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 : ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K
Last Answer : C. 174 K
Description : What are the two basic types of preamplifiers used in fiber optic receivers?
Last Answer : The high-impedance amplifier and the transimpedance amplifier.
Description : What is the most probable cause of trouble in a synchro system that has all of its receivers reading incorrectly?
Last Answer : The transmitter or main bus.
Description : What IF frequencies are normally used in radar receivers
Last Answer : Thirty or sixty megahertz.
Description : What is the greatest limiting factor in a receiver’s detectable range
Last Answer : Noise.
Description : Why do earth terminals require highly sensitive receivers?
Last Answer : To overcome satellite transmitter low power and permit extraction of the desired information from the received signal.
Description : What is the main disadvantage of using fiber-optic cables?
Last Answer : High attenuation.
Description : Message can be sent more securely using DES by a. encrypting plain text by a different randomly selected key for each transmission b. encrypting plain text by a different random key for each ... instead of using hardware d. designing DES with high security and not publicizing algorithm used by it
Last Answer : b. encrypting plain text by a different random key for each message transmission and sending the key to the receiver using a public key system
Description : Which of these is a disadvantage of buying a house instead of renting?
Last Answer : Homeowners must pay for repairs themselves
Description : What is the main disadvantage of parallel transfer?
Last Answer : Requires more circuitry.
Description : What is the main disadvantage of a conventional full-wave rectifier?
Last Answer : Peak voltage is half that of the half-wave rectifier.
Description : Name a disadvantage of sine-wave oscillator synchronizers.
Last Answer : It requires additional shaping circuits.
Last Answer : . It requires additional shaping circuits.
Description : What is the main disadvantage of the conventional full wave rectifier?
Last Answer : The peak voltage is half that of a half-wave rectifier.
Description : What is the major disadvantage of printed circuit boards?
Last Answer : Components soldered in place.
Description : What is the major disadvantage of an fm signal as compared to an AM signal?
Last Answer : Wide bandpass.
Description : What is a disadvantage of agc?
Last Answer : Weak signals produce bias, which could result in no usable receiver output.
Description : What is the main disadvantage of PROM?
Last Answer : If a mistake is made and entered, it cannot be corrected or erased.
Description : How is the disadvantage of the Gramme-ring armature overcome in the drum-wound armature?
Last Answer : By winding the armature in a way that places the entire coil where it is exposed to maximum flux.
Description : What is the main disadvantage of a series motor?
Last Answer : It must have a load connected to avoid damage from excess speed.
Description : What is the main disadvantage of series generators?
Last Answer : Output voltage varies as the load varies
Description : What is a disadvantage of a direct-current system with respect to supply voltage?
Last Answer : the dc voltage must be generated at the level required by the load.
Description : What is the primary disadvantage of the pointer arrangement for indicating coil rotation?
Last Answer : Coil balance.
Description : What is the main disadvantage of the rhombic antenna?
Last Answer : It requires a large antenna site.
Description : What is the main disadvantage of pulse-position modulation?
Last Answer : It requires synchronization between the transmitter and receiver.
Description : What is a major disadvantage of a carbon microphone?
Last Answer : Background hiss resulting from random changes in the resistance between individual carbon granules.
Last Answer : Antenna-to-ground capacitance can cause the oscillator frequency to vary.
Description : Draw a neat sketch of moving primary fixed secondary double sided LIM. Write one advantage and one disadvantage of it.
Last Answer : Ans: Moving primary fixed secondary, double side LIM Advantages: i) No Need of backing of iron along the track as laminated core is used in each primary. ii) Uniform air gap ... of accidents result from change in gap due to sudden production of lateral forces on the moving vehicle.
Description : Hashed message is signed by a sender using a. his public key b. his private key c. receiver’s public key d. receiver’s private key
Last Answer : b. his private key
Description : What is the main reason for using a multispeed synchro system instead of a single-speed synchro system?
Last Answer : Greater accuracy without the loss of self-synchronous operation.
Description : What is the purpose of using differential synchros instead of regular synchros?
Last Answer : Differential synchros can handle more signals than regular synchros and also perform addition and subtraction functions.
Description : What two receiver leads are reversed to reverse the rotor's direction of rotation?
Last Answer : 1 and S3.
Description : Receiver bandwidth is defined as those frequencies spread between what two points of the receiver response curve?
Last Answer : Half-power points.
Description : What two components give a ssb receiver its advantages over an AM superheterodyne receiver?
Last Answer : A special type of detector and a carrier reinsertion oscillator
Description : When is a synchro receiver (TR) properly zeroed?
Last Answer : A TR is zeroed when electrical zero voltages exist across its stator windings at the same time its rotor is on zero or on its mechanical reference position.
Description : What is the most likely problem if the transmitter shaft reads 0º when the receiver shaft indicates 180º?
Last Answer : The rotor leads on either the transmitter or the receiver are reversed.
Description : What is the relationship between the transmitter and receiver stator voltages when their rotors are in correspondence?
Last Answer : The voltages are equal and oppose each other.
Description : What is the physical difference between a synchro transmitter and a synchro receiver?
Last Answer : A synchro receiver uses some form of damping to retard excessive oscillations or spinning.
Description : When measuring receiver sensitivity, what quantities must you add to the dBm reading obtained on the signal generator or test set?
Last Answer : Attenuations of the directional coupler and the connecting cable.
Description : You determine receiver sensitivity by measuring the power level of what signal?
Last Answer : Minimum discernible signal (mds).
Description : A loss of receiver sensitivity has the same effect on range performance as what other loss?
Last Answer : Transmitter power loss.
Description : Where should the transmitter spectrum be located with respect to the receiver response curve?
Last Answer : In the center.
Description : A monopulse receiver has how many separate channels?
Last Answer : Three.
Description : How does ftc affect receiver gain, if at all?
Last Answer : FTC has no effect on receiver gain
Description : Immediately after the transmitter fires, stc reduces the receiver gain to what level?
Last Answer : Zero.
Description : Which receiver component converts the IF pulses to video pulses?
Last Answer : Detector.
Description : What receiver circuit actually produces the IF frequency?
Last Answer : Mixer.
Description : Which component of the receiver produces the signal that is mixed with the received signal to produce the IF signal?
Last Answer : Local oscillator.