ECE 23-Problem set 2

False (G.810)

In the G.890 standard, jitter is defined as phase variation with frequency components greater than or equal to 10 Hz.

False

In NRZ-I, the level of the voltage determines the value of the bit, while in NRZ-L, the inversion or the lack of inversion determines the value of the bit.

True

For an efficient digital communication system, the pulse rate must be always lower than or equal to the data rate (or bitrate)

False (N/2)

In NRZ-L, the average signal rate is 2N Baud, while NRZ-I have an average signal rate of N-2 Baud.

True

A line coding scheme without a DC component is easier to transmit compared to different coding scheme with both AC and DC components.

True

In Manchester and Pseudoternary encoding, the signal transition at the middle of the bit is used for synchronization

Non-return-to-zero level

Which encoding method below can be used for application that don’t require precise synchronization?

High or “1”

In AMI coding scheme a “mark” means a logic value of

disparity

This term describes the difference in the number of transmitted “low” and the number of transmitted “high” in a binary transmission system.

AMI (ALternate Mark Inversion)

This line encoding technique have a DC component and does not have self-synchronization for long strings of 0’s

B8ZS

Which scrambling techniques eight consecutive zeros with the bit pattern 000VB0VB

HDB3

Which scrambling technique substitutes four consecutives zeros with 000v or B00v, depending on the number of non-zero pullses after the last substitutions?

4DPAM5

Which of the following coding schemes uses a five signal-level output ?

Block coding

What is the other term that refer to as MB/NB coding because it replaces each m-bit group code with a n-bit group code?

Line Coding

What do you call the process of converting digital data to digital signals?

data element

is the smallest entity that can represent a piece of information, also known as a bit.

zero, positive and negative

When using a bipolar encoding method, what are the possible output signal levels or voltages?

bits to digital signal

Which of the following most accurately describes what type of conversion is performed in line coding?

Digital Transmission

The sending of information over a physical communications media in the form of digital signals.

Null modem

Is a communication method to directly connect two DTEs

Data Communications Equipment

DCE

Data Terminal Equipment

DTE

Two-level encoding

The signal can only take on a strictly negative or strictly positive value (-X and zero) or (+X and zero); where X represents a value of the physical quantity being used to transport the signal)

Three-level encoding

The signal can take on a strictly negative, null/zero or strictly positive value (-X or 0 or +X)

Biphase encoding or Phase Encode

Manchester encoding, also called

RZ encoding (Retuen to zero)

after a data is sent, whether 1 or 0, the signal goes back to zero before sending another data.

NRZ encoding (Non Return-to-Zero)

It transforms the 0s into +X and the 1s into -X , as a result, the receiver can determine whether a signal is present or not.

Coded Mark Inversion

It encodes zero bits as a half bit time of zero followed by a half bit time of one, and while one bits are encoded as a full bit time of a constant level.

2B1Q

Two binary and one quaternary

Scrambling

Solves Problem with long strings of 0’s, which can be a cause for loss of synchronization

Jitter

is defined in the ITU-T G.810 standard as phase variation with frequency components greater than or equal to 10 Hz

Wander

Is defined as phase variations at a rate less than 10 Hz

AMI (ALternate Mark Inversion)

Commonly used for long distance communication, it has a synchronization problem when a long sequence of 0’s present in the data

signal element

In digital communication a,_______ is the shortest unit(timewise) of a digital signal.

RZ (Return to Zero)

Does not go back to zero at the middle of the bit, a signal goes into a neutral or rest condition before transmitting the neat bit of information.

Unipolar scheme

all the levels are on the side of the tie axis, either above or below.

Polar Scheme

The voltage are on both sides all of the time axis. the voltage level for 0 can be positive while the voltage level for 1 can be negative.