Telephone Circuit

Question 1

is the only facility required by all voice-band circuits, as it is the means by which the subscriber locations are connected to the local telephone company

Answer 1

Local Loop

Question 2

the sole purpose of the local loop is to provide subscriber access to the ___

Answer 2

PTN - Public Telephone Network

Question 3

7 Main Components that make up a traditional local loop

Answer 3

1. Feeder Cable
2. Serving Area Interface
3. Distribution Cable
4. Subscriber or Standard Network Interface
5. Drop Wire
6. Aerial
7. Drop-wire cross-connect point

Question 4

The largest cable used in a local loop, usually 3600 pair of copper wire placed underground or in a conduit.

Answer 4

Feeder cable

Question 5

A cross-connect point used to distribute the larger feeder cable into smaller distribution cables.

Answer 5

Serving-area interface

Question 6

A smaller version of a feeder cable containing less wire pairs

Answer 6

Distribution cable

Question 7

The portion of the local loop that is strung in between poles.

Answer 7

Aerial

Question 8

A device that serves as the demarcation point between the local telephone company responsibility and the subscriber responsibility for telephone service

Answer 8

Standard network interface

Question 9

Final length of cable pair that terminates at the SNI

Answer 9

Drop wire

Question 10

The location where individual cable pairs within a distribution cable are separated and extended to the subscriber’s location on a drop wire

Answer 10

Drop wire cross-connect points

Question 11

Studies of attenuation on cable pairs have shown that substantial reduction in attenuation is achieved by increasing the inductance value of the cable

Answer 11

Loading Coils

Question 12

decrease the attenuation, increase line impedance, and improve transmission levels for circuits longer than 18000 feet

Answer 12

Loading Coils

Question 13

are unused sections of a cable that are connected in shunt to a working cable pair, such as a local loop

Answer 13

Bridge taps

Question 14

Were used for party lines to connect more than one subscriber to the same local loop

Answer 14

Bridge taps

Question 15

is comprised of 2 or more facilities, interconnected in tandem to provide a transmission path between a source and a destination

Answer 15

Telephone Circuit

Question 16

Information or __

Answer 16

Message

Question 17

Circuit used in telephone circuit

Answer 17

Message Channel

Question 18

In telephone terminology, ___ denoted speech information

Answer 18

Message

Question 19

Are unused frequency bands located between information signals

Answer 19

Guard Bands

Question 20

Local loop is the primary cause of __ and ___

Answer 20

Attenuation and Phase Distortion

Question 21

Transmission characteristics of a local subscriber loop: (4)

Answer 21

• wire diameter
• conductor spacing
• dielectric constant
• conductivity of the wire

Question 22

The electrical characteristics of a cable (resistance, inductance, capacitance) are uniformly distributed along its length, referred to as

Answer 22

Distributed Parameters

Question 23

Noise signals with equal interferring effects are assigned equal magnitude. To accomplish this effect, AT&T developed a weighting network called

Answer 23

C-message weighting

Question 24

Assumes a perfect receiver, therefore its weighting curve corresponds to the frequency response of the human ear only

Answer 24

Psophometric Noise Weighting

Question 25

dBm referenced to 0 TLP

Answer 25

dBm0

Question 26

dB level of noise with respect to reference noise (-90 dBm)

Answer 26

dBrn

Question 27

same to dBrn except dB value of noise is with respect to reference noise with C-message weighting

Answer 27

dBrnC0

Question 28

noise readings taken with a filter that has a flat frequency response from 30 Hz to 3 kHz

Answer 28

dBrn 3kHz flat

Question 29

dBrn 3 kHz flat readings are typically ____ db higher than dBrnc reading for equal noise power levels

Answer 29

1.5 dB

Question 30

amount of noise in dBrnc corrected to 0 TLP

Answer 30

dBrnc0

Question 31

Apply to dedicated private-line data circuits that utilize the private sector of the PTN

Answer 31

Transmission Parameters

Question 32

Circuits with BW comparable to those of standard voice-grade telephone channels that do not utilize the PSTN

Answer 32

Private-line Data Circuits

Question 33

Difference in circuit gain experienced at a particular frequency with respect to the circuit gain of a reference frequency

Answer 33

Attenuation Distortion

Question 34

Process used to improve the basic telephone channel

Answer 34

line conditioning

Question 35

is a relatively low-capacity switching machine where the subscriber are generally limited to stations within the same building or building complex

Answer 35

PBX or private branch exchange

Question 36

pertains line impairments for w/c compensation can be made with filters and equalizers

Answer 36

C-type line conditioning

Question 37

Neither reduces the noise on a circuit nor improves the SNR; Simply sets the minimum requirements for SNR and non-linear distortion

Answer 37

D-type line conditioning

Question 38

originally coined to indicate the presence of unwanted speech sounds in a telephone receiver caused by conversations on another telephone circuit

Answer 38

Crosstalk

Question 39

is a direct result of nonlinear amplification in analog communications system

Answer 39

Nonlinear Crosstalk

Question 40

interference caused by inadequate control of the transfer characteristics or transmittance of networks

Answer 40

Transmittance Crosstalk

Question 41

eletromagnetic coupling between 2 or more physically isolated transmission media

Answer 41

Coupling Crosstalk

Question 42

2 types of coupling crosstalk

Answer 42

• near-end cosstalk (NEXT)

- far-end crosstalk (FEXT)

Question 43

is a decrease in circuit gain of more than 12 dB lasting longer than 4ms

Answer 43

dropout