Week 12 Chapter 6 Part 1 - Pages 6-1 to 6-32

Question 1

Overall bandwidth of optical fiber is a derivative of two components: modal dispersion and chromatic dispersion. In multimode optical fiber, _____ predominates.

a. Modal dispersion
b. Chromatic dispersion

Answer 1

a. Modal dispersion

p 6-18

In multimode, modal dispersion predominates, and chromatic dispersion is negligible; in singlemode, it is the opposite.

Question 2

Optical fiber cabling applications are length restricted on the style of cabling. For 1 Gb transmission standards, what is the typical distance supported by OM1 cable?

a. 220 m (722 ft)
b. 300 m (984 ft)
c. 550 m (1800 ft)
d. 1000 m (3281 ft)

Answer 2

a. 220 m (722 ft)

p 6-18 see Table 6.6

Question 3

A number of measurable characteristics control the transmission performance of a balanced twisted-pair cable. Which one of the following is not considered to be a primary parameter?

a. Capacitance
b. Conductance
c. Resistance
d. Return loss

Answer 3

d. Return loss

p 6-10

Primary parameters, which depend on the physical nature of the conductor—materials (conductivity and permittivity) and dimensions (wire gauge [copper diameter], insulation diameter and thickness, conductor spacing)—are:
–Resistance (R).
–Conductance (G).
–Inductance (L).
–Capacitance (C)

Question 4

For screened (shielded) balanced twisted-pair cable the screening material type, thickness and relative coverage determines the effectiveness of the screen. ___ effectively blocks lower frequency (below 30 MHz) electromagnetic fields.

a. Foil
b. Copper braid

Answer 4

b. Copper braid

p 6-11

The screen’s characteristics are such that the:
• Foil typically blocks higher frequency (30 MHz and higher) electromagnetic fields.
• Copper braid effectively blocks lower frequency (below 30 MHz) electromagnetic fields.

Question 5

The overfilled launch (OFL) bandwidth for OM3 multimode optical fiber cable at a wavelength of 850 nm is:

a. 1500 MHz-km
b. 2000 MHz-km
c. 3500 MHz-km
d. 4700 MHz-km

Answer 5

a. 1500 MHz-km

p 6-15 see Table 6.5 - Optical fiber cable transmission performance parameters.

Note, all multimode at wavelength of 1300 nm = 500 MHz-km

Study all parameters in the table and understand the difference between overfilled launch (OFL) and effective modal bandwidth (EMB). They’re on the test.

Question 6

Series-11U coaxial cable has a ___ center conductor.

a. Stranded
b. Solid

Answer 6

a. Stranded

p 6-25

Series-11U has a(n):
• Characteristic impedance of 75 ohms.
• Coated foil shield over the dielectric to shield against high frequencies.
• Braided shield over the coated foil to shield against low frequencies.
• 18 AWG stranded center conductor.
• F- or N-style connector.

Question 7

The most common tight-buffer diameter is:

a. 900 μm
b. 600 μm
c. 250 μm
d. 125 μm

Answer 7

a. 900 μm

p 6-21

The most common tight-buffer diameter is 900 μm, although other diameters are available.

Has the most common loose-tube optical fiber diameter of 250 μm, although other diameters are available.

Question 8

___ indicates the conductors insulation’s ability to transmit an electric field.

a. Conductivity
b. Permittivity

Answer 8

b. Permittivity

p 6-9

Permittivity indicates the insulation’s ability to transmit (or permit) an electric field.

Question 9

Multimode optical fiber supports a common wavelength of 850 nm when a(n) _____ is used for a light source.

a. VCSEL
b. LED

Answer 9

a. VCSEL

p 6-16

Supports common wavelengths of 850 nm VCSEL and 1300 nm LED.

Question 10

Insulating materials can affect the physical size of a completed balanced twisted-pair cable and determine all four of the primary electrical characteristics.

a. True
b. False

Answer 10

b. False

p 6-9

Insulating materials can affect the physical size of the completed cable and determine TWO of the four primary electrical characteristics of the balanced twisted-pair:
• Mutual capacitance
• Permittivity

Question 11

The wavelengths associated with OM5 multimode optical fiber cables are:

a. 880/910 nm and 1300/1550 nm
b. 850/880 nm and 910/940 nm
c. 850 nm and 1310 nm
d. 850 nm and 1300 nm

Answer 11

b. 850/880 nm and 910/940 nm

p 6-15 Table 6.5

Question 12

All balanced twisted-pair cables consist of solid or stranded conductors as well as the following components:

a. Dielectric insulation, shielding, outer sheath, pair separators
b. Outer jacket, thermoplastic insulation, strength member, ripcord
c. Thermoplastic insulation, outer jacket or sheath

Answer 12

c. Thermoplastic insulation, outer jacket or sheath

p 6-8

All balanced twisted-pair cables consist of the following components:
• Solid or stranded conductors
• Thermoplastic insulation
• Outer jacket or sheath