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14th Reading > Chp 1 > Flashcards

Chp 1 Flashcards

1
Q

Solid conductor Advantage

A

Price
Conductivity at high frequency
Resistance
Less complex termination systems

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2
Q

Stranded conductor advantage

A

Flexibility

Less prone to damage (during termination, and over lifetime of flexing)

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3
Q

Most common conductors in ICT

A

Copper
Copper clad steel
Copper Alloy
Aluminum

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4
Q

Conductor used for electrical utility distribution, why

A 
Aluminum
Lightest conductor with 60% conductivity. 
Other characteristics; 
Good: ductility, corrosive resistance 
Poor: oxidative resistance
Weight: approx 1/3 of copper
Tensile strength: < 1/3 of copper
Solderability: requires special techniques
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5
Q

Conductor for self supporting cable

A

Type & Application:

Copper clad steel, for aerial drops

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6
Q

Strongest conductor type

A

Type & application:
High strength alloys
used in aerospace and computer to meet specific characteristic requirements

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7
Q

Composite conductors

A

Type & Application:
Pourable mixture to cure in cast/casing for embedded conductor applications.
ICT use: DONT. Trash it, and use other conductors if provided with equipment

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8
Q

Insulators used for plenum

A

PVC

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9
Q

Insulatior properties

A

Dielectric strength
IR (insulator resistance)
Dielectric constant
Dissipation factor

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10
Q

Desired dissipation factor

A

Low.
This factor increases with signal frequency, and esp. concerning in MHz range (loss due to thermal exchange from “microwaves”)

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11
Q

Desired Dielectric strength

A

high

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12
Q

Desired dielectric constant

A

low, generally

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13
Q

Desired IR

A

High

IR is determined by cable length (inverse relationship)

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14
Q

Pair-to-pair capacitance unbalance is

A

a measure of the electric field coupling between two pairs if a differential voltage is applied on one pair and a differential noise voltage is measured on another pair in close proximity.

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15
Q

Mutual inductance is

A

a measure of the magnetic field coupling between two pairs if a differential current is applied on one pair and a differential noise current is measured on another pair in close proximity.

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16
Q

Cross-talk measured by

A

Mutual inductance and capacitance unbalance

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17
Q

Tight twisting length

A

<12.7mm (.5”)

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18
Q

Tight twist transmission effect

A

Preserves twists better, and therefore transmits signal more effectively

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19
Q

Cable types using tight twists

A

CAT5e, 6, 6A & higher

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20
Q

Tight twist physical effect

A

Cable structure maintains better

21
Q

Environmental design considerations

A

Max temperature

EMI sources

22
Q

Cable characteristics affected by temperature

A

What, trait
Conductor, resistance
Insulator, Dissipation factor
Insulator, Dielectric constant

23
Q

High temperatures likely to be found in

A

ceilings/plemuns
exterior walls
mechanical rooms
& cables using high levels of PoE

24
Q

Why temperature matters

A

Directly proportional to attenuation

25
Q

Attenuation is determined by mdeium’s

A

Dielectric constant
Dissipation factor
Conductor resistance

26
Q

Design systems using the ____ temperature

A

potential highest

27
Q

Cabling standard reference for design

A

All twisted-pair cables are referenced in the cabling standards at 20 °C +/- 3 °C (68 °F +/- 5.4 °F). For adjustment purposes, the attenuation increase is 0.2 percent per degree Celsius for temperatures above 20 °C (68 °F) for screened cables, 0.4 percent per degree Celsius for all frequencies and for all temperatures up to 40 °C (104 °F), and 0.6 percent per degree Celsius for all frequencies and for all temperatures from 40 °C to 60 °C (104 °F to 140 °F) for all unscreened cables.

28
Q

Shielding cable

A

helps to maintain signal quality

29
Q

Often used with shields for the purpose of____

A

What, fill in blank

Drain wires, providing a conveinent means to ground shield & maintain continuity across perforations/braids/etc

30
Q

Phase is

A

What, units
Reference of time in respect to the signals period
Period is 360 degrees, i.e. 1/4 period = 90 degrees

31
Q

Sinusoidal signal described mathematically

A 
formula
v(t)=A*sin(2 pi f t + ø)
A=amplitude
f=freq
t=time
ø=phase
32
Q

Signal theory developed by

A

who

joseph fourier

33
Q

Fourier’s Analog Signal Description

A

Any analog signal can be described by multiple sinusoidal signals. Each signal would be considered a component of the signal it represents.
Collectively, these signals are referred to as the signals SPECTRUM.
The difference across the frequencies which these signals have is the bandwidth of the signal.

34
Q

Used to express strength of signals

A

dB, dBm (dB referencing 1mW),dBW (dB referencing 1W)

35
Q

dB is

A

a ratio of power output to power input.

Often a standard unit is used to compare signals rather than using input

36
Q

Echo

A

When a signal encounters a discontinuity in the impedance of the medium carrying the signal, some of the signal power is relected back to the transmitter.

37
Q

Complex signals with many components use ___ instead of _____

A

Time, phase.

because phase can be described as delay in time

38
Q

The application of inductors, called _________, placed at intervals along a cable improves speech transmission quality.

A

loading coils

39
Q

Loading coils

A
  • Compensate for the capacitance of a cable pair.

* Reduce the capacitive current loading in the range of audio frequencies.

40
Q

In telephony, Data speed transmission depends on

A

signal frequency (& medium characteristics: capacitive balance & mutual impedance)

41
Q

Higher frequencies travel _____ than low frequencies

A

faster

42
Q

Loading coils solve the speech quality issue but create a _______ issue

A

transmission delay

43
Q

Distance between loading coils determines the _____ frequency and have a _____ relationship

A

cut off

inverse

44
Q

Most common distances between loading coils

A

1.37km (for D loading) & 1.83km (for H loading)

45
Q

Issues in analog telephony

A

Issue, cause, solution, side effect

Distortion, change of mediums/impedance & distance, loading coils, signal delay

Echo, impedance change weakens signal cuz some bounces back, loading coils strengthen signal, signal delays

46
Q

IP Telephony

A

Uses data cabling
Recommended dedicated jack so computer & phone dont compete
Life safety telecom applications should use POE & UPS

47
Q

***Add cards with standards applicable to CAT3, CAT5, CAT6 from Table 1.17

A
48
Q

*** ADD Table 1.18 cable lengths/transmission rates & applications

A
49
Q

Although the cabling transmission parameters are complex, the inal result is that a transmission circuit should be cost-efective, meet applicable standards, and have:

A

• A uniform characteristic impedance that is matched to the equipment
.• Low insertion loss/attenuation.
• High SNR and available bandwidth.
• Velocity of propagation that is relatively constant with frequency
.• High NEXT and FEXT loss between pairs
.• High NEXT and FEXT loss between pairs in adjacent cables and connectors
.• High noise immunity.

14th Reading (13 decks)

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