Comms Coaching•
ISDN basic rateAns: 2B+2D
Access B data rateAns: 64 kbps
Maximum diameter of fiberAns: rmax = 0.383λ NA
V numberAns: V = πdNA λo
Neutralization isAns: Elimination of RF signals
An IC of differential amplifier and on-chipAns: NE602
Distance of microwave repeater of fiber opticAns: 6.215 – 18.65 mi
IF up and down converterAns: 70 MHz
Height of GLONASSAns: 19100 km
Accuracy of GPSAns: 2 nautical miles
Phase shiftAns: β = √(ωδu/2)
Negative transmission, medium grayAns: 40%
Negative transmission, tip of syncAns: 100%
1
Comms Coaching•
Negative transmission, blanking levelAns: 75%
Negative transmission, blackAns: 67.5%
Negative transmission, maximum whiteAns: 12.5%
Time for horizontal retraceAns: 10.2 us
Path of telephone line crossing a private property and entering a buildingAns: Service entrance
Cable within a building of series of buildingsAns: Building cable
Circular passage of cableAns: Pipe sleeve
Marine radar communicationsAns: X-band
Civil aircraftAns: 30-100 MHz
Aircraft long range communicationsAns: 2 – 30 MHz
Wireless telegraphAns: 1895v
TelegraphAns: 1844
TelephoneAns: 1876
RadioAns: 1887
2
Comms Coaching•
Average splice of fiber opticAns: 0.15 dB
Pilot subcarrier frequencyAns: 19 kHz
A subcarrier set by musicAns: 67 kHz
Travelling wave antennaAns: Rhombic antenna
Brightness or illuminationAns: contrast
Amplitude of the signalAns: Contrast
Out of controlAns: Singing
Frequency above 300 GHzAns: millimeter waves
Micrwave operatesAns: above 1 GHz
Emits heat energyAns: 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 byAns: ITU
Characteristic impedance of coaxial cable3
Comms Coaching•
Ans: 75 Ω
TDM usedAns: PCM
Telemetry dataAns: PCM
Frequency difference of color subcarrier and soundAns: 0.92 MHz
Chroma signalAns: 3.58 MHz
LORAN C frequencyAns: 100 kHz
Which cannot be used for range and bearing?Ans: LORAN C
Ceramic resonator at frequency of 200 – 500 kHzAns: Ceramic filter
Multiple resonant diskAns: Mechanical bandpass filter
Doubley balanced modulators and GaAs filters are best mixers forAns: VHF, UHF and microwave
Layer of ionosphere for nighttime communicationsAns: F layer
Which of the following is true?Ans: Negative polarity has an amplitude decreases when white.
Third letterAns: Type of information to be transmitted
Lock rangeAns: PLL
Critical part of FM receiver4
Comms Coaching•
Ans: Front end
Advantage of superheterodyne receiverAns: excellent sensitivity and stability
Disadvantage of TRFAns: Tuning and selectivity
Ch.4 downlink frequencyAns: 3.84 MHz
λ/4 vertical λ/4 spaced and 90 degrees out of phaseAns: Unidirectional Cardioid
Discone antenna usesAns: Vertical polarization
No gain antennaAns: Isotropic
Token passing Ans: IEEE 804.2
PLL consists ofAns: FM synthesizer and FM demodulator
Simplest AM receiverAns: TRF
MF rangeAns: 300 kHz- 3 MHz
1 pixelAns: 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 signalAns: Frequency multiplier
5
Comms Coaching•
Time constant for pre-emphasis and de-emphasis networkAns: 75 us
To compress voice signal dynamic rangeAns: Companding
Amplifier for PCMAns: Sample and Hold circuit
Cut offAns: Class B
90 degrees to 150 degreesAns: Class C
Benefits of multiplexingAns: Economy
TV picture tube Ans: kinescope
Phase angle in TVAns: hue
Linear amplifierAns: Class A
Transmission rangeAns: TR = (2h)/(tan β)
Frequency of reverberation chamber Ans: f = 125 3√(180/V)
Advantage of FM over AMAns: Noise immunity
Disadvantage of FMAns: Wider bandwidth
Floor area within a building that is usable and rentable6
Comms Coaching•
Ans: Rentable Floor Area
Code for touch tone dialingAns: two-to-seven
Increasing the amplitude level of higher frequency on modulating frequencyAns: Pre-emphasis network
Cable that is entering the buildingAns: Entrance Cable
Comprises of telephone equipment; transmitter/receiver, etc.Ans: Station.
