GROL Element 3: Complete Study Guide and Practice Questions for General Radiotelephone Operator License

GROL Element 3: Complete Study Guide and Practice Questions for General Radiotelephone Operator License The product of the readings of an AC voltmeter and AC ammeter is called: Apparent power What is the term used to express the amount electrical energy stored in an electrostatic field? Joules What formula would determine the inductive reactance of a coil if frequency and coil inductance is known? Xl=2pi(fL) What determines the strength of a magnetic field around a conductor? The amount of current What will produce a magnetic field? A current flowing through a conductor. When induced currents produce expanding magnetic fields around conductors in a direction that opposes the original magnetic field, this is known as: Lenz's law Permeability is defined as? The ratio of magnetic flux density in a substance to the magnetizing force that produces it. What metal is usually employed as a sacrificial anode for corrosion control purposes? Zinc bar Which metal object may be least affected by galvanic corrosion when submerged in seawater? Stainless steel propeller shaft Skin effect is the phenomenon where: RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases. Which of these will be most useful for insulation at UHF frequencies? Mica What formula would calculate the total inductance of inductors in series? Lt=L1+L2 Which of the 4 group of metals are the best low-resistance conductors? Gold, silver, copper What is the purpose of a bypass capacitor? It removes the alternating current by providing a low impedance path to ground. What are the two most commonly-used specifications for a junction diode? Maximum forward current and peak inverse voltage (PIV) MOSFETs are manufactured with this protective device built into their gate to protect the device from static charges and excessive voltages: Zenner diode What are the two basic types of junction field-effect transistors? N-channel and P channel By what factor must the voltage of an AC circuit, as indicated on the scale of an AC voltmeter, be multiplied to obtain the peak voltage value? 1.414 What is the easiest voltage amplitude to measure by viewing a pure sine wave signal on an oscilloscope? Peak-to-peak What is the peak voltage at a common household electrical outlet? 165.5 volts What is a sine wave? A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating at a uniform speed. What type of wave is made up of sine waves of a fundamental frequency and all the odd frequencies? Square wave What type of wave is characterized by a rise time significantly faster then the fall time? Sawtooth wave What is the term used to identify an AC voltage that would cause the same heating in a resistor as a corresponding value of DC voltage? Root mean square (RMS) What happens to reactive power in a circuit that haw both inductors and capacitors? It alternates between magnetic and electric fields and is not dissipated Halving the cross-sectional area of a conductor will? Double the resistance Which of the following Ohms Law formulas is incorrect E=IxR If a current of 2 amperes flows through a 50-ohm resistor, what is the voltage across the resistor? 100 volts. Amps x Ohms = Volts A relay coil has 500 ohms resistance, and operates on 125 mA. What value of resistance should be connected in series with it to operate from 110 V DC? 380 ohms. 1step- V/I=R <=> 880-500=380 What is the peak-to-peak RF voltage on the 50 ohms output of a 100 watt transmitter? 200 volts. E=√(PxR) <=> 70.71v RMS <=> 100v one peak x 2 = 200v What is the maximum DC or RMS voltage that may be connected across a 20 watt, 2000 ohms resistor? 200 volts. E=√(PxR) <=> √(40,000) = 200v What is the voltage drop across R1 9v. Source volt - Zenner volt = 9v What is the most the actual transmit frequency could differ from a reading of 462,100,000 Hz on a frequency counter with a time base of ± 0.1ppm? 46.21 Hz What is the second harmonic of SSB frequency 4146 kHz? 8,292 What is the most the actual transmitter frequency could differ from a reading of 156,520,000 Hz on a frequency counter with a time base accuracy of ± 10ppm? 1,565.20 Hz At π/3 radians, what is the amplitude of a sine-wave having a peak value of 5 volts? 4.3v. V=(peak v) x sin(phase angle) <=> 5 x .866 At 150 degrees, what is the amplitude of a sine-wave having a peak value of 5 volts? 2.5v. V=(peak v) x sin(phase angle) <=> 5 x .5 What is the equivalent to the to the root-mean-square of an AC voltage? The DC voltage causing the same heating in a given resistor as the RMS AC voltage of the same value. What is the power factor equal in an R-L circuit having a 60 degree phase angle between the voltage and the current? .5 Power Factor=cos(phase angle) If a resistance to which a constant voltage is applied is halved, what power dissipation will result? Double What does the power factor equal in an R-L circuit having a 30 degree phase angle between the voltage and the current. .866 Power Factor=cos(phase angle) What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the supply voltage? One time constant What is the term for the time required for the capacitor in an RC circuit to build up to 63.2% of the maximum value One time constant After 2 time constants, the capacitor in an RC circuit is charged to what % or the starting voltage? 