Description : Which of the following is not a way of minimizing if not eliminating noise? A. Use redundancy B. Increase transmitted power C. Reduce signaling rate D. Increase channel bandwidth
Last Answer : D. Increase channel bandwidth
Description : Sources of impulse noise induced in communication channels. A. Erroneous digital coding bit caused by an error on a transmission facility B. Transients due to relay operation C. Crosstalk from dc signaling systems D. All of these
Last Answer : D. All of these
Description : An interfering current in a telegraph or signaling channel due to telegraph or signaling current by another channel. A. Crosstalk B. Noise current C. Crossfire D. Intermodulation
Last Answer : C. Crossfire
Description : ____________ is the out-of-band signaling between toll central offices (Bell System Standard) A. 2,000 Hz B. 800 Hz C. 3,835 Hz D. 3700 Hz
Last Answer : D. 3700 Hz
Description : In ISDN, what is the basic access B channel data rate? A. 32 kbps B. 64 kbps C. 144 kbps D. 16 kbps
Last Answer : B. 64 kbps
Description : The word length of Micro computers lies in the range between ________ (A) 8 and 16 bits (B) 8 and 21 bits (C) 8 and 24 bits (D) 8 and 32 bits
Last Answer : (D) 8 and 32 bits
Description : For a space wave transmission, the radio horizon distance of a receiving antenna with a height of 64 meters is approximately A. 8 km B. 32 km C. 64 km D. 256 km
Last Answer : B. 32 km
Description : A radio communications link is to be established via the ionosphere. The maximum virtual height of the layer is 100 km at the midpoint of the path and the critical frequency is 2 MHz. The distance between stations is 600 ... optimum working frequency? A. 6.32 MHz B. 2.1 MHz C. 5.4 MHz D. 1.8 MHz
Last Answer : C. 5.4 MHz
Description : The standard ASCII A. is version II of ASC B. is used only in US and Canada C. has 132 characters including 32 control characters D. is subset of 8-bit EBCDIC code
Last Answer : C. has 132 characters including 32 control characters
Description : What is quadrature quantity?
Last Answer : When the phase angle between two vectors is 90° electrical, then they are said to be quadrature quantity.
Description : Quadrature amplitude modulation(QAM) isa combination of ___________. A) ASK and FSK B) ASK and PSK C) PSK and FSK D) none of the above
Last Answer : ASK and PSK
Description : A constellation diagram shows us the __________ of a signal element, particularly when we areusing twocarriers (one in-phase and one quadrature). A) amplitudeand phase B) amplitudeand frequency C) frequencyand phase D) none of the above
Last Answer : amplitudeand phase
Description : Time synchronization is necessary in (A) FDM. (B) TDM. (C) WDM. (D) Quadrature multiplexing
Last Answer : (B) TDM.
Description : How is a quadrature detector changed when used for phase demodulation?
Last Answer : The quadrature grid signal is excited by a reference from the transmitter.
Description : What condition must exist on both the limiter and quadrature grids for current to flow in a gated-beam detector?
Last Answer : Both grids must be positively biased
Description : The purpose of the series quadrature windings in an Amplidyne - a) Neutralize the effect of Armature Reaction b) Reduce commutation difficulties c) Increase the gain d) Increase the response time
Last Answer : The purpose of the series quadrature windings in an Amplidyne - Increase the gain
Last Answer : In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be out of phase by 90°.
Description : What is the typical number of bits in a static memory location? A. 1 B. 2 C. 16 D. 8
Last Answer : D. 8
Description : You are measuring noise at a -6 dB level point, using the Lenkurt 601A, F1A weighting network, and a flat meter. The meter reading is -59 dBm. This is _________ dBa0. A. 24 B. 12 C. 23 D. 32
Last Answer : D. 32
Description : You are measuring noise in a voice channel with a Lenkurt 601A, F1A weighting network and a flat meter. Your meter reads -47dBm. What is this reading in dBa? A. 77 dBa B. 35 dBa C. 38 dBa D. 32 dBa
Last Answer : C. 38 dBa
Description : Standard design reference for environmental noise temperature. A. 300 K B. 290 K C. 32 ˚F D. 212˚F
Last Answer : B. 290 K
Description : What is the intensity of the magnetic field at the earth’s north pole? A. 32,000 nT B. 62,000 nT C. 32,000 µT D. 62,000 µT
Last Answer : B. 62,000 nT
Description : What is the approximate intensity of the magnetic field at the earth’s surface? A. 32,000 nT B. 62,000 nT C. 32,000 µT D. 62,000 µT
Last Answer : A. 32,000 nT
Description : You are measuring noise in a voice channel at 7 dB test point level. The meter reads -56 dBm (FIA weighted). What is the reading in dBrnc? A. 20 B. 32 C. 35 D. 25
Last Answer : C. 35
Description : What is the data rate of the ISDN Basic access B channel? A. 192 kbps B. 32 kbps C. 64 kbps D. 144 kbps