A telephone line that do not serve exchangeAns: Private Line
It is used to connect private branch exchange and central officeAns: Trunk Line
Most widely used fiber optic cableAns: Single mode step index.
Most widely used RF transformerAns: Toroid
Advantages of toroidal coreAns: Fewer turns, Higher Q, and no shielding
Refers to the general (whole) telephone company that serves communicationsAns: Plant
It is used to increase the power level of AM and other sidebandsAns: Class A or B
It does not affect by the RF carrierAns: Phase modulated emission
Time required for the horizontal scanning lineAns: 63.6 us
It must be on during horizontal flyback time7
Comms Coaching•
Ans: Burst separator
Controls the phase angle of modulated color signal in TVAns: Tint
Non-resonant antennaAns: V-antenna
Information on altitude, etc. of an aircraftAns: Air data
End line of communicationAns: Station wiring
Holds wires, they are conduitsAns: Raceway
It contains PBXAns: Equipment room
Line of sight frequencyAns: VHF and UHF
An antenna used for VHF and higher frequencyAns: Omnidirectional antenna
Frequency conversion and translation Ans: Heterodyning
Cable connected to a cross connect terminal and not directly connected to the local exchangeAns: Home cable
Maximum propagation delay of GEOAns: 278 us
Velocity factor of open-wire lineAns: 0.9
Velecoity factor of coaxial lineAns: 0.8
8
Comms Coaching•
Most widely used modulator Ans: Balanced modulator
Multielement system for controlAns: Key system
Narrowband still pictureAns: Slow scan TV
Average power emitted by laserAns: pulse energy x repetition rate
PCM system used in telephone network and uses TDM techniqueAns: Bell T1
Sampling interval of T1 system Ans: 25 us
Widely used TV modulatorAns: Quadrature detector
Cut-off audio output to prevent annoying noiseAns: Squelch
Permits selective signalingAns: CTCS – continuous tone control squelch
Cut-off frequency of pre-emphasis and de-emphasis networkAns: 2122 Hz
Feedback system used to correct the frequency drift of VHF, UHF and microwave frequency receiversAns: AFC (automatic frequency control)
Produces excellent deviation FM for frequencies below 1 MHzAns: IC VCO
Period of visible HAns: 12.5 us
Period of equalizing pulse9
Comms Coaching•
Ans: 2.29 us
Delay of geosynchronous satelliteAns: 278 us
A VCO in which frequency is varied in proportion to the amplitude of modulating DC or AC signalAns: Subcarrier oscillator
All plants which are “out of doors” not inside the buildingAns: Outside plant
All plants located inside the telephone public exchange buildingAns: Inside plant
Used to terminate telephone wire cableAns: Distrubution frame
It is used to terminate floor distribution cableAns: Floor Distribution Terminal
Portion of a floor service by the floor distribution terminalAns: Floor terminal distribution area
Branch cable of various floor used to connect floor distribution terminal to the riser cableAns: Floor distribution cable
Upstream signal frequency of two wire cableAns: 5- 30 MHz
It is found at the BPA of the TVAns: color level control
2 main barrier of communicationsAns: language and distance
Raceway of rectangular cross sectionAns: header or feeder duct
Terminate cables of telephone servicesAns: Satellite closet
10
Comms Coaching•
Station to private exchange Ans: Local station
Amplitude demodulatorAns: Diode detector
Maximum FM deviation audio modulation for TVAns: 25 kHz
Regulates the use of frequency spectrum and electronic communication in the PhilippinesAns: NTC