86.5% What is the time constant of a circuit having two 220-microfarad capacitors and two 1 megaohm resistors all in parallel? 220 sec. Resistance total = (1mil x 1mil)/(1mil + 1mil)=500k. Capacitance total = (220uF + 220uF)=440uF <=> 500k x 440uF = 220sec What is the time constant of a circuit having a one 100 microfarad capacitor and one 470 kilohm resistor in series? 47 sec. .000100 x 470,000=47 What is the time constant of a circuit having two 220 microfarad capacitors and two 1 megohm resistors all in series? 220 sec. Resistance total = (1meg + 1meg)=2megohms. Capacitance total = (220uF x 220uF) / (220uF + 220uF)= 48,400/440 =110uF <=> 2megohms x 110uF = 220sec What is the impedance of a network of a 0.1 microhenry inductor in a series with a 20 ohm resistor, at 30 MHz? Specify in rectangular coordinates! Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xₗ=2πfL 20+j19. Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xₗ=2πfL (2 × 3.14 × 30,000,000 × 0.0000001 = 18.84≈19). Rectangular coordinates : (inductive circuit) Z=R+jXₗ. (capacitive circuit) Z=-jXc In rectangular coordinates, what is the impedance of a network of a 10 microhenry inductor in series with a 40 ohms resistor, at 500 MHz? Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xₗ=2πfL 40+j31,400. Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xₗ=2πfL (2 × 3.14 × 500,000,000 × 0.00001 = 31,400). (inductive circuit) Z=R+jXₗ. (capacitive circuit) Z=R-jXc In rectangular coordinates, what is the impedance of a network composed of a .01 microfarad capacitor in parallel with a 300 ohm resistor, at 50 KHz ? Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xc=1/2πfC 159-j150. Reactance (Xc or Xₗ ) + resistance (R) = Impedance (Z) Z=√(R²+X²). Inductive reactance - Xc=1/2πfC ( (inductive circuit) Z=R+jXₗ. (capacitive circuit) Z=-jXc NOT COMPLETE In polar coordinates, what is the impedance of a network composed of a 100 ohm reactance inductor in series with a 100 ohm resistor? 141.4∠45 degrees. Z=√(R²+(L&C)²)∠(Arctan L,C/R) -> √(100²+100²)∠Arctan 1 -> √20,000∠45degrees -> 141.4∠45degrees. Anytime reactance and resistance is same, the phase ∠ is 45 degrees. In polar coordinates, what is the impedance of a network composed of a 400 ohm reactance capacitor in series with a 300 ohm resistor? 500∠-53.1 degrees. Z=√(R²+(L&C)²)∠(Arctan L,C/R) -> √(300²+400²)∠Arctan 1.3 -> √250,000∠-53.1 degrees -> 500∠-53.1 degrees. When in series the total resistance is greater then the given resistance. Using the polar coordinate system, what visual representation would you get of a voltage in a sinewave circuit? The magnitude and phase angle What is the magnitude of the impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance? 18Ω. Z=√(R²+(L&C)²) -> √(325) A 1 watt, 10 volt Zener diode with the following characteristics I(min)=5mA; I(max)=95mA; and Z=8ohms, is to be used part of a voltage regulator in a 20v power supply. Approximately what size current-limiting resistor would be used to set its bias to the midpoint its operating range? 200Ω. (I max + I min)/2 ->50mA -> 10v=.05A x R -> R=200Ω What is the conductance (G) of a circuit if 6 amps of current flow when 12 volts DC is applied? Answer is Siemens (mhos). .50 Siemens (mhos). I/E -> 6/12= .5 or 1/R -> V/I=R -> 12/6=2Ω -> 1/2 =.5 What is a photoconductive effect? The increased conductivity of an illuminated semiconductor junction. What is the description of an optoisolator? An LED and a photosensitive device. What is the description of an optocoupler? An LED and a photosensitive device. What factors determine the capacitance of a capacitor? Distance between the plates and the dielectric constant of the material between the plates. If a small variable capacitor were installed in place of a dashed line, it would? Decrease parasitic oscillations Which component (labeled 1 through 4) is used to provide a signal to ground? 2 What is the purpose of the coupling capacitor? It blocks direct current and passes alternating current. A transformer primary of 2250 turns connected to 120 VAC will develop what voltage across a 500-turn secondary? 26.7v. Volt(out)= 120 x (500/2250) What is the ratio of the output frequency to the input frequency of a single-phase full-wave rectifier? 2:1 We have an expert-written solution to this problem! A power transformer has a single primary winding and three secondary windings producing 5.0 v, 12.6 v and 150 v. Assuming similar wire sizes, which of the three secondary windings will have the highest measured DC resistance? 150v In a linear electronic voltage regulator: The conduction of a control element is varied in direct proportion to the line voltage or load current. 