Flashcards
ECE 521 Quiz 3 REVIEWER
Cards in this deck (71)
- 1It is the transmission of information from one or more sources to one or more destinations over the same medium.Multiplexing
- 2General types of Multiplexing1. Time-Division Multiplexing (TDM)
2. Frequency-Division Multiplexing (FDM)
3. Wavelength-Division Multiplexing (WDM)
4. Phase-Division Multiplexing (PDM)
5. Space-Division Multiplexing (SDM) - 3involves the conversion of standard logic levels to a form more suitable for transmission (e.g. digital waveform).Digital Line Encoding
- 4Factors to consider when selecting a line encoding format1. Transmission voltages and DC component
2. Duty cycle
3. Bandwidth consideration
4. Clock and framing bit recovery
5. Error detection - 5can be categorized either as unipolar (UP) or bipolar (BP).Transmission voltages
- 6transmission of binary data involves transmission of a single nonzero voltage level.Unipolar
- 7transmission of binary data involves transmission of two nonzero voltage levels.Bipolar
- 8The __________ of a binary pulse can be used to categorize the type of transmission.duty cycle
- 9Two types of duty cycle are ______ and _______Nonreturn to Zero (NRZ) and Return to Zero (RZ).
- 10In NRZ, a binary pulse is maintained for the entire bit time.NRZ
- 11In ____, active time of the binary pulse is less than 100% of the bit time.RZ
- 12Some 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 - 13This condition occurs when a long string of 1s (or 0s) causes the receiver to lose its amplitude reference.DC Wandering in NRZ
- 14This would result to misinterpretation of binary data (i.e. 1s may be interpreted as 0s because of the noise margin).DC Wandering in NRZ
- 15The ____________ required to propagate a line-encoded digital signal is equal to the highest fundamental frequency associated with the signal.minimum bandwidth
- 16is based on the fastest transition in the bit sequence.Highest fundamental frequency
- 17When does the fastest transition occur? • In UPNRZ: ________________when alternating 1s and 0s occur
- 18When does the fastest transition occur? • In BPNRZ: ______________when alternating 1s and 0s occur
- 19When does the fastest transition occur? • In UPRZ: ________________when successive logic 1s occur
- 20When does the fastest transition occur? • In BPRZ: __________________when successive logic 1s or success logic 0s occur
- 21When does the fastest transition occur? • In BPRZ-AMI: ___________________when two or more successive logic 1s occur
- 22Highest fundamental frequency for UPNRZ has one cycle for _____ bit timestwo or 2
- 23Highest fundamental frequency for BPNRZ has one cycle for ____ bit times.two or 2
- 24Highest fundamental frequency for UPRZ has one cycle for ___ bit time.one or 1
- 25Highest fundamental frequency for BPRZ has one cycle for ____ bit time.one or 1
- 26Highest fundamental frequency for BPRZ-AMI has one cycle for ___ bit timestwo or 2
- 27___________ is easily maintained if there are sufficient transitions in the data waveform. Else, lack of transitions would be inadequate for clock recovery.Synchronization
- 28When does lack of transitions happen? • In UPNRZ: __________________long string of 1s or long string of 0s
- 29When does lack of transitions happen? • In BPNRZ: _______________long string of 1s or long string of 0s
- 30When does lack of transitions happen? • In UPRZ: ________________long string of 0s only
- 31When does lack of transitions happen? • In BPRZ: __________________none (best for clock recovery)
- 32When does lack of transitions happen? • In BPRZ-AMI: __________________long string of 0s only
- 33With 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
- 34This 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)
- 35two patterns that are substituted in B8ZS+ - 0 - + 0 0 0
- + 0 + - 0 0 0 - 36Similar 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)
- 37two patterns that are substituted in B6ZS0 + - 0 - +
0 - + 0 + - - 38Similar 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)
- 39four patterns that are substituted in B3ZS00-
-0-
00+
+0+ - 40is sometimes called the Manchester code or diphase.Digital biphase
- 41It 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
- 42Digital biphase represents logic ____ using one square wave cycle at 0° phase1
- 43Digital biphase represents logic ____ using one square wave cycle at 180° phase0
- 44transmissions from multiple sources occur on the same facilities but not on the same time.Time-Division Multiplexing (TDM)
- 45Transmissions are interleaved in the time domain (using _________).time slots
- 46TDM is predominantly used for ______ signals.digital
- 47A ___________ is a communications system that uses digital pulse rather than analog signals to encode information.digital carrier system
- 48AT&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
- 49In 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
- 50D-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
- 51Types of digital channel banks1. D1
2. D2
3. D3
4. D4
5. D5 - 52Type/s of digital channel banks that uses TDM frameD
- 53Type/s of digital channel banks that uses superframe (SF)D2, D3, D4
- 54Type/s of digital channel banks that uses extended superframe (ESF)D5
- 55This was used by early T1 carrier systems. This utilized companding and u = 10D1 Channel Bank
- 56In D1, each TDM frame contains ___ channels with one framing bit added at the start of the frame.24
- 57Versions 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) - 58Line speed , Frame rate, and Channel speed of 7-bit magnitude only PCM codes1.352 Mbps ; 8 kbps ; 56 kbps
- 59Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes1.352 Mbps ; 8 kbps ; 56 kbps
- 60Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes with signaling bit1.352 Mbps ; 8 kbps ; 56 kbps
- 61In D2 and D3 channel banks, every group of 12 TDM frames is called a _______________.SF or Superframe
- 62Superframe is also known as ___________.D4 Framing
- 63Similar 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
- 64However, _________ bits are no longer simply alternating 1s and 0s.framing
- 65Unlike D1, signaling bit was only inserted every ____ frames.6
- 66Signaling bit is inserted using ________ signaling.robbed-bit
- 67This widely implemented the superframe formatD4 Channel Bank
- 68Unlike predecessors, D4 channel banks time-division multiplexes ___ voice-band telephone channels.48
- 69Essentially, SF = ____ TDM frames for D4 channel banks.2
- 70A D4 (DS1-C) frame contains _____ bits.394
- 71Line speed of UST ECE | engrjbr 2017 D4 Channel Bank3.152 Mbps