Description : ECE Board Exam March 1996 What is the purpose of the receiver's squelch circuit? A. To overcome fluctuations in the level the RF signal arriving at the receiver antenna B. To prevent ... signals D. To prevent amplified noise from reaching the loudspeaker during the absence of an incoming signal
Last Answer : D. To prevent amplified noise from reaching the loudspeaker during the absence of an incoming signal
Description : One of the FM signal generator control which varies the phase of the modulating voltage applied to the oscillator of the sweep generator A. Band control B. Phase control C. Marker amplitude control D. Sweep output control
Last Answer : B. Phase control
Last Answer : VCO - Viceroy Commissioned Officer
Description : A Voltage Controlled Oscillator (VCO) is an instrument : - a) whose frequency is dependent upon the amplitude of input signal b) whose frequency is independent upon the amplitude of input signal c) whose frequency is dependent upon the frequency of input signal d) none of the above
Last Answer : A Voltage Controlled Oscillator (VCO) is an instrument : - whose frequency is dependent upon the amplitude of input signal
Description : Indicate the false statement. Noise figure is defined as A. the ratio of the S/N power supplied at the input terminal of a receiver or amplifier to the S/N power supplied to the output or ... under test, both working at the same temperature over the same bandwidth and fed from the same source
Last Answer : C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals
Description : What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna ... D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna
Last Answer : D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna
Description : ECE Board Exam March 1996 What is the purpose of a beat frequency oscillator (BFO)? A. Aid in the reception of weak voice-modulated signals B. Generates a signal, whose frequency is the ... reception D. Generates an output, whose frequency differs from that of the intermediate frequency by 1 kHz
Last Answer : C. Generates a 1kHz note for Morse code reception
Description : What type of transmission is radiated from an aircraft’s radio altimeter antenna? A. An amplitude modulated continuous wave B. A pulse position modulated UHF signal C. A differential phase shift keyed UHF signal D. A frequency modulated continuous wave
Last Answer : D. A frequency modulated continuous wave
Description : The bending of radio waves passing over the top of a mountain range that disperses a weak portion of the signal behind the mountain is A. eddy-current phase effect B. knife-edge diffraction C. shadowing D. mirror refraction effect
Last Answer : B. knife-edge diffraction
Description : What is the phase delay of an 800 Hz voice signal if the phase shift is 15 degrees? A. 1.25 µsec B. 52 µsec C. 83.33 µsec D. 26 µsec
Last Answer : B. 52 µsec
Description : Define lock-in range of a PLL.
Last Answer : The range of frequencies over which the PLL can maintain lock with the incoming signal is called the lock-in range or tracking range. It is expressed as a percentage of theVCO free running frequency.
Description : A station in a network forwards incoming packets byplacing them on its shortest output queue. Whatrouting algorithm is being used? A. hot potatorouting B. flooding C. static routing D. delta routing E. None of the above
Last Answer : hot potatorouting
Description : An alternator switchboard has a synchroscope and synchronizing lamps. If the synchroscope is broken, which of the steps listed is the most essential before an alternator can be paralleled with the bus? ... D. A portable phase sequence indicator must be used to verify the information from the lamps.
Last Answer : Answer: C
Description : Which of the following problems will occur if the circuit breaker of the incoming alternator is closed and it is 180° out of phase with the loaded alternator when paralleling? A. The rotor of the ... The rotor of the incoming alternator will stop. D. Both alternators will parallel 180° out of phase.
Last Answer : Answer: B
Description : When paralleling two alternators, the synchronizing lamps remain lit as the synchroscope pointer approaches the 0°. This indicates the _____________. A. incoming alternator is running too fast B. alternator ... apart C. synchroscope is defective or broken D. alternator power factors are in phase
Description : When paralleling two alternators the synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position. This indicates the ____________. A. alternator voltages ... alternator is in phase with the bus voltage D. synchroscope pointer is defective or broken
Description : When paralleling two alternators using three synchronizing lamps, the flickering of all three lamps becomes progressively slower and slower. This means the ______________. A. frequency of the incoming ... the bus D. terminal voltage of the incoming alternator is approaching that of the bus
Last Answer : Answer: A
Description : You are attempting to parallel two AC generators, and the synchroscope pointer is revolving fast in the clockwise direction. This indicates that the frequency of the incoming machine is _____________. A. higher ... at any pointer position D. the same as the bus frequency but out of phase with it
Description : You are attempting to parallel two AC generators, and the synchroscope pointer is revolving in the fast direction. This indicates that the frequency of the incoming machine is _____________. A. higher ... the same as the bus frequency and the circuit breaker may be closed at any pointer position
Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0° prior to closing the circuit breaker. This indicates ___________. A. the frequency of ... be closed after breaker has been reset D. there is an existing cross current between generators
Description : You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine is _____________. A. higher than ... same as the bus frequency, and the circuit breaker may be closed at any pointer position
Description : Best description of a collinear and broadside antenna radiation pattern. A. Bidirectional B. Perfect circle C. Unidirectional D. Omnidirectional
Last Answer : A. Bidirectional
Description : Amplitude of modulated wave is in phase with A. output B. system C. frequency D. signal
Last Answer : signal
Description : If If the input signals are 180 degrees out of phase with each other and a combined output is taken between the two output terminals, what will the amplitude of the combined output signal be?
Last Answer : 200 millivolts.