3 multiple choice options A switching electronic voltage regulator? Switches the control device on or off, with the duty cycle proportional to the line or load conditions. What device is usually used as a stable reference voltage in a linear voltage regulator? Zener diode How might two similar SCRs be connected to safely distribute the power load of a circuit? In parallel, reverse polarity What are the three terminals of a TRIAC? Gate, anode 1, and anode 2. What circuit might contain a SCR? A light-dimming circuit. What is one common use for PIN diodes? RF switch. What type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies? Varactor diode What is the principal characteristic of a tunnel diode? Negative resistance region What are the three terminals of a bipolar transistor? Base, collector and emitter What is the meaning of the term "beta" with regard to bipolar transistors? The change of: Collector current with respect to base current What are the elements of a unijunction transistor? A. Base 1, base 2, and emitter. The beta cutoff frequency of a bipolar transistor is the frequency at which: Emitter current gain has decreased .707 of maximum. What does it mean for a transistor to be cut-off? There is no current between emitter and collector. An emitter-follower More current gain than common emitter or common base. For current to flow in an NPN silicon transistor's emitter-collector junction, the base must be: At least .7 v positive with respect to the emitter What type of bias is required for an LED to produce luminescence? Forward bias What determines the visible color radiated by an LED? The materials used to construct the device What circuit component must be used in series to protect an LED? Series resistor What describes a diode junction that is forward biased? It is a low impedance What is the piezoelectric effect? Mechanical vibration of a crystal by the application of a voltage. An electrical relay is a: Remotely controlled switching device. How could voltage be greater across reactances in series than the applied voltage? Resonance What is the characteristic of the current flow in a series R-L-C circuit at resonance? Maximum What is the relationship between current through a resonant circuit and the voltage across the circuit? The voltage and current are in phase What is the main advantage of using an op-amp audio filter over a passive LC audio filter? Op-amps exhibit gain rather that insertion loss Which of the following op-amp circuits is operated open-loop? Comparator In the op-amp oscillator circuit shown in Figure 3D6, what would be the most noticeable effect if the capacitance of C were suddenly doubled? Frequency would be lower What frequency synthesizer circuit uses a phase comparator, look-up table, digital-to-analog converter, and a low-pass antialias filter? A direct digital synthesizer A circuit that compares the output of a voltage-controlled oscillator(VCO) to a frequency standard and produces and error that is then used to adjust the capacitance of a varactor diode used to control the frequency in that same VCO is called what? Phase-locked loop What is the definition of a phase-locked loop (PPL) circuit? A servo loop consisting of a phase detector, a low-pass filter and voltage-controlled oscillator VCO Which lamps would be lit in the circuit shown in Figure 3D8? A. 2, 3, 4, 5 and 6. B. 5, 6, 8 and 9. C. 2, 3, 4, 7 and 8. D. 1, 3, 5, 7 and 8. C What will occur if an amplifier input signal coupling capacitor fails open? No amplification will occur, with DC within the circuit measuring normal. With a pure AC signal input to the circuit shown in Figure 3D11, what output wave form would you expect to see on an oscilloscope display? 2 or option B TTL inputs left open develop what logic state? A high-logic state. Which of the following instruments would be best for checking TTL logic circuits? Logic probe What do the initials TTL stand for? transistor-transistor logic What is the characteristic of an "AND" gate? Produces a logic "1" at its output only if all inputs are logic "1" What is a characteristic of a "NOR" gate? Produces a logic "0" at its output if any or all inputs are logic "1". Which of the following logic gates will provide an active high out when both inputs are active high? AND gate For the logic input levels shown in Figure 3E12, what are the logic levels of test points A, B and C in this circuit? (Assume positive logic.) A is low, B is high and C is high Give the input levels shown in figure 3E14 and assuming positive logic devices, what would the output be? A is low, B is high and C is high A flip-flop circuit is a binary logic element with how many stable states? 2 How many flips-flops are required to divide a signal frequency by 4? 