ECE 521 Quiz 3 REVIEWER

Pregunta	Respuesta
It is the transmission of information from one or more sources to one or more destinations over the same medium.	Multiplexing
General types of Multiplexing	1. Time-Division Multiplexing (TDM) 2. Frequency-Division Multiplexing (FDM) 3. Wavelength-Division Multiplexing (WDM) 4. Phase-Division Multiplexing (PDM) 5. Space-Division Multiplexing (SDM)
involves the conversion of standard logic levels to a form more suitable for transmission (e.g. digital waveform).	Digital Line Encoding
Factors to consider when selecting a line encoding format	1. Transmission voltages and DC component 2. Duty cycle 3. Bandwidth consideration 4. Clock and framing bit recovery 5. Error detection
can be categorized either as unipolar (UP) or bipolar (BP).	Transmission voltages
transmission of binary data involves transmission of a single nonzero voltage level.	Unipolar
transmission of binary data involves transmission of two nonzero voltage levels.	Bipolar
The __________ of a binary pulse can be used to categorize the type of transmission.	duty cycle
Two types of duty cycle are ______ and _______	Nonreturn to Zero (NRZ) and Return to Zero (RZ).
In NRZ, a binary pulse is maintained for the entire bit time.	NRZ
In ____, active time of the binary pulse is less than 100% of the bit time.	RZ
Some line-encoding formats based on the transmission level and duty cycle:	1. UPNRZ 2. BPNRZ 3. UPRZ 4. BPRZ 5. BPRZ-AMI (Alternate mark inversion) 6. B8ZS 7. B6ZS 8. B3ZS 9. Digital Biphase
This condition occurs when a long string of 1s (or 0s) causes the receiver to lose its amplitude reference.	DC Wandering in NRZ
This would result to misinterpretation of binary data (i.e. 1s may be interpreted as 0s because of the noise margin).	DC Wandering in NRZ
The ____________ required to propagate a line-encoded digital signal is equal to the highest fundamental frequency associated with the signal.	minimum bandwidth
is based on the fastest transition in the bit sequence.	Highest fundamental frequency
When does the fastest transition occur? • In UPNRZ: ________________	when alternating 1s and 0s occur
When does the fastest transition occur? • In BPNRZ: ______________	when alternating 1s and 0s occur
When does the fastest transition occur? • In UPRZ: ________________	when successive logic 1s occur
When does the fastest transition occur? • In BPRZ: __________________	when successive logic 1s or success logic 0s occur
When does the fastest transition occur? • In BPRZ-AMI: ___________________	when two or more successive logic 1s occur
Highest fundamental frequency for UPNRZ has one cycle for _____ bit times	two or 2
Highest fundamental frequency for BPNRZ has one cycle for ____ bit times.	two or 2
Highest fundamental frequency for UPRZ has one cycle for ___ bit time.	one or 1
Highest fundamental frequency for BPRZ has one cycle for ____ bit time.	one or 1
Highest fundamental frequency for BPRZ-AMI has one cycle for ___ bit times	two or 2
___________ is easily maintained if there are sufficient transitions in the data waveform. Else, lack of transitions would be inadequate for clock recovery.	Synchronization
When does lack of transitions happen? • In UPNRZ: __________________	long string of 1s or long string of 0s
When does lack of transitions happen? • In BPNRZ: _______________	long string of 1s or long string of 0s
When does lack of transitions happen? • In UPRZ: ________________	long string of 0s only
When does lack of transitions happen? • In BPRZ: __________________	none (best for clock recovery)
When does lack of transitions happen? • In BPRZ-AMI: __________________	long string of 0s only
With BPRZ-AMI encoding, an error in any bit causes a/an _____________ (BPV) or the reception of two or more consecutive logic 1s with the same polarity.	bipolar violation
This ensures that sufficient transitions occur in the data stream (aka ones density) by substituting a logic 1 when there are several succeeding logic 0s. System must have a mechanism for monitoring the logic values. Typically applied to T1 system.	Binary Eight Zero Substitution (B8ZS)