Largest category of electronicsAns: Computer
2nd largest category of electronicsAns: Communications
3rd largest category of electronicsAns: Control
Graphical transmission other than TVAns: videotext, teletex, facsimile
Difference of audio and sound for negative transmissionAns: 4.5 MHz
VSWR when terminated at ZoAns: 1
Wires that are in a fire proof ceilingAns: Poke through
Oldest form of modulationAns: AM
Simplest detectorAns: Diode detector
Most common cause of internal noise11
Comms Coaching•
Ans: Thermal agitation
Vary the DC voltage to vary the gainAns: Dual gate MOSFET
vary the collector current to vary the gainAns: BJT
Ceiling and visible area of VFO operating zoneAns: 3048-4827 mi
A feedback that is used to eliminate drift frequencyAns: frequency control oscillator
Rectangular hole on the floorAns: Slot
Increase gain Ans: decrease beamwidth
F connectorAns: RG58U
It is used as mixer (simplest)Ans: Resistor
Insertion loss of fiber opticsAns: 0.38 dB
A tap used in subscriber drop lineAns: high tap loss
Cladding of graded index multimode fiberAns: 0.05 nm
No claddingAns: Laser
Wide beam of missile guidance radarAns: Wide beam
SSB generation12
Comms Coaching•
Ans: filter method
It is used in filter methodAns: Quartz crystal
Suppressed carrier Ans: balanced modulator
Cheap filter methodAns: Ceramic filter
Highest Sound absorptionAns: Celotex
PBXAns: Star topology
Hierarchal topologyAns: SNA
Generator code of CDMAAns: PSN generator
Open ended slot antennaAns: Notch antenna
1544 kbps and 24 VB chAns: u-law
Decay of TV receiverAns: 5 ms
Most positive TVAns: 2nd anode
Common dispersion in fiber opticAns: Absorption and Rayleigh scattering
Popcorn noiseAns: Burst noise
13
Comms Coaching•
Theoretical distance of WiMaxAns: 50 km
Practical distance of WiMaxAns: 3 – 5 mi
Bit rate of BluetoothAns: 2.402 – 2.480 Mbps
CDPDAns: Cellular Digital Packet Data
Data rate of CDPDAns: 19.2 Mbps
Modulation technique of CDPDAns: GMSK
MPEG7Ans: Multimedia Content Description Interface
MPEG3Ans: Motion Pictures Experts Group 1, Audio Layer 3
Ribbon microphone is ___ microphoneAns: Pressure-gradient
Time for V scan lineAns: 1333 us
Under water pressure level sensorAns: Hydrophone
Used for error detectionAns: XMODEM
Discriminator on secondary detectorAns: Doppler radar
Father of internetAns: Vinton Cerf
14
Comms Coaching•
Weak RGBAns: Gray
Strongest signal colorAns: Yellow-green
I signal phaseAns: 57°
GPSAns: 1978
Angle of trust wind parabolic antennaAns: 56°
GPS inclination angleAns: 55°
H scan lineAns: 10.2 us
Fiber optic frequency near ___Ans: 800 THz
Demodulate PCM useAns: low pass filter
Diode detector usesAns: Rectification and filtering
Bandpass filterAns: IF amplifier
Turnstile antenna to feed 2 signals in 1 antennaAns: Circulator
Code 39Ans: Discrete Code
Types of Deiscriminator15
Comms Coaching•
Ans: PLL, Foster Seeley, Quadrature
Not primary superheterodyne receiverAns: RF amplifier
2 oscillatorAns: Black and White
Shadow maskAns: 300,000 holes
CRT capacitanceAns: 2000 pF
Noise margin of Optical fiberAns: 5 to 10 dB
Margin of safetyAns: Power margin
Bluetooth standardAns: IEEE 802.15
IEEE 802.15.4Ans: Zigbee
Data rate of WiMaxAns: 11-54 Mbps
Under the influence of inductance fieldAns: near field
Most dense at nightAns: F layer
Sound corresponds to color of lightAns: Pitch
All waves absorbed and reflectedAns: Labertian reflection
Reflects one color and rejects other16
Comms Coaching•
Ans: dichroic
MatrixAns: Combination circuit TV
FM luminance frequency for VCR recordingAns: 3.5 MHz