2 An R-S flip-flop is capable of doing all of the following except: Operate a toggle mode with R-S inputs held constant and CLK initiated. What is an astable multivibrator? A circuit that alternates between two unstable states. What is a bistable multivibrator circuit commonly named? Flip-flop What wave form would appear on the voltage outputs at the collectors of an astable, multivibrator, common-emitter stage? Square wave What is the name of a semiconductor memory IC whose digital data can be written or read, and whose memory word address can be accessed randomly? RAM- Random-Access Memory What does the term "I/O" mean within a microprocessor system? Input-Output In a microprocessor-controlled two-way radio, a "watchdog" timer: Verifies that the microprocessor is executing the program What circuit interconnects the microprocessor with the memory and input/output system? Data bus line What integrated circuit device converts an analog to digital signal? ADC What integrated circuit device converts digital signals to analog? DAC In binary numbers 0010 What is the limiting condition for sensitivity in a communication receiver? The noise floor of the receiver What is the definition of the term "receiver desensitizing?" A reduction in receiver sensitivity because of a strong signal on a nearby frequency What is the term used to refer to a reduction in receiver sensitivity caused by unwanted high-level adjacent channel signals? Desensitizing How much gain should be used in the RF amplifier stage of a receiver? Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage Too much gain in a VHF receiver front end could result in this: Susceptibility of intermodulation interference from nearby transmitters What is the advantage of GaAsFET preamplifier in a modern VHF receiver? High gain and low noise floor Why is the Colpitts oscillator circuit commonly used in a VFO (variable frequency oscillator)? A. It can be phase locked. B. It can be remotely tuned. C. It is stable. D. It has little or no effect on the crystal's stability. It is stable What is the oscillator stage called in a frequency synthesizer? Voltage controlled oscillator (VCO) What condition must exist for a circuit to oscillate? Have sufficient positive feedback What is the mixing process in a radio receiver? The combination of two signals to produce sum and difference frequencies. What are the principal frequencies that appear at the output of a mixer circuit? The original frequencies and the sum and difference frequencies If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal to produce a 455 kHz intermediate frequency (IF) signal, what type of interference will a 13.345 MHz signal produce in the receiver? An image response What degree of selectivity is desirable in the IF circuitry of a wideband FM phone receiver? 15kHz Which of these filters can be used in micro-miniature electronic signals? Receiver SAW IF filter How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal? Slightly greater than the receiver-signal bandwidth What is the primary purpose of the final IF amplifier stage in a receiver? Gain What factors should be considered when selecting an intermediate frequency? Image rejection and selectivity What parameter must be selected when designing an audio filter using an op-amp? Bandpass characteristics What are the three general grouping of filters? High pass, low-pass and band-pass What is an advantage of a constant k-filter? A. It has high attenuation of signals at frequencies far removed from the pass band. What are the distinguishing features of a Butterworth filter? It has a maximally flat response over its passband What is the product detector? It uses a mixing process with a locally generated carrier. Which circuit is used to detect FM-phone signals? frequency discriminator What is a frequency discriminator in a radio receiver? A circuit for detecting an FM signals What is the purpose of de-emphasis in the receiver audio stage? When coupled with a transmitter pre-emphasis, flat audio and noise reduction is received. What causes a squelch circuit to function? Presence of noise What radio circuit samples analog signals, records and processes them as numbers, then converts them back to analog signals? The digital signal processing unit How can ferrite beads be used to suppress ignition noise? Install them: Install them in the primary and secondary ignition leads What is the term used to refer to the condition where the signals from very strong station are superimposed on other signals being received? Cross-modulation interference In Figure 3F15 at what point in the circuit (labeled 1 through 4) could a DC voltmeter be used to monitor signal strength? 4 What is the distinguishing feature of a Class A amplifier? Output for the entire 360 degrees of the signal cycle Which class of amplifiers has the highers linearity and least distortion? Class A Which class of amplifiers provides the highest efficiency? Class C What input-amplitude parameter is most valuable in evaluating the signal-handling capability of a Class A amplifier? Peak voltage The class C amplifier output is present for what portion of the input cycle? Less than 180 degrees What class of amplifiers is characterized by conduction for 180 degrees of the input wave? Class B How does the modulation index of a phase-modulated emission vary with RF carrier frequency? It does not depend on the RF carrier frequency How can single-sideband phone signal be generated? By using a balanced modulator followed by a filter. What is a balanced modulator? A modulator that produces a double sideband, suppressed carrier signal. What is a pi-network? A. A network consisting of a capacitor, resistor and inductor. B. The Phase