Communications Engineering Coaching Materials: Section 3 Module 3

(Last Updated On: December 8, 2017)

This is the Section 3 Module 3 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 3

· Absorption coefficient

Ans: α = δa/S

δa = (55.3 V/v)(1/t1 – 1/t2)

· Effective noise BW parallel tuned circuit

Ans: BWeff = 1/(4RpC)

· Reject a single color and allow other colors

Ans: Dichroic

· Hertz antenna used above

Ans: 2MHz

· Elliptical reflector

Ans: Gregorian Fed

· Used in LOS transmission

Ans: VHF

· Used in submarine applications

Ans: ELF

· Used in marine and aeronautical communications

Ans: L-band

· Lowest attenuation fiber optic length

Ans: 1000 ft

· Longest wavelength

Ans: Orange

· Results from the combination of weak blue, red and green

Ans: Gray

· Electron gun goes straight to the picture tube

Ans: Green

· Protocol which uses checksum as error detection scheme

Ans: XMODEM

· Video specification used for video compression

Ans: MPEG4

· Used in European Cordless Telephone

Ans: GFSK

· Microwave telephone via satellite

Ans: Arthur Clarke

· Foundation of acoustic theory in buildings

Ans: Wallace Sabine

· Father of Internet

Ans: Vinton Cerf

· Chrome type cassette tape

Ans: Type 2

· Protection from snow and wind

Ans: Radome

· Daytime ; reflect low frequencies, absorb medium frequencies

Ans: Layer

· Most dense

Ans: F2 layer

· transequatorial propagation

Ans: best in afternoon and early evening

· Aspect ratio of HDTV

Ans: 16:9

· Without bottle necks

Ans: Mesh

· 480 pixel format

Ans: 640 x 480 pixel progressive

· Lifetime of LED

Ans: 200,000 hrs

· Number of holes in shadow mask

Ans: 300,000

· Lead oxide camera tube

Ans: Plumbicon

· Acts as an antenna at high frequencies

Ans: Transmission line

· Reference in dba

Ans: -85 dBm

· Reference temp in noise analysis

Ans: 290 K

· Audible frequency range

Ans: 16 Hz – 16 kHz

· RG62 to avoid reflection use

Ans: 93 Ω

· Used in thick Ethernet

Ans: RG11

· RS232C

Ans: has 25 pins / 20 kbps

· 1 supergroup

Ans: 75 groups

· Heating voltage of TV picture tube

Ans: 6.3 V

· Wi-Fi

Ans: 11-54 Mbps

· WiMax theoretical range

Ans: 50 km

· WiMax practical range

Ans: 3 to 5 miles

· 1 jumbogroup

Ans: 3600 VC

· Bluetooth

Ans: IEEE 802.15

· WiMax

Ans: IEEE 802.16

· Zigbee

Ans: IEEE 802.15.4

· Angular separation between half-power points

Ans: Beamwidth

· Prevent FM from entering

Ans: Diplexer

· Not temperature dependent

Ans: ILD

· Color subcarrier

Ans: 3.58 MHz

· Highest absorbent coefficient material

Ans: Celotex

· Glass

Ans: highest optical characteristics ; lowest attenuation

· PCS fiber optic

Ans: glass core

· Glass

Ans: lower velocity than air

· Glass

Ans: has lower index of refraction than water

· Sound is absorb on walls

Ans: Anechoic

· Cause of attenuation

Ans: Walls of waveguide

· Bending of light from high density to low density

Ans: Refraction

· Adjustment used by means of loudspeaker feedback system

Ans: Ambiophony

· Uses convolutional coding

Ans: Trellis Coding

· Inverter CMOS

Ans: has two transistors

· SSB

Ans: AM

· Uses CSMA/CD ; 10 Mbps

Ans: Ethernet

· Structure which supports cables

Ans: Cable Tray

· GPRS uplink rate

Ans: 14 kbps

· Tunes to a radio frequency

Ans: Local oscillator

· Two PBX

Ans: Tie Trunk

· Hierarchical topology

Ans: SNA

· Types of demodulator :