Control frequency of VCR1Ans: 30 Hz
Lowest layer for HF propagationAns: C layer
λ/2 150 MHZ at ___Ans: 1 meter
UHF connector to coaxAns: PL259
RS232C hasAns: 25 pins
3G slowAns: 384 kbps
3G fastAns: 144 kbps
3G stationaryAns: 2 Mbps
ILD disadvantageAns: temperature dependent
Reference noise temperatureAns: 290 K
10BASET cable, T meansAns: type of cable used
Convolution 17
Comms Coaching•
Ans: Trellis coding
MPEG 2 usesAns: Cosine transform
Disadvantage of fiber optic cableAns: Cable splicing and simplicity
Flutter echoAns: Successive echo
Telegraph consists of ___ characters plus word spaceAns: 7 ½
Above 10 Hz jitterAns: wander
Telephone wireAns: AWG 19
InterhostAns: Session layer
Measurement of height of ionosphereAns: Ionosonde
PEPAns: 1/3 to ¼
IF Sound carrier cableAns: 45.75 MHz
Connector TV at VCR lowest costAns: F-7 connector
EllipticalAns: Gregorian fed
Resonant antennaAns: Marconi
18
Comms Coaching•
When the main lobe of the array pattern is perpendicular to the array axis, the uniform linear array elements is known asAns: Broadside array
When the main lobe of the array pattern lies along the array axis, the uniform linear array elements is known asAns: end-fire array
What is non-continuous noise of irregular pulses or spikes of short duration with high amplitudes?Ans: Jitter
Strowger switchAns: 1897
Cause of attenuationAns: Walls of waveguide
480 pixel progressive formatAns: 640 x 480
HDTV has ___ more informationAns: 5
Video specification used for video compressionAns: MPEG4
Formula for S/N above 240 channelsAns: S = 4.47 d ( -15 + 10 log N ) N 20 Where: d = 200 kHz
Formula for S/N below 240 channelsAns: S = 4.47 d ( -1 + 4 log N ) N 20 Where: d = 35 kHz
pWpAns: pWp = 0.56 log-1 (90 – S/N)
( 10 )
Flat pWp19
Comms Coaching•
Ans: pWp = log-1 (90 – S/N) ( 10 )
Kr TE10
Ans: kr = 3.83
Kr TE11
Ans: kr = 1.84
Klystron factorAns: k = ____fo______
2(n+1)(1+2Vo)
ModeAns: mode = n +(3/4)
FormulaAns: 10 log (ng+ni)2
(ng-ni)
Relative permittivity of PVCAns: 3.3
Relative permittivity of polyethyleneAns: 2.27
NTSC Ans: 0.7 NL
PALAns: 0.8NL
Effective noise bandwidthAns: BWeff = (π/2)(BW3dB)
Parabolic antenna gain with respect to beamwidth Ans: G (dB) = 10 log (203/φ)2
BeamwidthAns: φ = 203
(√10)G(dB)/10
20
Comms Coaching•
Five wire lineAns: Zo = 173 log __D__
√ξr 0.933 d
Balanced line between grounded parallel planes Ans: Zo = 173 log _4h tanh (πD/2h)_
√ξr πd
Number of modes fiber opticAns: M = 0.5 (πD NA/λ)2
Q of SSBAns: Q = fo (log -1 dB/20) 1/2
4Δfi
Reliability based on propagationAns: Undp = abfGHz
1.5 dmi3 (1.25 x 10-6)10-FM/10
R = (1- Undp) x 100%
Reliability based on equipment failuresAns: U = Outage time in hours/year
8760 hours
Earth’s curvatureAns: EC = d1d2
1.5k
Absorption coefficientAns: α = δa/S
δa = (55.3 V/v)(1/t1 – 1/t2)
Effective noise BW parallel tuned circuitAns: BWeff = 1/(4RpC)
Reject a single color and allow other colorsAns: Dichroic
Hertz antenna used above Ans: 2MHz
21
Comms Coaching•
Elliptical reflectorAns: Gregorian Fed
Used in LOS transmissionAns: VHF
Used in submarine applicationsAns: ELF
Used in marine and aeronautical communicationsAns: L-band
Lowest attenuation fiber optic lengthAns: 1000 ft
Longest wavelengthAns: Orange
Results from the combination of weak blue, red and greenAns: Gray
Electron gun goes straight to the picture tubeAns: Green
Protocol which uses checksum as error detection schemeAns: XMODEM
Video specification used for video compressionAns: MPEG4
Used in European Cordless TelephoneAns: GFSK