inversion stage. C. An enhanced token ring network. D. A network consisting of one inductor and two capacitors or two inductors and one capacitor. A network consisting of one inductor and two capacitors or two inductors and one capacitor. What is a pi-L network? A. A Phase Inverter Load network. B. A network consisting of two inductors and two capacitors. C. A network with only three discrete parts. D. A matching network in which all components are isolated from ground. A network consisting of 2 inductors and 2 capacitors Which network provides the greatest harmonic suppression? Pi-L network What will occur when a non-linear amplifier is used with a single-sideband phone transmitter? Distortion In a single-sideband phone signal, what determines the PEP-to-average power ratio? The speech characteristics What is the approximate ratio of peak envelope power to average power during normal voice modulation peak in a single-sideband phone signal? 2.5 to 1 How can parasitic oscillations be eliminated in a power amplifier? By neutralization What is the name of the condition that occurs when the signals of 2 transmitters in close proximity mix together in one or both of their final amplifiers, and unwanted signals at the sum and difference frequencies of the original transmissions are generated? Intermodulation interference What is the modulation type that can be a frequency hopping of one carrier or multiple simultaneous carriers? Spread spectrum The deviation ratio is the? Maximum carrier frequency deviation to the highest audio modulating frequency. What is the deviation ratio for the FM phone signal having a maximum frequency deviation of plus or minus 5 kHz and accepting a maximum modulation rate of 3 kHz? 1.66 What is it meant by the term "modulation index"? The ratio between the deviation of a frequency modulated signal and the modulating frequency In Figure 3H17, the block labeled 4 would indicate that this schematic is most likely a/an: SSB radio transmitter In figure 3H17, which block diagram symbol (labelled 1 though 4) presents where audio intelligence is inserted? 2 What does a two-tone test illustrate on an oscilloscope? Linearity and SSB transmitter What is an important factor in pulse-code modulation using time-division multiplex? Synchronization of transmit and receive clock pulse rates What is the name of the type of modulation in which the modulating signal varies the duration of the transmitted pulse? Pulse-with modulation In a pulse-position modulation system, what parameter does the modulating signal vary? The time at which each pulse occurs When a lead-acid storage battery is being charged, a harmful effect to humans is: Emission of hydrogen gas The average fully-charged voltage of a lead-acid storage cell is: 2.06 v A nickel cadmium cell has an operating voltage of about? 1.25 v When an emergency transmitter uses 325 watts and a receiver uses 50 watts, how many hours can a 12.6 volt, 55 ampere-hour battery supply full power to both units? 1.8 hours What current will flow in a 6 volt storage battery with an internal resistance of .01 ohms, when a 3-watt, 6volt lamp is connected? .4995 amps A ship RADAR unit uses 315 watts and a radio uses 50 watts. If the equipment is connected to a 50 ampere-hour battery rated at 12.6 volts, how long will the battery last? 1 hour 43 minutes What occurs if the load is removed from an operating series DC motor? It will accelerate until it falls apart If a shunt motor running with a load has its shunt field opened, how would this affect the speed of the motor? A. It will slow down. B. It will stop suddenly. C. It will speed up. D. It will be unaffected. It will speed up The output of a separately-excited AC generator running at a constant speed can be controlled by: The amount of field current Which of the following could cause a high standing wave ratio on a transmission line? A detuned antenna coupler A radio frequency device that allows RF energy to pass though in one direction with very little loss but absorb RF power in the opposite direction is a? Isolator What is meant by the term "antenna bandwith"? The frequency range over which an antenna can be expected to perform well Which of the following represents the best standing wave ratio (SWR)? 1:1 At the end of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna? Maximum voltage and minimum current An antenna radiates a primary signal of 500 watts output. If there is a 2nd harmonic output of 0.5 watt, what attenuation of the 2nd harmonic has occurred? 