Ans: PLL, Quadrature and Foster – Selley

· Violet ray

Ans: 4000 Angstrom = 0.4 micron

· Popcorn

Ans: Burst noise

· Used to view the envelop of a modulated signal

Ans: Oscilloscope

· Power output of sideband envelope

Ans: Peak Envelop power

· Disadvantage in using FOC

Ans: Splicing

· Causes distortion on the demodulated signal (delta modulation)

Ans: Slope overload

· Spread spectrum

Ans: DSSS

· Mostly used in satellite communications

Ans: TDMA

· High internal resistance

Ans: Nickel Iron

· Protection against snow and wind loading

Ans: Radome

· Fiber optic performance

Ans: bit rate

· Attenuation expressed in

Ans: dB/um

· UHF connector

Ans: PL259

· CDMA

Ans: no limitation in BW

· Interface reduction

Ans: co-channel

· 2 diff amplitudes, 2-phase

Ans: QAM

· Figure of merit with FSK

Ans: h factor

· OSI layer – buildings

Ans: Novell Network

· Fluctuations

Ans: Fading

· Most common light generator

Ans: ILD

· Lifetime of LCD

Ans: 200,000 years

· BFO of SSB

Ans: Carrier oscillator

· Frequency hopping, assign diff carrier frequency

Ans: CDMA

· Antenna complete in itself and self-oscillating

Ans: Hertz Antenna

· Unique binary code for CDMA satellite

Ans: Chip code

· Output of magnetic microphone

Ans: 1 mV

· 350-440 Hz

Ans: call-waiting tone

· Connect telephone

Ans: Induction coil

· Conduit, reduce abreaction

Ans: Bashing

· Most reliable for error detection

Ans: CRC

· Use 2 mixers, filter & phase-shift

Ans: Balanced modulator

· 1% left in the TV

Ans: Screen persistence

· Unconscious level heard by human ear

Ans: 6-10 dB

· Microwave range of frequency

Ans: Window

· Marginal safety for microwave

Ans: 5 – 10 dB

· Luminance FM for VCR

Ans: 2.5 MHz

· Non-directional horizontally polarized

Ans: VHF & UHF

· Stereo pilot carrier

Ans: 19 kHz

· Dipole resistance

Ans: 73 ohms

· RG-65

Ans: 93 Ω

· Complex pressure amplitude over complex amplitude volume

Ans: Acoustic impedance

· Optical density

Ans: Radiant flux

· HDTV

Ans: 16:9

· Calls not satisfied

Ans: Erlang C

· PBX

Ans: Star topology

· Blanking pulse of negative

Ans: 75%

· Beginning & end of the char code

Ans: Character Synchronization

· Improve AM broadcast timer

Ans: Counterpoise

· Visible signal

Ans: Infrared

· Variations in signal strength by atmospheric conditions

Ans: Fading

· For abrasion

Ans: Abrasion

· Known for power amplification

Ans: Class A

· Injection laser diode

Ans: APD

· 1st radio receiver

Ans: Crystal

· Communication for vehicle, ground

Ans: Marconi

· Visible wavelength

Ans: 0.4 to 0.8 micron

· Radiation direction

Ans: End fire array

· IMPATT

Ans: 30 GHz

· Logic network in form of an array

Ans: Matrix

· Across resistor

Ans: Shot noise

· Information capacity

Ans: Shannon Hartley theorem

· Divide digital data

Ans: Converter

· Sum of minterm & product of maxterm

Ans: Canonical

· Handset local loop

Ans: Induction coil

· Figure of merit in light

Ans: Numerical aperture

· All constant

Ans: Diatonic

· Purity of color

Ans: Q & I amplitude

· Maximum brightness

Ans: 50% Red 59% Green and 11% Blue

· Handshaking principle

Ans: Delta modulation

· Handshaking principle

Ans: Synchronous

· Error correction at high frequency

Ans: ARQ

· Unicode

Ans: 16 bit long

· High frequency AM

Ans: PIN diode

Complete List of Communications Engineering Coaching Materials