The blank spot gets smaller in diameter as you increase the range scale. What operator front panel control could be misadjusted?

Range rings on the PPI indicator are oval in shape. Which circuit would you suspect is faulty?

What would be the most likely defective area when there is no target video in the center of the CRT and the blank spot gets smaller in diameter as your range scale is increased?

While the vessel is docked the presentation of the pier is distorted near the center of the PPI with the pier appearing to bend in a concave fashion. This is a primary indication of what?

In a RADAR using digital video processing, a bright, wide ring appears at a fixed distance from the center of the display on all digital ranges. The transmitter is operating normally. What receiver circuit would you suspect is causing the problem?

The raster scan RADAR display has missing video in a rectangular block on the screen. Where is the most likely problem area?

A circuit card in a RADAR system has just been replaced with a spare card. You notice the voltage level at point E in Fig. 8F12 is negative 4.75 volts when the inputs are all at 5 volts. The problem is:

A defective crystal in the AFC section will cause:

The RADAR display has sectors of solid video (spoking). What would be the first thing to check?

In the circuit contained in Fig. 8F12, there are 5 volts present at points B and C, and there are zero volts present at points A and D. What is the voltage at point E?

If the TR tube malfunctions:

The indicated distance from your own vessel to a lighthouse is found to be in error. What circuit would you suspect?

Silicon crystals are used in RADAR mixer and detector stages. Using an ohmmeter, how might a crystal be checked to determine if it is functional?

In a RADAR unit, if the crystal mixer becomes defective, replace the:

An increase in magnetron current that coincides with a decrease in power output is an indication of what?

It is reported that the RADAR is not receiving small targets. The most likely causes are:

A high magnetron current indicates a/an:

Low or no mixer current could be caused by:

If the magnetron is allowed to operate without the magnetic field in place:

Targets displayed on the RADAR display are not on the same bearing as their visual bearing. What should you first suspect?

Loss of distant targets during and immediately after wet weather indicates:

In a marine RADAR set, a high VSWR is indicated at the magnetron output. The waveguide and rotary joint appear to be functioning properly. What component may be malfunctioning?

On a vessel with two RADARs, one has a different range indication on a specific target than the other. How would you determine which RADAR is incorrect?

An increase in the deflection on the magnetron current meter could likely be caused by:

A thick layer of rust and corrosion on the surface of the parabolic dish will have what effect?

The echo box is used for:

What should be done to the interior surface of a waveguide in order to minimize signal loss?

Which of the following is the most useful instrument for RADAR servicing?

A non-magnetic screwdriver should always be used when replacing what component?

What kind of display would indicate water in the waveguide?

Why is coaxial cable often used for S-band installations instead of a waveguide?

RADAR interference to a communications receiver is eliminated by:

Why should long horizontal runs of waveguide be avoided?

Long horizontal sections of waveguides are not desirable because:

In a RADAR system, waveguides should be installed:

What is the most important factor to consider in locating the antenna?

Choose the most correct statement with respect to component damage from electrostatic discharge:

Before testing a RADAR transmitter, it would be a good idea to:

While making repairs or adjustments to RADAR units:

While removing a CRT from its operating casing, it is a good idea to:

If a CRT is dropped:

Prior to removing, servicing or making measurements on any solid state circuit boards from the RADAR set, the operator should ensure that: