Communications Engineering Coaching Materials: Section 3 Module 2

This is the Section 3 Module 2 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 2

· Regulates the use of frequency spectrum and electronic communication in the Philippines

Ans: NTC

· Largest category of electronics

Ans: Computer

· 2^nd largest category of electronics

Ans: Communications

· 3^rd largest category of electronics

Ans: Control

· Graphical transmission other than TV

Ans: videotext, teletex, facsimile

· Difference of audio and sound for negative transmission

Ans: 4.5 MHz

· VSWR when terminated at Zo

Ans: 1

· Wires that are in a fire proof ceiling

Ans: Poke through

· Oldest form of modulation

Ans: AM

· Simplest detector

Ans: Diode detector

· Most common cause of internal noise

Ans: Thermal agitation

· Vary the DC voltage to vary the gain

Ans: Dual gate MOSFET

· vary the collector current to vary the gain

Ans: BJT

· Ceiling and visible area of VFO operating zone

Ans: 3048 – 4827 mi

· A feedback that is used to eliminate drift frequency

Ans: frequency control oscillator

· Rectangular hole on the floor

Ans: Slot

· Increase gain

Ans: decrease beamwidth

· F connector

Ans: RG58U

· It is used as mixer (simplest)

Ans: Resistor

· Insertion loss of fiber optics

Ans: 0.38 dB

· A tap used in subscriber drop line

Ans: high tap loss

· Cladding of graded index multimode fiber

Ans: 0.05 nm

· No cladding

Ans: Laser

· Wide beam of missile guidance radar

Ans: Wide beam

· SSB generation

Ans: filter method

· It is used in filter method

Ans: Quartz crystal

· Suppressed carrier

Ans: balanced modulator

· Cheap filter method

Ans: Ceramic filter

· Highest Sound absorption

Ans: Celotex

· PBX

Ans: Star topology

· Hierarchal topology

Ans: SNA

· Generator code of CDMA

Ans: PSN generator

· Open ended slot antenna

Ans: Notch antenna

· 1544 kbps and 24 VB ch

Ans: u-law

· Decay of TV receiver

Ans: 5 ms

· Most positive TV

Ans: 2^nd anode

· Common dispersion in fiber optic

Ans: Absorption and Rayleigh scattering

· Popcorn noise

Ans: Burst noise

· Theoretical distance of WiMax

Ans: 50 km

· Practical distance of WiMax

Ans: 3 – 5 mi

· Bit rate of Bluetooth

Ans: 2.402 – 2.480 Mbps

· CDPD

Ans: Cellular Digital Packet Data

· Data rate of CDPD

Ans: 19.2 Mbps

· Modulation technique of CDPD

Ans: GMSK

· MPEG7

Ans: Multimedia Content Description Interface

· MPEG3

Ans: Motion Pictures Experts Group 1, Audio Layer 3

· Ribbon microphone is ___ microphone

Ans: Pressure-gradient

· Time for V scan line

Ans: 1333 us

· Under water pressure level sensor

Ans: Hydrophone

· Used for error detection

Ans: XMODEM

· Discriminator on secondary detector

Ans: Doppler radar

· Father of internet

Ans: Vinton Cerf

· Weak RGB

Ans: Gray

· Strongest signal color

Ans: Yellow-green

· I signal phase

Ans: 57°

· GPS

Ans: 1978

· Angle of trust wind parabolic antenna

Ans: 56°

· GPS inclination angle

Ans: 55°

· H scan line

Ans: 10.2 us

· Fiber optic frequency near ___

Ans: 800 THz

· Demodulate PCM use

Ans: low pass filter

· Diode detector uses

Ans: Rectification and filtering

· Bandpass filter

Ans: IF amplifier

· Turnstile antenna to feed 2 signals in 1 antenna

Ans: Circulator

· Code 39

Ans: Discrete Code

· Types of Discriminator

Ans: PLL, Foster Seeley, Quadrature

· Not primary superheterodyne receiver

Ans: RF amplifier

· 2 oscillator

Ans: Black and White

· Shadow mask

Ans: 300,000 holes

· CRT capacitance

Ans: 2000 pF

· Noise margin of Optical fiber

Ans: 5 to 10 dB

· Margin of safety

Ans: Power margin

· Bluetooth standard

Ans: IEEE 802.15

· IEEE 802.15.4

Ans: Zigbee

· Data rate of WiMax

Ans: 11-54 Mbps

· Under the influence of inductance field

Ans: near field

· Most dense at night

Ans: F layer

· Sound corresponds to color of light

Ans: Pitch

· All waves absorbed and reflected

Ans: Labertian reflection

· Reflects one color and rejects other

Ans: dichroic

· Matrix

Ans: Combination circuit TV

· FM luminance frequency for VCR recording

Ans: 3.5 MHz

· Control frequency of VCR1

Ans: 30 Hz

· Lowest layer for HF propagation

Ans: C layer

· λ/2 150 MHZ at ___

Ans: 1 meter

· UHF connector to coax

Ans: PL259

· RS232C has

Ans: 25 pins

· 3G slow

Ans: 384 kbps

· 3G fast

Ans: 144 kbps

· 3G stationary

Ans: 2 Mbps

· ILD disadvantage

Ans: temperature dependent

· Reference noise temperature

Ans: 290 K

· 10BASET cable, T means

Ans: type of cable used

· Convolution

Ans: Trellis coding

· MPEG 2 uses

Ans: Cosine transform

· Disadvantage of fiber optic cable

Ans: Cable splicing and simplicity

· Flutter echo

Ans: Successive echo

· Telegraph consists of ___ characters plus word space

Ans: 7 ½

· Above 10 Hz jitter

Ans: wander

· Telephone wire

Ans: AWG 19

· Interhost

Ans: Session layer

· Measurement of height of ionosphere

Ans: Ionosonde

· PEP

Ans: 1/3 to ¼

· IF Sound carrier cable

Ans: 45.75 MHz

· Connector TV at VCR lowest cost

Ans: F-7 connector

· Elliptical

Ans: Gregorian fed

· Resonant antenna

Ans: Marconi

· When the main lobe of the array pattern is perpendicular to the array axis, the uniform linear array elements is known as

Ans: Broadside array

· When the main lobe of the array pattern lies along the array axis, the uniform linear array elements is known as

Ans: end-fire array

· What is non-continuous noise of irregular pulses or spikes of short duration with high amplitudes?

Ans: Jitter

· Strowger switch

Ans: 1897

· Cause of attenuation

Ans: Walls of waveguide

· 480 pixel progressive format

Ans: 640 x 480

· HDTV has ___ more information

Ans: 5

· Video specification used for video compression

Ans: MPEG4

· Formula for S/N above 240 channels

Ans: S/N = 4.47 d (( -15 + 10 log N )/20)

Where: d = 200 kHz

· Formula for S/N below 240 channels

Ans: S/N = 4.47 d (( -1 + 4 log N )/20)

Where: d = 35 kHz

· pWp

Ans: pWp = 0.56 log^-1 ((90 – S/N)/( 10 ))

· Flat pWp

Ans: pWp = log^-1 ((90 – S/N)/( 10 ))

· Kr TE₁₀

Ans: kr = 3.83

· Kr TE₁₁

Ans: kr = 1.84

· Klystron factor

Ans: k = fo/(2(n+1)(1+2Vo))

· Mode

Ans: mode = n +(3/4)

· Formula

Ans: 10 log (n_g+n_i)²/(n_g-n_i)

· Relative permittivity of PVC

Ans: 3.3

· Relative permittivity of polyethylene

Ans: 2.27

· NTSC

Ans: 0.7 N_L

· PAL

Ans: 0.8N_L

· Effective noise bandwidth

Ans: BW_eff = (π/2)(BW_3dB)

· Parabolic antenna gain with respect to beamwidth

Ans: G (dB) = 10 log (203/φ)²

· Beamwidth

Ans: φ = 203/(√10)^G(dB)/10

· Five wire line

Ans: Zo = 173 /√ξr log D/0.933 d

· Balanced line between grounded parallel planes

Ans: Zo = 173/√ξr log ( 4h tanh (πD/2h)/ πd )

· Number of modes fiber optic

Ans: M = 0.5 (πD NA/λ)²

· Q of SSB

Ans: Q = fo (log ^-1 dB/20)^1/2 /4Δfi

· Reliability based on propagation

Ans: U_ndp = abf_GHz^1.5 d_mi³ (1.25 x 10^-6)10^-FM/10

R = (1- U_ndp) x 100%

· Reliability based on equipment failures

Ans: U = Outage time in hours/year / 8760 hours

· Earth’s curvature

Ans: EC = d₁d₂ / 1.5k

Complete List of Communications Engineering Coaching Materials

Communications Engineering Coaching Materials

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