This is the Section 3 Module 1 of the compiled Communications Coaching Materials taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize each questions to increase the chance of passing the ECE Board Exam.
Communications Engineering Coaching: Section 3 Module 1
· ISDN basic rate
Ans: 2B + 2D
· Access B data rate
Ans: 64 kbps
· Maximum diameter of fiber
Ans: rmax = 0.383λ/NA
· V number
Ans: V = πdNA/λo
· Neutralization is
Ans: Elimination of RF signals
· An IC of differential amplifier and on-chip
Ans: NE602
· Distance of microwave repeater of fiber optic
Ans: 6.215 – 18.65 mi
· IF up and down converter
Ans: 70 MHz
· Height of GLONASS
Ans: 19100 km
· Accuracy of GPS
Ans: 2 nautical miles
· Phase shift
Ans: β = √(ωδu/2)
· Negative transmission, medium gray
Ans: 40%
· Negative transmission, tip of sync
Ans: 100%
· Negative transmission, blanking level
Ans: 75%
· Negative transmission, black
Ans: 67.5%
· Negative transmission, maximum white
Ans: 12.5%
· Time for horizontal retrace
Ans: 10.2 us
· Path of telephone line crossing a private property and entering a building
Ans: Service entrance
· Cable within a building of series of buildings
Ans: Building cable
· Circular passage of cable
Ans: Pipe sleeve
· Marine radar communications
Ans: X-band
· Civil aircraft
Ans: 30-100 MHz
· Aircraft long range communications
Ans: 2 – 30 MHz
· Wireless telegraph
Ans: 1895
· Telegraph
Ans: 1844
· Telephone
Ans: 1876
· Radio
Ans: 1887
· Average splice of fiber optic
Ans: 0.15 dB
· Pilot subcarrier frequency
Ans: 19 kHz
· A subcarrier set by music
Ans: 67 kHz
· Travelling wave antenna
Ans: Rhombic antenna
· Brightness or illumination
Ans: contrast
· Amplitude of the signal
Ans: Contrast
· Out of control
Ans: Singing
· Frequency above 300 GHz
Ans: millimeter waves
· Micrwave operates
Ans: above 1 GHz
· Emits heat energy
Ans: Infrared
· A regulatory body whose sole purpose is allocating spectrum space, issuing licenses, setting standards and policing the airwaves.
Ans: FCC
· Government and military communications are coordinated by ___
Ans: NTIA
· The electromagnetic spectrum is managed by
Ans: ITU
· Characteristic impedance of coaxial cable
Ans: 75 Ω
· TDM used
Ans: PCM
· Telemetry data
Ans: PCM
· Frequency difference of color subcarrier and sound
Ans: 0.92 MHz
· Chroma signal
Ans: 3.58 MHz
· LORAN C frequency
Ans: 100 kHz
· Which cannot be used for range and bearing?
Ans: LORAN C
· Ceramic resonator at frequency of 200 – 500 kHz
Ans: Ceramic filter
· Multiple resonant disk
Ans: Mechanical bandpass filter
· Doubley balanced modulators and GaAs filters are best mixers for
Ans: VHF, UHF and microwave
· Layer of ionosphere for nighttime communications
Ans: F layer
· Which of the following is true?
Ans: Negative polarity has an amplitude decreases when white.
· Third letter
Ans: Type of information to be transmitted
· Lock range
Ans: PLL
· Critical part of FM receiver
Ans: Front end
· Advantage of superheterodyne receiver
Ans: excellent sensitivity and stability
· Disadvantage of TRF
Ans: Tuning and selectivity
· Ch.4 downlink frequency
Ans: 3.84 MHz
· λ/4 vertical λ/4 spaced and 90 degrees out of phase
Ans: Unidirectional Cardioid
· Discone antenna uses
Ans: Vertical polarization
· No gain antenna
Ans: Isotropic
· Token passing
Ans: IEEE 804.2
· PLL consists of
Ans: FM synthesizer and FM demodulator
· Simplest AM receiver
Ans: TRF
· MF range
Ans: 300 kHz- 3 MHz
· 1 pixel
Ans: 0.125 us
· Folded dipole is ____ the feedpoint of a dipole.