Microwave telephone via satelliteAns: Arthur Clarke
Foundation of acoustic theory in buildingsAns: Wallace Sabine
22
Comms Coaching•
Father of InternetAns: Vinton Cerf
Chrome type cassette tapeAns: Type 2
Protection from snow and windAns: Radome
Daytime ; reflect low frequencies, absorb medium frequenciesAns: Layer
Most denseAns: F2 layer
transequatorial propagation Ans: best in afternoon and early evening
Aspect ratio of HDTVAns: 16:9
Without bottle necksAns: Mesh
480 pixel format Ans: 640 x 480 pixel progressive
Lifetime of LEDAns: 200,000 hrs
Number of holes in shadow maskAns: 300,000
Lead oxide camera tube Ans: Plumbicon
Acts as an antenna at high frequenciesAns: Transmission line
Reference in dbaAns: -85 dBm
23
Comms Coaching•
Reference temp in noise analysisAns: 290 K
Audible frequency rangeAns: 16 Hz – 16 kHz
RG62 to avoid reflection use Ans: 93 Ω
Used in thick EthernetAns: RG11
RS232C Ans: has 25 pins / 20 kbps
1 supergroupAns: 75 groups
Heating voltage of TV picture tubeAns: 6.3 V
Wi-FiAns: 11-54 Mbps
WiMax theoretical rangeAns: 50 km
WiMax practical rangeAns: 3 to 5 miles
1 jumbogroupAns: 3600 VC
BluetoothAns: IEEE 802.15
WiMaxAns: IEEE 802.16
Zigbee24
Comms Coaching•
Ans: IEEE 802.15.4
Angular separation between half-power pointsAns: Beamwidth
Prevent FM from enteringAns: Diplexer
Not temperature dependentAns: ILD
Color subcarrierAns: 3.58 MHz
Highest absorbent coefficient materialAns: 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 wallsAns: Anechoic
Cause of attenuationAns: Walls of waveguide
Bending of light from high density to low densityAns: Refraction
Adjustment used by means of loudspeaker feedback systemAns: Ambiophony
25
Comms Coaching•
Uses convolutional coding Ans: Trellis Coding
Inverter CMOS Ans: has two transistors
SSB Ans: AM
Uses CSMA/CD ; 10 MbpsAns: Ethernet
Structure which supports cablesAns: Cable Tray
GPRS uplink rateAns: 14 kbps
Tunes to a radio frequencyAns: Local oscillator
Two PBXAns: Tie Trunk
Hierarchical topologyAns: SNA
Types of demodulator : Ans: PLL, Quadrature and Foster – Selley
Violet ray Ans: 4000 Angstrom = 0.4 micron
PopcornAns: Burst noise
Used to view the envelop of a modulated signalAns: Oscilloscope
Power output of sideband envelopeAns: Peak Envelop power
26
Comms Coaching•
Disadvantage in using FOCAns: Splicing
Causes distortion on the demodulated signal (delta modulation)Ans: Slope overload
Spread spectrumAns: DSSS
Mostly used in satellite communicationsAns: TDMA
High internal resistanceAns: Nickel Iron
Protection against snow and wind loadingAns: 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-phaseAns: QAM
Fgure of merit with FSKAns: h factor
OSI layer – buildings
27
Comms Coaching•
Ans: Novell Network
FluctuationsAns: Fading
Most common light generatorAns: ILD
Lifetime of LCDAns: 200,000 years
BFO of SSBAns: Carrier oscillator
Freq hopping, assign diff carrier freqAns: CDMA
Antenna complete in itself and self-oscillatingAns: Hertz Antenna
Unique binary code for CDMA satelliteAns: Chip code
Output of magnetic microphoneAns: 1 mV
350-440 HzAns: call-waiting tone
Connect telephoneAns: Induction coil
Conduit, reduce abreactionAns: Bashing
Most reliable for error detectionAns: CRC
Use 2 mixers, filter & phase-shiftAns: Balanced modulator
28
Comms Coaching•
1% left in the TVAns: Screen persistence
Unconscious level heard by human earAns: 6-10 dB
Microwave range of freqAns: Window
Marginal safety for microwaveAns: 5 – 10 dB
Luminance FM for VCRAns: 2.5 MHz
Non-directional horizontally polarizedAns: VHF & UHF
