Module 26 e-review

wopapuxa's version from 2017-10-16 10:18


Question Answer
Tropospheric scatter is used with frequencies in the ff rangeUHF
When microwave signals follow the curvature of the Earth, this is known asDucting
A rhombic antenna is aNon-resonant antenna
Which of the following antennas is best excited by a waveguide? Horn
Which of the following does not apply to yagi-uda antenna? High gain
The standard reference antenna for directive gain is the Isotropic Antenna
Top loading is used with antenna in order to increase its Effective height
Cassegrain feed is used with a parabolic reflector to Allow the feed to be placed at a convenient point
A helical antenna is used for satellite tracking because of its Circular polarization
The effective height of sky wave propagation is More than its actual height
A diplex is used to Transmit two signals simultaneously at the same direction
To transmit signal simultaneously at the same direction one should use A Diplex
Data transmission rate in a telegraph is measured in Baud per sec
A scheme in which several channels are interleaved and then transmitted together is known as Frequency-division Multiplex
The number of repeaters along a coaxial cable link depends on The bandwidth of the system
A supergroup pilot is Fed in at GTE
Identical telephone numbers in different parts of a country are distinguished by their Area codes
Telephone traffic is measured in Erlangs
In order to separate channels in a TDM receiver, it is necessary to use AND gates
To separate channels in an FDM receiver, it is necessary to use Bandpass Filters
Increasing the length of an antenna has what effect on its directive gain Increase
The most common modulation system used for telegraphy is FSK
Interlacing is used in television to Avoid flicker
Typical Aspect ratio of television 4:3
Equalizing pulses in TV are sent during Vertical blanking
The function of serrations in the composite video waveform is to Help horizontal synchronization
The shadow mask in a picture color tube is used to Ensure that each beam hits only its own dots
FM broadcasting occurs in which ranges VHF and UHF
A balanced modulator is used to eliminate the Carrier
How many balanced modulator and phase shift circuits are need to produce a SSB signal? 2,2
The impedance of a half wave antenna is 73 ohms
The gain of a half wave antenna is 2.15 dB
The most common antenna used in AM ( medium wave band) broadcasting Grounded Vertical antenna
AM ( medium wave band) frequency range500-1600
Bandwidth of an FM broadcasting system200 z
Range of frequencies in which sky-wave propagation is most efficient8-35 Hz
In CCIR-B system, what is the typical bandwidth used? 5 MHz
What is the separation between the audio and visual carrier in the CCIR-B system 5.5 MHz
Line rate in CCIR-B system 15625 lines/sec
In CCIR-B system how many lines are there in a frame 625 lines
In CCIR B system for television, horizontal sync back porch is 0.03H
In CCIR B system for television, front porch is 0.025H
In CCIR B system for television, complete 2.5H
In CCIR B system for television, post equalizer is 2.5H
If the sound carrier in CCIR-B system is 87.75 MHz. What is the frequency of the picture carrier? 82.25 MHz
In CCIR B system for television, pre-equalizer is2.5H
Skip distance is Independent of the transmit power
Interference from adjacent telegraph channels Cross fire
Armstrong modulation produces Phase modulation
In CCIR system, active frames 585
Audible threshold range of hearing -10 dB
Good quality of record player 15 Hz to 50 kHz
Baseband of telephone .3 kHz to 3.4 kHz
Telex is Teleprinter and services exchange
Adjacent phone line interference Cross talk
Buffer isolates Master oscillator and the load
Frequency multiplier should operate in what class of amplifier? Class C
Microphone that does not exhibit flat curve Carbon Microphone
……. Noise background (PLEASE ADD) Carbon Microphone
Microphone that does not need a polarized current Ribbon Microphone
Type of microphone in telephone …. (PLEASE ADD) Fixed Coil
Type of microphone used in telephone handset Carbon microphone
Microwave antenna has Low input impedance
Type of modulation used in picture and sound respectively AM and FM
Type of AM/video modulation in television Vestigial sideband
The ionosphere extends from 50 km and beyond the earth radii
Type of antenna that uses circular polarization Helical
The advantage of adlock antenna is that it is free from Night error
Disadvantage of adlock Small output voltage
Type of antenna used as a direction finder Loop antenna
If the aeroplane is above the conic of silence It is directly above the antenna
If the aeroplane approaches a beacon It increases and then suddenly disappears
Ship-to-ship shore, to experience reliable link Frequency Diversity
Satellite communications range 3000 to 30000 MHz
Atmospheric noise is most prominent at frequencies Below 30 MHz
UHF uses Space wave propagation
Will not align (PLEASE ADD) Audio Amplifier
Vidicon is Photoconductive
To make the transmission line an antenna Fold its ends by 90 degrees
Medium wavesHorizontal waves are greatly attenuated
Endfire array and broadside antenna provides Higher bandwidth
At very high frequencies earth acts like a Dielectric
How do you physically connect transmitters that are physically connected Link coupling
How to make linear ….. (PLEASE ADD) Arrays that are equally spaced at a single line
In CCIR B system, ratio radiated of vision power to sound power is 1:1
Gain or level of video signal in the television receiver is provided by Contrast Control
Night effect is most prominent in Loop antenna