CHAPTER 11
DIGITAL T-CARRIERS AND MULTIPLEXING
1)Transmission of information from one or more sourceTo one or more destination over the same transmission medium (facility). Multiplexing
2)Unsophisticated form of multiplexing that simplyconstitutes propagating signals from different sources of different cables that are contained within the same trench.
Space-Division Multiplexing
3)Considered as transmission medium. Trench
4)Form of phase-division multiplexing (PDM) where to date channels (the I and Q) modulate the same carrier frequency that has been shifted 90◦ in phase. QPSK
5)Modulates a sine wave carrier. I – Channel Bits
6)Modulates a cosine wave carrier. Q – Channel Bits
7)Three most predominant methods of multiplexing signals.
Time-DivisionMultiplexing; Frequency-Division Multiplexing; Wavelength-Division Multiplexing
8)Transmissions from multiple sources occur on the same but not on the same time.
Time-Division Multiplexing
9)Most prevalent encoding technique used for TDM digital signals. PCM
10)Use an 8-kHz sample rate and an eight-bit PCM code, which produces a 64 kbpsPCM line speed. DS-O Channel
11)Simply an electronically controlled digital switch with two inputs and one outputs.
Multiplexer
12)One eight-bit PCM code from each channel(16 total bits). TDM Frame
13)Time it takes to transmit one TDM frame. Frame Time
14)A communications system that uses digital pulses rather than analog signals to encode information. Digital Carrier System
15)Specifies a digital carrier system using PCM encoded analog signals.
TI or Transmission One
16)Voice band channel bandwidth. 300 Hz to 3000 Hz
17)Special conditioned cables. TI Lines
18)Used to maintain frame and sample synchronization between TDM transmitter & receiver. Framing Bit
19)PCM encoders & decoders with a seven-bit magnitude. Digital Channel Banks
20)Supervision between telephone offices, such as on hook, off hook, dial pulsing, and so forth. Signaling
21)Only seven-bit resolution. Signaling Frame
22)Consist of 24 193 bit frames, totaling 4632 bits, of Format which 24 are framing bits. Extended Super Frame
23)Used for an error detection code. CRC-6( Cyclic Redundancy Checking )
24)Signaling bit in frame 6. A Bit
25)Signaling bit in frame 12. B Bit
26)Signaling bit in frame 18. C Bit
27)Signaling bit in frame 24. D Bit
28)Digital interface that provides the physical connection to a digital carrier network.
Data Service Unit /Channel Service Unit
29)Upgrade from one level in the hierarchy to the next higher level.
Multiplexers /Demultiplexers
30)Provides a convenient place to make patchable inter connects and perform routine maintenance & trouble shooting. Digital Cross Connect
31)Provides frequency shifting for the master group signals. Signal Processor
32)Low quality video transmission for use between non-dedicated subscribers.
Picturephone
33)Identify when transitions occur in the data and whether that transition is from a 1 to a 0 or vice versa. Three-Bit Code
34)First bit of the code. Address Bit
35)Converting standard logic levels. Digital Line Encoding
36)Involves the transmission of only a single nonzero voltage level. Unipolar
37)Two nonzero voltages are involved ( a positive voltage for a logic 1 and an equal-magnitude negative voltage for a logic 0 or vice versa). Bipolar
38)Categorize the type of transmission. Duty Cycle
39)Maintained the entire bit time. Nonreturn to Zero
40)Less than 100% of the bit time. Return to Zero
41)Produces a condition in which a receive may lose its amplitude reference for optimum discrimination between received 1’s & o’s. DC Wandering
42)Popular type of line encoding that produces a strong timing component for clock recovery and does not cause dc wandering. Digital Biphase
43)Uses one cycle of a square wave at 0◦ phase to represent a logic 1 and one cycle of a square wave at 180◦ phase to represent a logic 0. Biphase
44)Used for encoding SMPTE(Society of Motion Picture and Tele vision Engineers) time-code data for recording on videotapes. Biphase M
45)Commonly called the Manchester Code and specified in IEEE standard 802.3 for Ethernet local area networks. Biphase L
46)Forms of delay-modulated codes where a logic 1 condition produces a transition in the middle of the clock pulse, and a logic 0 produces no transition at the end of the clock intervals unless followed by another logic 0. Miller Codes
47)Used for the transmission of PCM-encoded time-division multiplexed digital signals.
T Carriers
48)Filters and shapes the incoming digital signal and raise its power level so that the regenerator circuit can make a pulse-no pulse decision. Amplifier /Equalizer
49)Recovery circuit reproduces the cocking information from the received data and provides the proper timing information to the regenerator so that samples can be made at the optimum time, minimizing the chance of an error occurring. Timing Clock
50)A threshold detector that compares the sampled voltage received to a reference level and determines whether the bit is a logic 1 or a logic 0. Regenerative Repeater
51)Different version of T carriers used in Europe. E-Lines
52)Used for frame alignment pattern and for an alarm channel. Time Slot 0
53)Digital carrier frame synchronization. Added-Digit Framing, Robbed-digit framing, Added-channel framing, Statistical framing, Unique-line code framing
54)Methods of Interleaving PCM transmissions: Bit Interleaving, Word Interleaving
55)Used more often for the transmission of data when they are called asynchronous TDM, intelligent TDM, or simply stat muxs. Statistical Time-Division Multiplexing
56)Large-scale integration (LSI) chip designed for use in the telecommunications industry for private branch exchanges. CODEC
57)Three functions of codec. Analog Sampling; Encoding / Decoding; Digital Companding
58)Used to gate the PCM word onto the PCM highway when an external buffer is used to drive the line. Time Slot Strobe Buffer
59)Data are input and output for a single channel in a short burst. Burst Mode
60)Allows for a flexible data input and output clock frequency. Variable-Data-Rate Mode
61)Data from the PCM highway are clock into the codec on the next eight consecutive negative transitions of DCLKR. Shift Register Mode
62)Multiple sources that originally occupied the same frequency spectrum are each converted to a different frequency. Frequency Division Multiplexing
63)Process is accomplished without synchronization between stations. Stacking
64)AT&T’s communications network is subdivided into 2: Short Haul; Long Haul
65)Basic building block of the FDM Heirarchy. Message Channel
66)Separate signals with different wavelengths in a manner similar to the way filters separate electrical signals of different frequencies. Demultiplexers /Splitters
67)Similar to regular multiplexers and demultiplexers except they are located at intermediate points in the system. Add / Drop Multiplexers / Demultiplexers
68)Direct signals of a particular wavelength to a specific destination while not separating all the wavelengths present on the cable. WDM Routers
69)Enable more efficient utilization of the transmission capabilities of optical fibers by permitting different wavelengths to be combined and separated. WDM Couplers
70)Three basic types of WDM couplers: Diffraction Grating ; Prism ; Dichroic Filter
71)Multiplexing system similar to conventional time division multiplexing. Synchronous Optical Network
72)Has a 51.84-Mbps synchronous frame structure. STS-1
73)Second level of SONET multiplexing. OC-48
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