two patterns that are substituted in B8ZS	+ - 0 - + 0 0 0 - + 0 + - 0 0 0
Similar to B8ZS, this method ensures that sufficient transitions occur in the data stream when there are successive zeros. Typically applied to T2 system.	Binary Six Zero Substitution (B6ZS)
two patterns that are substituted in B6ZS	0 + - 0 - + 0 - + 0 + -
Similar to B8ZS and B6ZS, this method ensures that sufficient transitions occur in the data stream when there are successive zeros. Typically applied to T3 system.	Binary Three Zero Substitution (B3ZS)
four patterns that are substituted in B3ZS	00- -0- 00+ +0+
is sometimes called the Manchester code or diphase.	Digital biphase
It is a popular type of line encoding that produces a strong timing component for clock recovery and does not cause DC wandering. It has no built-in error detection mechanism. It has an average DC voltage of 0V assuming an equal probability of 1s and 0s.	Digital biphase
Digital biphase represents logic ____ using one square wave cycle at 0° phase	1
Digital biphase represents logic ____ using one square wave cycle at 180° phase	0
transmissions from multiple sources occur on the same facilities but not on the same time.	Time-Division Multiplexing (TDM)
Transmissions are interleaved in the time domain (using _________).	time slots
TDM is predominantly used for ______ signals.	digital
A ___________ is a communications system that uses digital pulse rather than analog signals to encode information.	digital carrier system
AT&T’s (Bell system’s) ____ Digital Carrier System is recognized as the North American Digital Multiplexing Standard since 1963 and is recognized by ITU-T as Recommendation _______.	T1 ; G.733
In T1 Digital Carrier System, ____ voice-band channels with ideal bandwidth of 4000 Hz are PCM-encoded and multiplexed for transmission over a single metallic wire pair or fiber transmission line.	24
D-type (digital) channel banks perform these functions in the PCM-TDM system: (a) _______, (b) _________ and (c) __________ of the 24 voice-band channels.	sampling ; encoding ; multiplexing
Types of digital channel banks	1. D1 2. D2 3. D3 4. D4 5. D5
Type/s of digital channel banks that uses TDM frame	D
Type/s of digital channel banks that uses superframe (SF)	D2, D3, D4
Type/s of digital channel banks that uses extended superframe (ESF)	D5
This was used by early T1 carrier systems. This utilized companding and u = 10	D1 Channel Bank
In D1, each TDM frame contains ___ channels with one framing bit added at the start of the frame.	24
Versions of D1 Channel Bank	• 7-bit magnitude-only PCM code • 7-bit sign-magnitude PCM code • 7-bit sign-magnitude PCM code with signaling bit (essentially 8 bits)
Line speed , Frame rate, and Channel speed of 7-bit magnitude only PCM codes	1.352 Mbps ; 8 kbps ; 56 kbps
Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes	1.352 Mbps ; 8 kbps ; 56 kbps
Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes with signaling bit	1.352 Mbps ; 8 kbps ; 56 kbps
In D2 and D3 channel banks, every group of 12 TDM frames is called a _______________.	SF or Superframe
Superframe is also known as ___________.	D4 Framing
Similar to D1, each TDM frame has 24 channels and the framing bit occurs at the start of every TDM frame.	D2 and D3 Channel Banks
However, _________ bits are no longer simply alternating 1s and 0s.	framing
Unlike D1, signaling bit was only inserted every ____ frames.	6
Signaling bit is inserted using ________ signaling.	robbed-bit
This widely implemented the superframe format	D4 Channel Bank
Unlike predecessors, D4 channel banks time-division multiplexes ___ voice-band telephone channels.	48
Essentially, SF = ____ TDM frames for D4 channel banks.	2
A D4 (DS1-C) frame contains _____ bits.	394
Line speed of UST ECE \| engrjbr 2017 D4 Channel Bank	3.152 Mbps

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