Stereo pilot carrier Ans: 19 kHz
Dipole resistanceAns: 73 ohms
RG-65 Ans: 93 Ω
Complex pressure amplitude over complex amplitude volumeAns: Acoustic impedance
Optical densityAns: Radiant flux
HDTV Ans: 16:9
Calls not satisfiedAns: Erlang C
PBXAns: Star topology
29
Comms Coaching•
Blanking pulse of negativeAns: 75%
Beginning & end of the char codeAns: Character Synchronization
Improve AM broadcast timerAns: Counterpoise
Visible signalAns: Infrared
Variations in signal strength by atmospheric conditionsAns: Fading
For abrasionAns: Abrasion
Known for power amplificationAns: Class A
Injection laser diode Ans: APD
1st radio receiverAns: Crystal
Communication for vehicle, groundAns: Marconi
Visible wavelengthAns: 0.4 to 0.8 micron
Radiation directionAns: End fire array
IMPATTAns: 30 GHz
Logic network in form of an array30
Comms Coaching•
Ans: Matrix
Across resistorAns: Shot noise
Information capacity Ans: Shannon Hartley theorem
Divide digital dataAns: Converter
Sum of minterm & product of maxtermAns: Canonical
Handset local loopAns: Induction coil
Figure of merit in lightAns: Numerical aperture
All constantAns: Diatonic
Purity of colorAns: Q & I amplitude
Maximum brightnessAns: 50% Red 59% Green and 11% Blue
Handshaking principleAns: Delta modulation
Handshaking principleAns: Synchronous
Error correction at high frequencyAns: ARQ
UnicodeAns: 16 bit long
High frequency AM31
Comms Coaching•
Ans: PIN diode
ModemAns: PSK
Absorption of impedance TubeAns: α = 4A1A2
(A1+A2)2
Impedance acousticsAns: Newton seconds per cubic meter
WiMax data rateAns: 500 kbps – 8 Mbps
FormulaAns: ft = fo + kfoΔT
Blind velocityAns: Vb = PRF(nλ/2)
Spacing of transmission lineAns: S = λL/360
Transfer of one adjacent walls to anotherAns: Flanking transmission
Range that accepts signal interferenceAns: Blocking range
Sound deduction indexAns: Transmission loss
Internet cable 6 MHzAns: 27 Mbps
Not terrestrial TVAns: 8-V.58
Lowest attenuation UHFAns: N-type
32
Comms Coaching•
HFAns: affected by the solar cycle
Pag tinanong linear bit PCM codeAns: n-1
PhotonAns: E = hf/c h=6.634 x 10-34
SSBAns: HF
High ZAns: Crystal
U600 bandwidthAns: 2520 MHz
Standard VBAns: 300 – 3400 Hz
Voice gradeAns: 0 – 4 kHz
170 Ω/km Customer loopAns: AWG22
Determine attenuation to troposcatterAns: Scatter angle
CompressionAns: SSB = 20 log cot(φ/2)
KlystronAns: n +3/4
TimeAns: TD = 1.016 √ξr (length) ns/ft
0 = 360 TD
T33
Comms Coaching•
One tenth of the wavelengthAns: Elementary doublet
FOC data rate Ans: data rate = 1/5Dd
Minimum heightAns: λ/4
Theoretical heightAns: λ/2 vertical antenna
LORAN C/D accuracyAns: 460 m
COR/DME ground navigationAns: 108 – 118 MHz
Repeater fiber optic cableAns: 10 – 30 km
dBaAns: 1 uV/m
Bridge Ans: Physical and data link
Transmission and reception of informationAns: Session
Transmission of bitsAns: Physical
Start bitAns: 0
Stop bitAns: 1
Noise temperature34
Comms Coaching•
Ans: 17°C
AC cableAns: All of the above
Not specification of 3GAns: IMT2000
BW efficiencyAns: Information density
ResolutionAns: Resolution = Vmax/DR
Quantization errorAns: Q = (1/2)Res
Isolation CATVAns: 28 dB
Output terminal match CATVAns: 16 dB
Disadvantage of plastic over glassAns: High attenuation
Mnimum illumination for readingAns: 8000 Ix
Impedance at open end of half wave antennaAns: 2500 ohms
Max data rate of fiber optic systemAns: 10 Gbps
Data rate of TDMAAns: 8 kbps
WiMaxAns: 500 kbps to 8 Mbps
35
Comms Coaching•
H21 broadband ISDNAns: 32.786 Mbps
Data rate of terrestrial digital TVAns: 32.28 Mbps
V.34Ans: 33.6 kbps