30 dB A vertical 1/4 wave antenna receives signals: Equally from all horizontal directions. The resonant frequency of a Hertz antenna can be lowered by? Placing an inductance in series with the antenna To lengthen an antenna electrically, add a ? Coil What is the meaning of the term velocity factor of a transmission line? The velocity of a wave on the transmission line divided by the velocity of light in a vacuum What determines the velocity factor in a transmission line? Dielectrics of the line A perfect (no loss) coaxial cable has 7 dB of reflected power when the input is 5 watts. What is the output of the transmission line? 1 watt What is the effective radiated power of a repeater with 75 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and a circulator loss, and 6 dB antenna gain? 37.6 watts What is the effective radiated power of a repeater with 100 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and a circulator loss, and 7 dB antenna gain? 100 watts What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and a circulator loss, and 7 dB antenna gain? 31.5 watts What is the frequency range of the Distance Measuring Equipment (DME) used to indicate an aircraft's slant range distance to a selected ground-besed station? 962 MHz to 1213 MHz What radio navigation aid determines the distance from an aircraft to a selected VORTAC station by measuring the length of time the radio signal takes to travel to and from the station? Distance measuring equipment (DME) The majority of airborne Distance Measuring Equipment systems automatically tune their transmitter and receiver frequencies to the paired __ / __ channel. VOR/LOC All directions associated with a VOR station are related to: Magnetic north Lines drawn from the VOR station in a particular magnetic direction are: Radials The amplitude modulated variable phase signal and the frequency modulated reference phase signal of a very-high-frequency Omnidirectional Range(VOR) station used for aircraft navigation are synchronized so that both signals are in phase with each other at _____of the VOR station 360 degrees north, magnetic bearing position What is the frequency range of the localizer beam system used by aircraft to find the centerline of a runway during an Instrument Landing System (ILS) approach to an airport? 108.10 MHz to 111.95 MHz Which of the following is a required component of an Instrument Landing System (ILS)? Localizer: Shows aircraft deviation horizontally from center of runway What type of antenna is used in an aircraft's Instrument Landing System (ILS) glideslope installation? A folded dipole reception antenna What is the frequency range of an aircraft's Automatic Direction Finding (ADF) equipment? 190 kHz to 1750 kHz What are the transmit and receive frequencies of an aircraft's mode C transponder operating in the Air Traffic Control RADAR Beacon System (ATCRBS)? Transmit at 1090 MHz, and receive at 1030 MHz What type of encoding is used in an aircraft's mode C transponder transmission to a ground station of the Air Traffic Control RADAR Beacon System (ATCRBS)? A. Differential phase shift keying. B. Pulse position modulation. C. Doppler effect compressional encryption. D. Amplitude modulation at 95%. Pulse position modulation Aircraft Emergency Locator Transmitter (ELT) operate on what frequencies? 121.5 and 406 MHz What is the frequency range of an aircraft's radio altimeter? 4250 MHz to 4350 MHz Aviation services use predominantly ___microphones Dynamic Typical airborne HF transmitters usually provide a nominal RF power output to the antenna of ____ watts, compared with ____ watts RF output from a typical VHF transmitter. 100, 20 What type of antenna is used in an aircraft's VOR and Localizer installation? Horizontally polarized omnidirectional antenna A 50 mico-ampere meter movement has an internal resistance of 2,000 ohms. What applied voltage is required to indicate half-scale deflection? .05 volts What is the purpose of a series mulitplier resistor used with a voltmeter? It is used to increase the voltage-indicating range of the voltmeter What instrument is used to indicate high and low digital voltage states? Logic probe How is a frequency counter used? To measure the time between events, or the frequency, which is the reciprocal of the time. What equipment may be useful to track down EMI aboard a ship of aircraft? Portable AM receiver On an analog wattmeter, what part of the scale is most accurate and how much does the accuracy extend to the rest of reading scale? The accuracy is only at full scale, and that absolute number is carried though the rest of the range. The upper 1/3 of the meter is the only truly calibrated part An oscilloscope can be used to accomplish all of the following except:? Measure velocity of light with the aid of a light emitting diode What does the horizontal axis of a spectrum analyzer display? Frequency What does the vertical axis of a spectrum analyzer display? Amplitude What test instrument can be used to display spurious signals in the output of a radio transmitter? A spectrum analyzer What is the common method used to program radios with out using a "wired" connection? Infra-red communication What is the common method for determining the exact sensitivity specification of a receiver? Measure the recorded audio for 12 dB of SINAD A communications technician would perform a modulation-acceptance bandwith test in order to ? Determine the effective bandwith of a communication receiver When soldering or working with CMOS electronics products or equipment, a wrist strap must have? Must have less that 100,000 ohms of resistance to prevent static electricity Which of the following is the preferred method of cleaning solder from