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1. ECE Board Exam April 1997 What is the impedance of a balance 4-wire with a diameter of 0.25 cm and spaced 2.5 cm apart

using an insulator with a dielectric constant of 2.56?

A. 100 Ω

B. 65 Ω

C. 75 Ω

D. 50 Ω

2. ECE Board Exam April 1997

What is the impedance in ohms of a transformer marked for 25V, 4W, when the secondary is

correctly loaded?

A. 150 Ω

B. 156 Ω

C. 160 Ω

D. 165 Ω

3. ECE Board Exam April 1997 A single conductor running from the transmitter to the antenna.

A. RG-8/U

B. Single line wire

C. Twin-lead

D. MIcrostrip


If voltage change equal to twice its original value, what is its corresponding change in dB?

A. 9 dB

B. 6 dB

C. 10 dB

D. 3 dB


To couple a coaxial line to parallel line, it is better to use a ______.

A. Slotted line

B. Quarter-wave transformer

C. Directional Coupler

D. Balun

6. ECE Board Exam April 1997 What is the characteristic impedance of a single wire with a diameter d= 0.25 mm placed at the

center between grounded parallel planes separated by 1 mm apart. The wire is held by a material

with a velocity factor of 0.75.

A. 85 Ω

B. 63 Ω

C. 50 Ω

D. 75 Ω


If you have available number of power amplifiers with a gain of 100 each, how many such

amplifiers do you need to cascade to give an overall gain of 60 dB?

A. 3

B. 4

C. 5

D. 2


________ 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

9. ECE Board Exam April 1997 Transmission sent in both directions simultaneously.

A. Full duplex

B. Duplex

C. Half duplex

D. Simplex


Industrial noise frequency is between _________.

A. 200 to 3000 Mhz

B. 15 to 160 Mhz

C. 0 to 10 Khz

D. 20 Ghz


Reference noise temperature.

A. 70 deg F

B. 30 deg C

C. 290 Kelvin

D. 25 deg C


What is the reference frequency of CCITT psophometric noise measurement?

A. 800 Hz

B. 1500 Hz

C. 3400 Hz

D. 1000 Hz


Which does not effect noise in a channel?

A. None of these

B. Bandwidth

C. Temperature

D. Quantizing level


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


The most common unit of noise measurement in white noise testing.

A. dBw

B. dBk

C. dBm

D. NPR


Unit of noise power of psophometer

A. dBa

B. pWp

C. dBm

D. dBmO


100% modulation in AM means a corresponding increase in total power by:

A. 25%

B. 75%

C. 100%

D. 50%


If the modulation index of an AM wave is doubled, the antenna current is also doubled, the AM

system being used is

A. A5C

B. A3J

C. A3H

D. A3


What particular circuit that rids FM of noise?

A. HPF

B. Phase shifter

C. Limiter

D. LPF


What is the advantage of PTM over PAM?

A. Simpler to generate

B. Low sampling rate is required

C. Much better noise immunity

D. All of these


At 100% modulation, the sum for the effective voltages in both sidebands is equal to ______%

of the unmodulated carrier voltage.

A. 50

B. 71

C. 100

D. 25


A carrier signal has ______.

A. Constant peak amplitude

B. The information

C. Frequency range 20-20000 Hz

D. A varying amplitude


Which transmit only one sideband?

A. A3E

B. 3AJ

C. 11BE

D. H3E


The final amplifier of either FM or AM transmitter operates as

A. Class B

B. Class C

C. Class A

D. Class D


Modulation means

A. Varying of information

B. Utilization of a single transmission channel to carry multiple signals

C. Varying of some parameters of a carrier such as its amplitude to transmit information

D. Transmit pulses in DC form on a copper wire


What is the advantage of sidetone?

A. High transmission efficiency

B. Results to a strengthened signal

C. No energy dissipation

D. Assures that the telephone is working


The standard test tone

A. 0 dB

B. 10 dBm

C. 0 dBm

D. 10 dB


One (1) Erlang is equal to ________.

A. 360 CCS

B. 100 CCS

C. 36 CCS

D. 3.6 CCS


Transmission of printed material over telephone lines.

A. Video text

B. Facsimile

C. Encoding

D. Xerox copy


1-CCS is equal to?

A. 60

B. 100

C. 600

D. 1


1 Erlang is ______.

A. 1000 TU

B. 10 TU

C. 100 TU

D. 1 TU


When waves bend away from straight lines of travel, it is called _________.

A. Refraction

B. Reflection

C. Rarefaction

D. Diffraction


Highest frequency that can be used for skywave HF communications between two given points

on earth.

A. Gyro frequency

B. Maximum usable frequency

C. Critical frequency

D. Virtual frequency


Electromagnetic radiation theory was profounded by ______.

