Chapter 11: Digital T-Carriers and Multiplexing - Review Notes

This is the summary notes of the important terms and concepts in Chapter 11 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.

CHAPTER 11

DIGITAL T-CARRIERS AND MULTIPLEXING

Items	Definitions	Terms
1	Transmission of information from one or more source To one or more destination over the same transmission medium (facility).	Multiplexing
2	Unsophisticated form of multiplexing that simply constitutes 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-Division Multiplexing; 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 kbps PCM 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 which 24 are framing bits.	Extended Super Frame Format
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.	Non-return 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 & 0’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 Hierarchy.	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

Complete List of Reviewers in Electronic Communications System per Chapter

Reviewer in Electronic Communications System by Wayne Tomasi

Important List of Communications Engineering Materials

Communications Engineering Coaching Materials

Series of Communications Engineering Exams: ECE Pre-Board

Series of Questions and Answers in Communications Engineering

Multiple Choice Questions in Data Communications and Networking

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