Last Answer : C. 64 kbps
Description : The signal in a channel is measured to be 23 dB while noise in the same channel is measured to be 9 dB. The signal to noise ratio therefore is __________. A. 9/23 B. 23/9 C. 32 dB D. 14 dB
Last Answer : D. 14 dB
Description : ________ dispersion is caused by the difference in the propagation times of light rays that take different paths down a fiber. a. Material dispersion b. Wavelength dispersion c. Modal dispersion d. Delay dispersion
Last Answer : c. Modal dispersion
Description : The ________ angle measures the satellite position clockwise from the direction of true north. A. azimuth B. elevation C. depression D. critical
Last Answer : A. azimuth
Description : Reading a 58 dBrn, at a +7 test point is equal to ________ dBa0. A. 26 B. 65 C. 51 D. 46
Last Answer : D. 46
Description : ________ is an electric noise produced by thermal agitation of electrons in conductor and semiconductor. A. External noise B. Internal noise C. Thermal noise D. Flicker
Last Answer : C. Thermal noise
Description : Noise always affects the signal in a communications systems at the ________. A. transmitter B. channel C. information source D. destination
Last Answer : B. channel
Description : ________ is a standard whereby mobile phones can gain access to specially tailored Internet websites. A. Bluetooth B. GPRS C. WAP D. EDGE
Last Answer : C. WAP
Description : ________ is the method of encoding audio signals used in US standard 1544 kbit/s 24 channel PCM systems. A. Shannon’s law B. A-law C. Newton’s law D. Mu-law
Last Answer : D. Mu-law
Description : ________ generates light beam at a specific visible frequency. A. Glass fiber B. Infrared C. Light waves D. Laser
Last Answer : D. Laser
Description : An electromagnetic wave is ________ polarized when the electric field lies wholly in one plane containing the direction of propagation. A. Horizontally B. Linearly C. Circularly D. Vertically
Last Answer : B. Linearly
Description : TV channels 2, 4 and 5 are known as ________. A. Mid band UHF B. Low band UHF C. High band VHF D. Low band VHF
Last Answer : D. Low band VHF
Description : Sound intensity level is ________. A. 10 log I/I(ref) B. 10 log I(ref)/I C. 30 log I/I(ref) D. 20 log I/I(ref)
Last Answer : A. 10 log I/I(ref)
Description : One (1) Erlang is equal to ________. A. 360 CCS B. 100 CCS C. 36 CCS D. 3.6 CCS
Last Answer : C. 36 CCS
Description : The random and unpredictable electric signal from natural causes, both internal and external to the system is know as ________. A. Distortion B. Noise C. Attenuation D. Interference
Last Answer : B. Noise
Description : ________ sets a limit on the maximum capacity of a channel with a give noise level. A. Hartley theorem B. Shannon-Hartley theorem C. Nyquist theorem D. Shannon theorem
Last Answer : B. Shannon-Hartley theorem
Description : Troposheric scatter uses the frequencies in the ________ band. A. VLF B. UHF C. VHF D. UF
Last Answer : B. UHF
Description : The standing wave ratio is equal to ________ if the load is properly matched with the transmission line. A. 1 B. 50 C. 10 D. 2
Last Answer : A. 1
Description : The different angles of entry of light into an optical fiber when the diameter of the core is many times the wavelength of the light transmitter is known as ________. A. refraction B. sensor C. mode D. emitter
Last Answer : C. mode
Description : Both frequency and phase modulation utilize ________ modulation A. Phase B. AM and FM C. Digital D. Angle
Last Answer : D. Angle
Description : When one stations is designated as master and rest of the stations are considered slaves message handling is ________. A. polling B. WAN C. LAN D. OSI
Last Answer : A. polling
Description : ECE Board Exam March 1996 According to the Nyquist theorem, the sampling rate that can be used in a PCM system is ________ the highest audio frequency. A. once B. eight times C. twice D. thrice
Last Answer : C. twice
Description : ECE Board Exam March 1996 When the transmitting and receiving antennas are in line-of-sight of each other, the mode of propagation is ________ wave. A. space or direct B. ground C. surface D. sky
Last Answer : A. space or direct
Description : ECE Board Exam March 1996 The characteristics impedance of a transmission line does not depend upon its ________. A. conductor spacing B. conductor diameter C. length D. conductor radius
Last Answer : C. length
Description : When a voltage of 124 VDC is applied to the illustrated circuit with a resistance of 32 ohms the current will be ________. EL-0018 A. 0.258 amps B. 3.875 amps C. 8.258 amps D. 156 amps
Last Answer : Answer: B
Description : Slow down, if necessary stop, make sure that a railway vehicle is approaching. It is always necessary to stop and only pass through the rails with due care.
Last Answer : Slow down and, if necessary, stop to make sure the vehicle is approaching.