Description : If the two input signals to a difference amplifier are equal in amplitude but neither in phase nor 180 degrees out of phase, what will the output signal be?
Last Answer : . A different shape than the input signals but larger in amplitude.
Description : If the two input signals to a difference amplifier are equal in amplitude and 180 degrees out of phase, what will the output signal be?
Last Answer : Equal in shape and frequency to each input signal and larger in amplitude by two times than
Description : . If the two input signals of a difference amplifier are in phase and equal in amplitude, what will the output signal be?
Last Answer : No output (the signals will "cancel out").
Description : The circuit which changes input signal at output with phase shift of 1800 is called (a) Amplifier (b) operational amplifier (c) switch (d) inverter
Last Answer : (d) inverter
Description : What is the difference in action of lock out pressure signal on 6.6 kV and 220 kV breakers?
Last Answer : When lock out signal comes to 6.6 kV breakers the breaker will trip. Where as in case of 220 kV breakers the breaker will not trip. If the breaker is open it will be open only and can not be closed. If it is in closed condition it will be closed.
Description : The DME in an aircraft, cruising at FL210, fails to achieve a lock on a DME at MSL at a range of 210nm. The reason for this is: a. The beacon is saturated b. The aircraft is beyond ... is beyond line of sight range d. The aircraft signal is too weak at the range to trigger a response
Last Answer : c. The aircraft is beyond line of sight range
Description : The loss in signal power as light travels down a fiber is called a. Dispersion b. Scattering c. Absorption d. Attenuation
Last Answer : d. Attenuation
Description : Stacking antenna elements A. increases sensitivity to weak signals B. will suppress odd harmonics C. decrease signal to noise ratio D. increases selectivity
Last Answer : A. increases sensitivity to weak signals
Description : Stacking antennas at various angles results in A. a more omnidirectional reception B. a more unidirectional reception C. a more omnidirectional reception D. an overall reception signal increase
Last Answer : A. a more omnidirectional reception
Description : What is the electrical wavelength of a 500 MHz signal? A. 60 centimeters B. 6 meters C. 0.06 meter D. 60 meters
Last Answer : A. 60 centimeters
Description : A simple half-wavelength antenna radiates the strongest signal A. at 45 degrees to its axis B. parallel to its axis C. at right angles to its axis D. at 60 degrees to its axis
Last Answer : C. at right angles to its axis
Description : Comparing the signal strength arriving at the driven element from the desired direction to the signal strength reaching the driver from the opposite direction. A. Directivity B. Sensitivity C. Beamwidth D. Front-to-back ratio
Last Answer : D. Front-to-back ratio
Description : A dipole antenna requires to be fed with 20 kW of power to produce a given signal strength to a particular distant point. If the addition of a reflector makes the same field strength available with an input power of 11kW ... Gain referred to this particular dipole). A. 4.75 B. 2.6 C. 1.81 D. 4.24
Last Answer : B. 2.6
Description : Very low signal strength in antenna. A. Minor lobes B. Null C. Antenna patterns D. Major lobes
Last Answer : B. Null
Description : What is the propagation delay when a signal is transmitter by an earth station to a geosynchronous satellite about 38,500 km above earth’s equator and then received by the same earth station? A. 256 msec B. 128 msec C. 300 msec D. 400 msec
Last Answer : A. 256 msec
Description : The signal path from satellite to earth-based receiver. A. Downlink signal B. Uplink signal C. Incident signal D. Reflected signal
Last Answer : A. Downlink signal
Description : Designed to receive a signal from a transmitting station on the ground and retransmit it to a receiving station located elsewhere A. Communication satellite B. Repeater C. Relay station D. Transponder
Last Answer : A. Communication satellite
Description : The signal path from earth station satellite A. Uplink signal B. Reflected signal C. Incident signal D. Downlink signal
Last Answer : A. Uplink signal
Description : A satellite which simply reflects the signal without further amplification A. Passive satellite B. Active satellite C. Geostationary satellite D. Domestic satellite
Last Answer : A. Passive satellite
Description : Is a loss of power of a satellite downlink signal due to earth’s atmosphere. A. Atmospheric loss B. Path loss C. Radiation loss D. RFI
Last Answer : B. Path loss
Description : _________ detects the satellite signal relayed from the feed and converts it to an electric current, amplifies and lower its frequency. A. Horn antenna B. LNA C. Satellite receiver D. Satellite dish
Last Answer : B. LNA
Description : A satellite signal transmitted from a satellite transponder to earth’s station. A. Uplink B. Downlink C. Terrestrial D. Earthbound
Last Answer : B. Downlink
Description : Noise occurring in the presence of signal resulting from a mismatch between the exact value of an analog signal and the closet available quantizing step in a digital coder. A. Quantizing noise B. Thermal noise C. Impulse noise D. Crosstalk
Last Answer : A. Quantizing noise
Description : The difference between signal strength at a given point and a reference level is________. A. power B. dBm C. level D. ratio
Last Answer : C. level
Description : Where is the noise generated that primarily determines the signal-to-noise ratio in a VHF (150MHz) marine-band receiver? A. Man-made noise B. In the atmosphere C. In the receiver front end D. In the ionosphere
Last Answer : C. In the receiver front end
Description : Deemphasis in the receiver in effect attenuates modulating signal components and noise in what frequency range? A. dc B. low C. intermediate D. high
Last Answer : D. high