plated-through circuit-board holes? Use a vacuum device What is the proper way to cut plastic wire ties? With flush-cut diagonal pliers and cut flush. Why should you not use white or translucent plastic tie wraps on a radio tower? UV radiation from the sun deteriorates the plastic very quickly What type of wire would connect an SSB automatic tuner to an insulated backstay? A. GTO-15 high-voltage cable. B. RG8U. C. RG213. D. 16-gauge two-conductor. GTO-15 high-voltage cable On a 150 watt marine SSB HF transceiver, what would be indicated by a steady output of 75 watts when keying the transmitter on? There is probably defect in the system causing the carrier to be transmitted The tachometer of a building's elevator circuit experience interference cause by the radio system nearby. What is the common potential "fix" for the problem? Add a .01 uF capacitor across the motor/tachometer leads Name 2 types of spread spectrum systems used in most RF communication applications? Direct sequence and frequency hopping A TDMA radio uses what to carry multiple conversations sequentially? Separate time slots Which of the following statements about the SSB voice transmissions is correct? They normally use 3JE emissions, which consists of one sideband and a suppressed carrier The GSM Global System for Mobile communications uses what type of CODEC for digital mobile radio system communications? Regular-Pulse Excited (RPE) The international organization for standardization had developed a 7 level reference model for a packet-radio communications structure. What level is responsible for the actual transmission of data The physical layer International Organization for Standardization has developed a 7 level model for a packet-radio communication structure. The _____level arranges the bits into frames and controls data flow. Link layer Which statement best describes the code used for GMDSS-DSC transmission? A 10 bit error correcting code starting with bits of data followed by a 3 bit error correcting code Which is the code used for SITOR-A and -B transmissions? A. The 5 bit baudot telex code. B. Each character consists of 7 bits with 3 "zeros" and 4 "ones". C. Each character consists of 7 bits with 4 "zeros" and 3 "ones". D. Each character has 7 bits of data and 3 bits for error correction. Each character consists of 7 bits with 4 "zeros" and 3 "ones" Which of the following statements is true? A. The signal repetition character (1001100) is used as a control signal in SITOR-ARQ B. The idle signal (a) (0000111) is used for FEC Phasing Signal 1 C. The idle signal (b) (0011001) is used for FEC Phasing Signal 2 D. The Control Signal 1 (0101100) is used to determine the time displacement in SITOR-B The idle signal (a) (0000111) is used for FEC Phasing Signal 1 What is the channel spacing used for the USA-INT control or function? It changes some channels that are normally duplex channels into simplex channels How might an installer verify correct GPS sentence to marine DSC VHF radio? Look for latitude and longitude, plus speed, on VHF display What is a common occurrence when voice-testing SSB aboard a boat? Voltage panel indicator lamps may glow with each syllable Which of the following statements SITOR communications is true? A. ARQ message transmissions are made in data groups consisting of three-character blocks. B. ARQ transmissions are acknowledged by the Information Receiving Station only at the end of the message. C. ARQ rely upon error correction by time diversity transmission and reception. D. Forward error correction is an interactive mode. ARQ message transmissions are made in data groups consisting of three-character blocks The sequence ARQ, FEC, SFEC best corresponds to which of the following sequences? A. One-way communication to a single station, one-way communications to all stations, two-way communications. B. Two-way communications to all stations, two-way communications, one-way communication to a single station. C. Two-way communications, one-way communications to all stations, one-way communications to a single station. D. Two-way communications, one-way communications to a single station, one-way communications to all stations. Two-way communications, one-way communications to all stations, one-way communications to a single station What causes a SART to begin a transmission? After being activated the SART responds to RADAR interrogation. How should the signal from a Search And Rescue Radar Transponder appear on a RADAR display? A series of 12 equally spaced dots What statement is true regarding 406 MHz EPRIB transmission? Transmits a unique hexadecimal identification number What is a facsimile? The transmission of printed pictures for permanent display on paper. What is the standard scan rate for high-frequency 3 MHz - 23 MHz weather facsimile reception from shore station? 120 lines/sec What would be the bandwith for a good crystal lattice band-pass filter for weather facsimile HF (high frequency) reception? 