GPRSAns: 172.2 kbps
BluetoothAns: 72 kbps
V.22Ans: 1200 kbps
V.90Ans: 56 kbps
V.32Ans: 9.6 kbps
Speed of IS-95 CDMAAns: 1.23 Mbps
WiFi / wireless internet service providerAns: 11 Mbps
WiFi specAns: IEEE 802.11b
Spacing between M88 loading coilsAns: 9000 ft
Area above the vertical antennaAns: curve of silence
under the influence of the induction fieldAns: near field
36
Comms Coaching•
FM luminance frequency for VCR recordingAns: 3.5 MHz
Measure of comparison of sound intensity with another Ans: decibel
Used in optical system and satellite telemetry linksAns: biphase codes
Divide into 4 by ITUAns: Facsimile groups
Code transparency with frequencyAns: bit oriented protocol
ERP of class 2 cellular mobileAns: 1.6 W
Max power for class I analog mobileAns: 600 mV
Appears at nightAns: F2 layer
High frequency daytime propagationAns: E layer
MF range wavelengthAns: Hectometric waves
Protocol for packet switching networksAns: X.75
Electronic serial numberAns: 32 bits
Most luminanceAns: Yellow
Used by Marconi antenna37
Comms Coaching•
Ans: below 2 MHz
Mogul-Dellinger fadeout Ans: sudden ionospheric disturbance frequency
Most commonly used characters are represented in fewer bitsAns: Huffman encoding
On time of FETsAns: Acquisition time
Term for byte in ATMAns: Octet
Used in 10/100 Mbps EthernetAns: ISTP cable
Not used in TVAns: 108 MHz – 114 MHz
Does not use error checkingAns: Physical layer
Demodulates audio signal in TVAns: Discriminator
Together with mixerAns: local oscillator
Not used in mobile tel.Ans: balanced detector
Guardband of C-band satellite comm.Ans: 4 MHz
Minimum quality circuit available in PTNAns: basic voice grade
Multichannel network Ans: broadband
38
Comms Coaching•
Standard test toneAns: 1000 Hz
Average human absorptionAns: 4.7 units or sabines
Max. critical angleAns: Acceptance angle
Software used in preparing packetsAns: internet protocol
No modulationAns: Rest frequency
CMTS(AMPS)Ans: Less than 2%
Speed of longitudinal waves Ans: is proportional to the compressibility of the medium
EIRP Class II Cellular Ans: 1.6 watts
Pulse dialingAns: 10 pulses/sec or 600 pulses/minutes
Single-sideband full-carrierAns: H3E
Retain local number to access (migration)Ans: Local number portability
‘raceway’Ans: Header
Fastest multimedia peripheralsAns: Firewire
Output Class I mobile output minimumAns: 600 mV
39
Comms Coaching•
Smallest unit data for networkAns: Packet
UTC Ans: UTA
Mod used for IS-95Ans: QPSK (DSSS)
Propagation delay for TDM periodAns: 577 us
Difference freq for forward and backward transmissionAns: 45 MHz
Gain at the direction of the major lobeAns: Directivity Gain
Code transparencyAns: Bit-oriented protocol
AM broadcast antenna heightAns: λ/2 vertical antenna
Synchronization 1 VAns: Scanning line
Can be eliminated using helical antennaAns: Faraday rotation
Companding Ans: protect small signals from quantizing distortion
Current Maximum for ¼ wavelength Marconi AntennaAns: at the base
Synchronous data transferAns: CMT
Electrical signals converted for microphoneAns: 25 – 8000 Hz
40
Comms Coaching•
Reference sound levelAns: 0 dBm
Bessel 1.0 modulation indexAns: 3 pairs of sidebands
Common coaxial characteristic impedanceAns: 50Ω and 75Ω
Dead space Ans: due to shading of hills and trees
Formulas: θ=
360 ° T DT
(phase shift)
T=1f
TD=1.016√∈d ns/ft (d in ft)
Illuminated reflector
θ=142 °√G
(beamwidth), (G = in gain ratio)
f=f o+k f o∆T
8 kHz1MHz
→Hartley
1ppm → 1Hz1MHz →crystal
BER = (bit error rate)
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