Fechar
It is the transmission of information from one or more sources to one or more
destinations over the same medium.
General types of Multiplexing
involves the conversion of standard logic levels to a form more suitable for transmission (e.g. digital waveform).
Factors to consider when selecting a line encoding format
can be categorized either as unipolar (UP) or bipolar (BP).
transmission of binary data involves transmission of a single
nonzero voltage level.
transmission of binary data involves transmission of two nonzero
voltage levels.
The __________ of a binary pulse can be used to categorize the type of
transmission.
Two types of duty cycle are ______ and _______
In NRZ, a binary pulse is maintained for the entire bit time.
In ____, active time of the binary pulse is less than 100% of the bit time.
Some line-encoding formats based on the transmission level and duty cycle:
This condition occurs when a long string of 1s (or 0s) causes the receiver to lose its amplitude reference.
This would result to misinterpretation of binary data (i.e. 1s may be interpreted as 0s because of the noise margin).
The ____________ required to propagate a line-encoded digital signal is
equal to the highest fundamental frequency associated with the signal.
is based on the fastest transition in the bit
sequence.
When does the fastest transition occur?
• In UPNRZ: ________________
When does the fastest transition occur?
• In BPNRZ: ______________
When does the fastest transition occur?
• In UPRZ: ________________
When does the fastest transition occur?
• In BPRZ: __________________
When does the fastest transition occur?
• In BPRZ-AMI: ___________________
Highest fundamental frequency for UPNRZ has one cycle for _____ bit times
Highest fundamental frequency for BPNRZ has one cycle for ____ bit times.
Highest fundamental frequency for UPRZ has one cycle for ___ bit time.
Highest fundamental frequency for BPRZ has one cycle for ____ bit time.
Highest fundamental frequency for BPRZ-AMI has one cycle for ___ bit times
___________ is easily maintained if there are sufficient transitions in the data waveform. Else, lack of transitions would be inadequate for clock recovery.
When does lack of transitions happen?
• In UPNRZ: __________________
When does lack of transitions happen?
• In BPNRZ: _______________
When does lack of transitions happen?
• In UPRZ: ________________
When does lack of transitions happen?
• In BPRZ: __________________
When does lack of transitions happen?
• In BPRZ-AMI: __________________
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.
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.
two patterns that are substituted in B8ZS
Similar to B8ZS, this method ensures that sufficient transitions occur in the data
stream when there are successive zeros. Typically applied to T2 system.
two patterns that are substituted in B6ZS
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.
four patterns that are substituted in B3ZS
is sometimes called the Manchester code or diphase.
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 represents logic ____ using one square wave cycle at 0° phase
Digital biphase represents logic ____ using one square wave cycle at 180° phase
transmissions from multiple sources occur on the same facilities but not on the same time.
Transmissions are interleaved in the time domain (using _________).
TDM is predominantly used for ______ signals.
A ___________ is a communications system that uses digital pulse rather than analog signals to encode information.
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 _______.
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.
D-type (digital) channel banks perform these functions in the PCM-TDM system:
(a) _______, (b) _________ and (c) __________ of the 24 voice-band channels.
Types of digital channel banks
Type/s of digital channel banks that uses TDM frame
Type/s of digital channel banks that uses superframe (SF)
Type/s of digital channel banks that uses extended superframe (ESF)
This was used by early T1 carrier systems. This utilized companding and u = 10
In D1, each TDM frame contains ___ channels with one framing bit added at the
start of the frame.
Versions of D1 Channel Bank
Line speed , Frame rate, and Channel speed of 7-bit magnitude only PCM codes
Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes
Line speed , Frame rate, and Channel speed of 7-bit sign-magnitude PCM codes with signaling bit
In D2 and D3 channel banks, every group of 12 TDM frames is called a
_______________.
Superframe is also known as ___________.
Similar to D1, each TDM frame has 24 channels and the framing bit occurs at the
start of every TDM frame.
However, _________ bits are no longer simply alternating 1s and 0s.
Unlike D1, signaling bit was only inserted every ____ frames.
Signaling bit is inserted using ________ signaling.
This widely implemented the superframe format
Unlike predecessors, D4 channel banks time-division multiplexes ___ voice-band
telephone channels.
Essentially, SF = ____ TDM frames for D4 channel banks.
A D4 (DS1-C) frame contains _____ bits.
Line speed of UST ECE | engrjbr 2017
D4 Channel Bank