1 kHz at -6 dB How should shielding be grounded on an NMEA 0183 data line? A. Unterminated at both ends. B. Terminated to ground at the talker and unterminated at the listener. C. Unterminated at the talker and terminated at the listener. D. Terminated at both the talker and listener. Terminated to the ground at the talker and unterminated at the listener What might occur in NMEA 2000 network topology if one device in line should fail? There will be no interruption to all other devices What voltage drop at the end of the last segment will satisfy NMEA 2000 network cabling plans? 1.5 volts What is the normal range of pulse repetition rates? 500 to 2,000 pps What is the normal range of pulse width? .05 µs to .1 µs Shipboard RADAR is most commonly operated in what band? A. VHF. B. UHF. C. SHF. D. EHF. SHF What is the purpose or function of RADAR duplexer/circulator? It is a/an: Electronic switch that allows the use of one antenna for both transmission and reception What device can be used to determine the performance of RADAR system at sea? Echo box Digital signal processing (DSP) of RADAR signals (compared with analog) causes? Improved weak signal or target enhancement We are looking at a target 25 miles away. When a RADAR is being operated on the 25 mile range setting what is the most appropriate pulse width and pulse repetition rate? 1.0 µs PW and 500 pps What pulse width and repetition rate should you use at long ranges? Wide pulse width and slow repetition rate What pulse width and repetition rate should you use at short ranges? Narrow pulse and fast repetition rate What happens to the beamwidth of an antenna as the gain increases? The beam width: Decrease as the gain increases Conductance takes place in a waveguide: A. By interelectron delay. B. Through electrostatic field reluctance. C. In the same manner as a transmission line. D. Through electromagnetic and electrostatic fields in the walls of the waveguide. Through electromagnetic and electrostatic fields in the walls of the waveguide. To couple energy into and out of a waveguide use: A. Wide copper sheeting. B. A thin piece of wire as an antenna. C. An LC circuit. D. Capacitive coupling. A thin piece of wire an an antenna The permanent magnetic field that surrounds a Traveling-Wave Tube (TWT) is intended to: Prevent the electron beam from spreading Prior to testing and RADAR system, the operator should first: Assure no personnel are in front of the antenna RADAR collision avoidance systems utilize inputs from each of the following except your ship's: Anemometer What service are provided by the Iridium system? Digital voice and Data at 2.4 kbps Which of the following statements about the Iridium system is true? A. There are 48 spot beams per satellite with a footprint of 30 mile in diameter. B. There are 48 satellites in orbit in 4 orbital planes. C. The inclination of the orbital plane is 55 degrees. D. The orbital period is approximately 85 minutes. There are 48 spot beams per satellite with a footprint of 30 mile in diameter How does the COSPAS-SARSAT satellite system determine the position of a ship in distress? By measuring the Doppler shift of the 406 MHz signal taken at several different points in its orbit What is the orbital altitude of INMARSAT Satellites? 22,177 miles Which of the following describes the INMARSAT satellite system? AOR-E at 15.5° W, AOR-W at 54° W POR at 178° E and IOR at 64.5° E Which of the following conditions can render INMARSAT-B communication impossible? All of these What is the best description for INMARSAT-C system? It is a store-and-forward system that provides routine and distress communication The INMARSAT mini-M system is a: Satellite system utilizing spot beams to provide for small craft communications. When Inmarsat-B and Inmarsat-C terminals are compared: INMARSAT-C antennas are small and omni-directional, while INMARSAT-B antennas are larger and directional The GPS transmitted frequencies are ? 1227.6 MHz and 1575.4 MHz. What best describes the GPS Stallites orbits? They are in six orbital planes equally spaced and inclined about 55° to the equator What is DGPS? A system to provide additional correction factors to improve position accuracy. At what aggregate power level is an MPE (Maximum Permissible Exposure) study required? A. 1000 Watts ERP. B. 500 Watts ERP. C. 100 Watts ERP. D. Not required. 1000 Watts ERP Why must you never look directly into a fiber optic cable? A. High power light waves can burn the skin surrounding the eye. B. An active fiber signal may burn the retina and infra-red light cannot be seen. C. The end is easy to break. D. The signal is red and you can see it. An active fiber signal may burn the retina and infra-red light cannot be seen. If the MPE (Maximum Permissible Exposure) power is present, how often must the personnel accessing the affected area be trained and certified? Yearly What is the purpose of not putting sharp corner on the ground leads within a building? Lighting will jump off the ground lead because it is not able to make a sharp bend Do shorted-stub lightning protectors work at all frequencies? No, only at the tuned frequency band What is a GFI electrical socket used for? To prevent electrical shock by sensing ground path current and shutting the circuit down.