A. Sir Edward Appleton

B. Sir Isaac Newton

C. James Clerk Maxwell

D. Michael Faraday

35. ECE Board Exam April 1997 Type of transmission path that permits communication in the frequency range from 30 to 60

MHz and over distances form about 1000 to 2000 km.

A. Ducting

B. Ionospheric scatter

C. Microwave

D. Troposcatter


What is the thickest layer of the ionosphere?

A. E

B. F1

C. F2

D. D


Distance traveled by a wave in the time of one cycle.

A. Hop

B. Frequency

C. Wavelength

D. Crest


Which region of the ionosphere is mainly responsible for long distance night time

communication?

A. A layer

B. D layer

C. E layer

D. F layer


What is the effective earth’s radius when N = 300?

A. 8500 km

B. 6370 km

C. 7270 km

D. 7950 km


The polarization of a discone antenna is _____.

A. Horizontal

B. Vertical

C. Omni

D. Directional


_______ is the horizontal pointing angle of an antenna.

A. Right angle

B. Angle of elevation

C. Bandwidth

D. Azimuth


Which is properly terminated antenna?

A. Rhombic

B. Hertz

C. Marconi

D. Dipole


______ is a device that detects both vertically and horizontally polarized signals simultaneously.

A. Crystal

B. Orthomode transducer

C. Light transducer

D. Optoisolator


How much does the radiated power of an antenna increases if its current increased by 3.3 times?

A. 6.6 times

B. 3.3 times

C. 10.89 times

D. 9.9 times


What do you call the energy that was not radiated into space or completely transmitted?

A. Incident waves

B. Captured waves

C. Standing waves

D. Modulated waves


What is the estimated medium wind loading in the Philippines for antenna tower design?

A. 200 kph

B. 250 kph

C. 300 kph

D. 100 kph


The minimum number of turns a helix antenna must have.

A. 4

B. 5

C. 3

D. 6


When testing transmitter to prevent interfering with other stations, which type of antenna must

be used?

A. Dummy antenna

B. Hertzian antenna

C. None of these

D. Void antenna


A device that radiates electromagnetic energy and or intercepts electromagnetic radiation.

A. Antenna

B. Transmitter

C. Transmission line

D. Transceiver


The frequency of operation of a dipole antenna cut to length of 3.4 m.

A. 42.9 MHz

B. 61.3 MHz

C. 38.5 MHz

D. 53.5 MHz


Full duplex transmission means

A. One way transmission

B. 24-hour transmission

C. Broadcast transmission

D. Two-way simultaneous transmission


Transmission system for a multidrop network

A. Taken passing

B. Polling

C. Switching

D. CSMA/CD


Synchronous modems cost more than asynchronous modem because _______.

A. They have larger bandwidth

B. They are larger

C. The production volume is larger

D. They have clock recovery circuits


What equation defines the composition of an ISDN basic access line?

A. B+2D

B. B+D

C. 2B+2D

D. 2B+D


Modem is referred to as ______.

A. Universal asynchronous Rx/Tx

B. Data communication equipment

C. Universal synchronous Rx/Tx

D. Data terminal equipment


_______ character signifies the start of the test for Bisync.

A. STX

B. ETX

C. SOH

D. BCC


What is the reason why companding is employed in PCM systems?

A. To overcome impulse noise in PCM receivers

B. To allow amplitude limiting in the receivers

C. To solve quantizing noise problem

D. To protect small signals in PCM from quantizing distortion


What is framing?

A. Is concerned of synchronous system

B. Refers to parallel transmission

C. Is concerned with the boundaries between characters

D. Is concerned with individual bits


The method of determining the bandwidth of any processing system is ______.

A. Bandwidth analysis

B. Frequency spectrum

C. Spectral analysis

D. Frequency analysis


It is a protocol used to connect the other packet witching network.

A. X.25

B. X.50

C. X.10

D. X.75


Slowest communications hardware product.

A. Synchronous

B. Asynchronous

C. Ethernet

D. Internet


Highest theoretical frequency that can be processed at a sampling rate without aliasing.

A. Folding frequency

B. Resonant frequency

C. Natural frequency

D. Critical frequency


Data is directly on the transmission cable.

A. Asynchronous

B. Synchronous

C. Baseband

D. Broadband


A source code whose average word length approaches the fundamental limit set by the entropy

of a discrete memory less source.

A. Prefix code

B. Huffman code

C. Entropy code

D. Source code


______ sets the limit on the maximum capacity of a channel with a given noise level.

A. Hartley theorem

B. Shannon-hartley theorem

C. Nyquist theorem

D. Shannon theorem


Gateway can interconnect LANs that have ____ protocols and formats.

A. The same

B. Different or the same

C. Totally different

D. None of these


Steps to follow to produce PCM signal.

