CHAPTER 17
THE TELEPHONE CIRCUIT
1)It comprised of two or more facilities, interconnectedin tandem, to provide a transmission path between a source and a destination.
Telephone Circuit
2)The information transferred in a telephone circuit
Message
3)The circuit used in transferring information in a telephone circuit.
Message Circuit
4)The network bandwidth for a standard voice-band message channel.
4 kHz
5)Unused frequency bands located between information signals.
Guard Bands
6)Effective channel bandwidth for a voice-band message signal.
300 Hz to 3000 Hz
7)The only facility required by all voice-band circuits, as it is the means by which subscriber locations are connected to the local telephone company
Local Subscriber Loop
8)The primary caused of attenuation and phase distortion on a telephone circuit.
Two components
found on local loops:
Loading Coils
Bridge Taps
9)The largest cable used in a local loop, usually 3600 pair of copper wire placed underground or in conduit.
Feeder Cable (F1)
10)A cross-connect point used to distribute the larger feeder cable into smaller distribution cables.
Serving Area Interface
11)A smaller version of a feeder cable containing less wire pairs.
Distribution Cable
12)A device that serves as the demarcation point between local telephone company responsibility and subscriber responsibility for telephone service.
Subscriber or Standard
Network Interface (SNI)
13)The final length of cable pair that terminates at the SNI.
Drop Wire
14)That portion of the local loop that is strung between poles.
Aerial
15)The location where individual cable pairs within a distribution cable are separated and extended to the subscriber's location on a drop wire.
Distribution Cable and Drop Wire Cross Connect Point
16)Adding inductors periodically in series with the wire.
Loading
17)The inductor in loading technique.
Loading Coil
18)An irregularity frequently found in cables serving subscriber location.
Bridge Tap
19)A loss that allows signals to split and propagation down more than one wire introduced by bridge taps.
Bridging Loss
20)Weighting network introduced by AT & T to accomplish equal magnitude of noise signals.
C-Message Weighting
21)The most annoying frequency to human (i.e. the best frequency response).
1000 Hz
22)The basic yardstick used for making power measurements in communications.
Decibel (dB)
23)The optimum level of a test tone on a channel at some point in a communications system. It is used for voice circuits.
Transmission Level Point (TLP)
24)The ratio in dB of the power of a signal at that point to the power the same signal would be at 0 dBm transmission level point.
Transmission Level (TL)
25)The reference for TLP.
0 dBm
26)A parameter equivalent to TLP except it is used as a reference for data transmission.
Data Level Pint (DLP)
27)dBm reference to a zero transmission level point.
dBmO
28)dB reference value for noise reading.
reference noise (rn)
29)dB level of noise with respect to reference noise (- 90 dBm).
dBrn
30)Similar to dBrn except it is the dB value of noise with respect to reference noise using C-message weighting
dBrnc
31)Noise readings taken with a filter that has a flat frequency response from 30 Hz to 3 kHz
dBrn 3 kHz Flat
32)The amount of noise in dBrnc corrected to a 0 TLP
dBrncO
34)Transmission parameters which include terminal impedance, in band and out of band signal power, test signal power and ground isolation.
Interface Parameters
35)Transmission parameters which includes noise measurements, frequency distortion, phase distortion, amplitude distortion and non linear distortion.
Facility Parameters
36)The difference in circuit gain experienced at a particular frequency with respect to the circuit gain of a reference frequency.
Another names attenuation distortion:
· Frequency Response,
· Differential Gain
· 1004-Hz Deviation
Attenuation Distortion
37)An indirect method of evaluating the phase delay characteristics of a circuit.
Envelope Delay Distortion
38)It satisfies the minimum line conditioning requirements
Basic Voice-Band Channel
39)Another name for basic voice-band.
Basic 3002 Channel
40)Specifies the maximum limits for attenuation distortion and envelope delay distortion.
Classifications of C-type:
· C1
· C2
· C3
· C4
· C5
C-type Conditioning
41)Classification of C-type conditioning pertains to two point and multi point circuits.
C1 and C2
42)C-type conditioning used for access lines and trunk circuits associated with private switched networks.
C3
43)C-type conditioning pertains to two point and multi point circuits with a maximum of four stations
C4
44)C-type conditioning pertains to two point circuits only
C5
45)A relatively low-capacity switching machine where the subscribers are generally limited to stations within the same building or building complex.
Private Branch Exchange (PBX)
46)The frequency response of a transmission medium referenced to 1004 Hz test tone.
Attenuation Distortion
47)A requirement for error free data transmission.
Linear Phase vs. Frequency
48)The difference in phase shifts with respect to frequency that signals experience as they propagate through a transmission medium.
Delay Distortion
49)The time delay encountered by a signal as it propagates from source to a destination.
Propagation Time
50)The delay measured in angular units.
Phase Delay
51)The actual time required for a particular frequency to propagate from a source to a destination through a communications channel.
Absolute Phase Delay
52)The time required to propagate a change in an AM envelope through a transmission medium.
Envelope Delay
53)The phase difference at the different carrier frequencies.
Envelope Delay Distortion
55)It sets the minimum requirements for signal to noise ratio and nonlinear distortion.
D-Type Line Conditioning
56)The data transmission rate when D type conditioning is mandatory.
9600 bps
57)Telephone industry standard test tone frequency
1004 Hz
58)Measurement that determine the average weighted rms noise power.
C-message Noise Measurement
59)A communications term that indicates the presence of a signal power comparable to the power of an actual message transmission.
Loaded
60)Characterized by high amplitude peaks of short duration having an approximate flat frequency spectrum
Impulse Noise
61)A sudden, random change in the gain of a circuit resulting in a temporary change in the signal level.
Gain Hit
62)A decrease in circuit gain of more than 12 dB lasting longer than 4 ms.
Dropout
63)A sudden, random changes in the phase of a signal.
Phase Hits (Slips)
64)A form of incidental phase modulation - a continuous, uncontrolled variation in the zero crossings of a signal.
Phase Jitter
65)The presence of one or more continuous, unwanted tones within a message channel.
Single Frequency Interference
66)Unwanted tones within a message channel.
Spurious Tones
67)The frequency of the signal changes during transmission.
Frequency Shift
68)It occurs in coherent SSBSC systems when the received carrier is not reinserted with the exact phase relationship to the received signal as the transmit carrier possessed.
Phase Intercept Distortion
69)It occurs in coherent SSBSC systems when the received carrier is not reinserted with the exact phase relationship to the received signal as the transmit carrier possessed.
Phase Intercept Distortion
70)A four wire circuit an interface.
Hybrid Set
71)Another name for hybrid set.
Terminating Set
72)Any disturbance created in a communications channel by signals in other communications channels.
Crosstalk
73)Annoying and objectionable because the listener senses a real or fancied loss of privacy
Intelligible crosstalk
74)It does not violate privacy, although it can still be annoying.
Unintelligible crosstalk
75)A direct result of nonlinear amplification in analog communications system.
Nonlinear Crosstalk
76)Electromagnetic coupling between two or more physically isolated transmission media.
Coupling Crosstalk
77)Interference caused by inadequate control of the transfer characteristics or transmittance of networks.
Transmittance Crosstalk
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