Ch. 1 * (Principles of Transmission) Flashcards
Alloying
Adverse effect
Advantages of stranded conductors
Except better transmission
Another name for insulation
Dielectric
North America standard
American Wire Gauge
Teflon
Dupont
Dielectric strength
Measures maximum voltage an insulation can withstand without breakdown
Reason for twisting pairs
Minimize Crosstalk
Mutual inductance
Magnetic field
Direction of twists
Counter clockwise
Where are high temperatures found?
Exterior building walls, ceiling spaces, mechanical rooms
Types of shields
Fiber does not belong
Braid
Good
Foil
Excellent
Shield effectiveness
Less than 20 dB = poor
More than 60 dB = excellent
Braid/Magnetic Field rating
Poor
Drain wires
Applied longitudinally
Analog signal
Sign wave
Range of human hearing
20-20,000 Hz
Frequency of telephone circuits
300-3,400 Hz
Wave
Sinusoidal
Sinusoidal theory
Joseph Fourier
Most common electrical conductors…
Fiber does not belong
Phase
Time
One watt of power on your input and one milliwatt of power on your output - what is the total amount of power lost in dB?
30
Telecommunications transmission system consists of three basic components:
Source
Medium
Receiver
Speed of light
186,000
Speed of cable
.56c - .74c
Round-trip delay for satellites
.25
Power source options for VoIP
Except “bridge”
Digital signals
Discrete steps
One cycle
360 degrees
Sampling theory
Harry Nyquist
Companding types
Mu-Law
A-Law
Companding standard for U.S.
Mu-Law
PCM
Pulse Code Modulation
PCM
256
OC1
ATM (STS-1)
Encoding rate of STS–1
51.8 Mbps
OC-3
ATM (STS-3)
Encoding rate of STS–3
155 Mbps
Transmission circuit classifications
Simplex
Half duplex
Full duplex
Except…
Baseband analog signal types
Composite
Component
Component format
RGB
Resistive model
Teeth
Inductive model
Rings
10 milliwatt signal on input lead and 10 microwatt of noise in a 1,000’ run:
SNR = 20dB
10BASE-T
10BASE-T4
4 Pairs
Three parts comprising a simple telecommunications system:
Transmitter
Receiver
Medium
Multimode wavelength
850
1300
Single mode wavelength
1310
1550
VCSEL
Vertical cavity surface emitting laser
Factors for determining fiber type
Distance
Bandwidth
Active equipment
OM1
62.5/125
OM2
50/125
OM3
50/125 (laser)
OS1
Singlemode
OS2
Singlemode (low water-peak)
Frequency of category 3
16 MHz
Frequency of category 5e
100 MHz
Fiber dispersion
Picoseconds
Classifications of fiber
Multimode
Singlemode
Supported distance of 1 Gbps over multimode
1,804’
Singlemode attenuation
.5dB - OSP
1dB - Inside Plant
Channel continuation distance calculation:
of strands X .75 + .3dB
Power penalty
LED = 2dB Laser = 3dB
Repair margin
Two splices
Connection loss
.75dB
Four steps for converting analog signals to digital:
Filtering
Sampling
Quantizing
Companding
OC-1
28 T1s
OC-3
(3) OC-1s
OC-12
(4) OC-3s
WDM
Lenses
DS1
T1
DS1C
Bonded T1
OC-1
DS3
Splice loss
.3dB
Common electrical conductors
Copper
Copper covered steel
High-strength copper alloys
Aluminum, silver and gold
Used for reference value
Annealed copper
Sets the standard for comparing conductivity of other metals
Copper
Corrosion resistance of high-strength alloy
Poor
Oxidation resistance of aluminum
Poor
Advantages of solid conductors
Less expensive
Less complex terminations
Better transmission performance
Lower dielectric =
Better transmission performance
Common insulation types
PVC - polyvinylchloride
PE - polyethylene
Insulation used for low smoke (better performance)
FEP - flourinated ethylene propylene (Teflon)
ECTFE - ethylene clorotriflouroethylene (halar)
Neoflon
Daikin
Halar
Solvay Solexis
Lowest dielectric insulation
FEP
Dielectric constant of air
1.0
Dielectric constant (def.)
Ratio of capacitance between insulated conductor and uninsulated conductor in air
Insulation resistance (IR)
The longer the cable the less the IR (insulation resistance)
Capacitance unbalance
Electric field coupling
Temperature for balance twisted-pair cables
Attenuation increases above 68°
Shields reduce ___
Radiated signals
EMI
Effects of electrical hazards
Types of shields
Braided Spiral wrapped Foils Hybrids Metal tubes
Best shield
Conduit (metal tube)
Non-grounded shield
Effectiveness is reduced
3 dB =
Halving or doubling the power ratio
Max transmission occurs when ___
Transmitting/receiving device have:
- same load
- same impedance
Loading coils
Improves speech quality
D loading
4495’
H loading
6004’
Codecs
Conversion of speech
Baud
Modem
BRI
160 Kbps
STS
Synchronous Transport Signal
Bipolar alternate mark inversion
AMI (graphic looks like a heartbeat)
Biphase Manchester
Graph looks like Manhattan building’s skyline
Synchronous
Single master clock
HDSL
High bit rate DSL (2 pair)
SDSL
Symmetrical DSL (1 pair)
Electrical conductor (def.)
Any material that can carry an electric charge
RF Carrier
TV channel
Traditional video transport medium
Fiber
Coax
NVP (nominal velocity propagation)
Stated as a percentage of the speed of light
Delay skew
45 nanoseconds
Return loss
Power of reflected signal
Impedance mismatch
Signal reflections (echo)
Attenuation to Crosstalk Ratio (ACR)
Minimum NEXT - Maximum Attenuation
Impedance matching device
Balun
EIA 232-F
150’
DS1 distance
4920’
Frequency of category 6
250 MHz
Frequency of category 6a
500 MHz
PSEC
Picoseconds
Visible light
400-700 microns
Attenuation of light
Visible – higher
Infrared – lower
Wavelength for suitable communications
Window
Mechanical splice
Temporary
Fusion splice
Permanent
Inventor of ethernet
Metcalf
Lenses
Refract light
Multimode loss
850 = 3.5 dB 1300 = 1.5 dB
Multimode characteristics
Chromatic and modal dispersion
TDM
Combines multiple streams/signals
Methods of encoding
Manchester
AMI
Private line
600 Ohms
Central office
900 Ohms
Phenomenon
Echo
Solid wall metal tube =
Conduit
Pair to pair capacitance unbalance
Electrical field
Bandwidth can be expressed as ___
PSACR > 0
Average splice loss for singlemode mechanical splice
.10 dB
Fiber transmitter power measured in ___ or ___
dBm or mW
Fiber transmission change in intensity
Modulation frequency
VDSL
ATM
Propagation of balance twisted-pair depends primarily on ___
Dielectric materials surrounding conductors
Transmission systems designed for analog are ___ w/ digital
Not efficient
Encoding
Manchester
Differential Manchester
Bipolar alternate mark inversion (AMI)
Except “pulse coding”
Range of wavelengths
Spectral width
Numerical aperture value of OM1
0.275
Multimode and singlemode connector parts are ___
Compatible
Minimum system loss for fiber
Excess system gain over receiver dynamic range