A. Quantizing, sampling, and coding

B. Sampling, quantizing, and coding

C. Sampling, coding and quantizing

D. Coding, quantizing and coding


Transmission sent in both directions simultaneously.

A. Full duplex

B. Duplex

C. Half duplex

D. Simplex


_______ detects the satellite signal relayed from the feed and converts it to an electric current,

amplifies and lower its frequency.

A. Feedhorn

B. Satellite dish

C. Satellite receiver

D. LNB


What kind of battery panels are used in some advance satellites?

A. Gallium Arsenide solar panel

B. Germanium based panels

C. Silicon based panels

D. Gallium Phosphate solar panel


Footprint refers to coverage area in the globe

A. Satellite radiation polarization

B. Satellite navigation

C. Satellite radiation pattern

D. Satellite coverage


Asia Sat I covers how many countries in Asia?

A. 38

B. 40

C. 44

D. 42


Insertion loss of connector-type splices for a single-mode fiber cable.

A. 0.2 dB

B. 0.3 dB

C. 0.09 dB

D. 0.38 dB


A non-coherent light source for optical communications system.

A. PIN Diode

B. ILD

C. APD

D. LED


Type of fiber that has the highest modal dispersion

A. Step-index multimode

B. Step-index single mode

C. Graded index mode

D. Graded index multimode


Fiber optic cable operates near _______ frequencies.

A. 800 THz

B. 20 MHz

C. 200 MHz

D. 2 GHz


Lifetime of ILD’s

A. 150,000 h

B. 100,000 h

C. 50,000 h

D. 200,000 h


The sound energy per unit area at right angles to the propagation direction per unit time.

A. Sound intensity

B. Loudness

C. Coherence

D. Sound stress


_______ is the transmission of sound from one room to an adjacent room thru common walls,

floors or ceilings.

A. Reverberation

B. Refraction

C. Flanking transmission

D. Reflection


The sound power level of a jet plane flying at a height of 1 km is 160 dB. What is the maximum

sound pressure level on the ground directly below the plane assuming that the aircraft radiates

sound equally in all directions?

A. 59.1 dB

B. 69.1 dB

C. 79.1 dB

D. 89.1 dB


Lowest frequency produced by a musical instrument.

A. Fundamental

B. Midrange

C. Period

D. Harmonic


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)


Tendency of sound energy to spread.

A. Reflection

B. Diffraction

C. Rarefaction

D. Refraction


______ used to measure speech volume

A. Volume meter

B. Audio frequency meter

C. Volume unit meter

D. Speech meter


What is the local oscillator frequency range commercial AM broadcast if it is equal to 455 KHz.

A. 540 to 1600 KHz

B. 0 to 1600 KHz

C. 995 to 2055 KHz

D. 0 to 455 KHz


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


______ is the first component of any MATV system to received broadcast signals.

A. Receiver

B. Antenna

C. Filter

D. Transmitter


Mechanism or device which enables the TV camera to move in internal and tilting motion.

A. Tilting

B. Scanner

C. Pan/tilt device

D. Panning device


The allowable deviation ratio of commercial FM broadcast.

A. 25

B. 15

C. 5

D. 75


______ is the time duration for one horizontal trace.

A. 48µs

B. 52 µs

C. 62 µs

D. 50 µs


Which is atmospheric attenuation?

A. Attenuation due to rain

B. Attenuation due to other gasses

C. Attenuation due to mist and fog

D. Due to water vapor and oxygen


A microwave system that requires the use of repeater.

A. Intervening terrain is favorable

B. Distances involved are greater

C. The required reliability is met

D. All of these


What frequency does oxygen causes excessive attenuation

A. 119 GHz

B. 183 GHz

C. 310 GHz

D. 60 GHz


RADAR means

A. Radio detection and rating

B. Radio detection and ranging

C. Radio distance and ranging

D. Radio delay and ranging


A microwave link between the earth station and the down-town terminal.

A. STL

B. Uplink

C. Downlink

D. Terrestrial link


The advantage of periscope antenna in microwave

A. Minimize interference to and from other neighboring stations

B. Shorten waveguide link

C. Reduce tower height

D. All of these


Professional Regulations Commission was created under ______.

A. PD 323

B. PD 223

C. PD 232

D. RA 223


The institutionalization of the continuing Professional Education (CPE) Program of the various

regulated profession under the supervision of the Professional Regulation Commission.

A. E.O. No. 266

B. E.O. No. 626

C. E.O. No. 662

D. P.D. 381


The basic law providing for the regulation of radio station, communications in the Philippines

and other purposes.

A. Act. No.`3846

B. D.O. No. 11

C. D.O. No. 88

D. D.O. No. 5


Listing of the date and time events, programs , equipment, test, malfunctions and corrections in

communication system.

A. File

B. Documentation

C. Reporting

D. Log

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