Ans: 4
· Resonant frequency tuned to the resonant circuit tuned to the multiple input of the signal
Ans: Frequency multiplier
· Time constant for pre-emphasis and de-emphasis network
Ans: 75 us
· To compress voice signal dynamic range
Ans: Companding
· Amplifier for PCM
Ans: Sample and Hold circuit
· Cut off
Ans: Class B
· 90 degrees to 150 degrees
Ans: Class C
· Benefits of multiplexing
Ans: Economy
· TV picture tube
Ans: kinescope
· Phase angle in TV
Ans: hue
· Linear amplifier
Ans: Class A
· Transmission range
Ans: TR = (2h)/(tan β)
· Frequency of reverberation chamber
Ans: f = 125 3√(180/V)
· Advantage of FM over AM
Ans: Noise immunity
· Disadvantage of FM
Ans: Wider bandwidth
· Floor area within a building that is usable and rentable
Ans: Rentable Floor Area
· Code for touch tone dialing
Ans: two-to-seven
· Increasing the amplitude level of higher frequency on modulating frequency
Ans: Pre-emphasis network
· Cable that is entering the building
Ans: Entrance Cable
· Comprises of telephone equipment; transmitter/receiver, etc.
Ans: Station.
· A telephone line that do not serve exchange
Ans: Private Line
· It is used to connect private branch exchange and central office
Ans: Trunk Line
· Most widely used fiber optic cable
Ans: Single mode step index.
· Most widely used RF transformer
Ans: Toroid
· Advantages of toroidal core
Ans: Fewer turns, Higher Q, and no shielding
· Refers to the general (whole) telephone company that serves communications
Ans: Plant
· It is used to increase the power level of AM and other sidebands
Ans: Class A or B
· It does not affect by the RF carrier
Ans: Phase modulated emission
· Time required for the horizontal scanning line
Ans: 63.6 us
· It must be on during horizontal flyback time
Ans: Burst separator
· Controls the phase angle of modulated color signal in TV
Ans: Tint
· Non-resonant antenna
Ans: V-antenna
· Information on altitude, etc. of an aircraft
Ans: Air data
· End line of communication
Ans: Station wiring
· Holds wires, they are conduits
Ans: Raceway
· It contains PBX
Ans: Equipment room
· Line of sight frequency
Ans: VHF and UHF
· An antenna used for VHF and higher frequency
Ans: Omnidirectional antenna
· Frequency conversion and translation
Ans: Heterodyning
· Cable connected to a cross connect terminal and not directly connected to the local exchange
Ans: Home cable
· Maximum propagation delay of GEO
Ans: 278 us
· Velocity factor of open-wire line
Ans: 0.9
· Velecoity factor of coaxial line
Ans: 0.8
· Most widely used modulator
Ans: Balanced modulator
· Multielement system for control
Ans: Key system
· Narrowband still picture
Ans: Slow scan TV
· Average power emitted by laser
Ans: pulse energy x repetition rate
· PCM system used in telephone network and uses TDM technique
Ans: Bell T1
· Sampling interval of T1 system
Ans: 25 us
· Widely used TV modulator
Ans: Quadrature detector
· Cut-off audio output to prevent annoying noise
Ans: Squelch
· Permits selective signaling
Ans: CTCS – continuous tone control squelch
· Cut-off frequency of pre-emphasis and de-emphasis network
Ans: 2122 Hz
· Feedback system used to correct the frequency drift of VHF, UHF and microwave frequency receivers
Ans: AFC (automatic frequency control)
· Produces excellent deviation FM for frequencies below 1 MHz
Ans: IC VCO
· Period of visible H
Ans: 12.5 us
· Period of equalizing pulse
Ans: 2.29 us
· Delay of geosynchronous satellite
Ans: 278 us
· A VCO in which frequency is varied in proportion to the amplitude of modulating DC or AC signal
Ans: Subcarrier oscillator
· All plants which are “out of doors” not inside the building
Ans: Outside plant
· All plants located inside the telephone public exchange building
Ans: Inside plant
· Used to terminate telephone wire cable
Ans: Distrubution frame
· It is used to terminate floor distribution cable
Ans: Floor Distribution Terminal
· Portion of a floor service by the floor distribution terminal
Ans: Floor terminal distribution area
· Branch cable of various floor used to connect floor distribution terminal to the riser cable
Ans: Floor distribution cable
· Upstream signal frequency of two wire cable
Ans: 5- 30 MHz
· It is found at the BPA of the TV
Ans: color level control
· 2 main barrier of communications
Ans: language and distance
· Raceway of rectangular cross section
Ans: header or feeder duct
· Terminate cables of telephone services
Ans: Satellite closet
· Station to private exchange
Ans: Local station
· Amplitude demodulator
Ans: Diode detector
· Maximum FM deviation audio modulation for TV
Ans: 25 kHz
Post a Comment