Forouzan Chapter 4 Identification

Question 1

we discuss _ techniques,

methods which convert digital data to digital signals.

Answer 1

digital-to-digital conversion

Question 2

The conversion

involves three techniques: _, _, and _.

Answer 2

line coding,block coding,scrambling

Question 3

_ is the process of converting digital data to a digital signal.

Answer 3

Line coding

Question 4

We can roughly divide line coding schemes into five broad categories: ,,,,and _.
.

Answer 4

unipolar,polar, bipolar, multilevel, multitransition

Question 5

Block coding provides _ to ensure _ and inherent error detection.

Answer 5

redundancy,synchronization

Question 6

Block coding provides redundancy to ensure _ and _.

Answer 6

synchronization,inherent error detection

Question 7

Block coding is normally referred to as _; it replaces each m-bit group with an n-bit group.

Answer 7

mB/nB coding

Question 8

_ provides synchronization without increasing the number of bits. Two

Answer 8

Scrambling

Question 9

common scrambling techniques are _ and _.

Answer 9

B8ZS,HDB3

Question 10

The most common technique to change an analog signal to digital data (_)
is called _.

Answer 10

digitization,pulse code modulation (PCM)

Question 11

The first step in PCM is _. The analog signal is sampled every Ts s, where Ts
is the sample interval or period.

Answer 11

sampling

Question 12

The inverse of the sampling interval is called the

_ and denoted by fs, where fs =l/Ts.

Answer 12

sampling rate or sampling frequency

Question 13

There are

three sampling methods-_, , and.

Answer 13

ideal,natural, flat-top

Question 14

According to the_, to reproduce the original analog signal, one
necessary condition is that the sampling rate be at least twice the highest frequency
in the original signal.

Answer 14

Nyquist theorem

Question 15

Other sampling techniques have been developed to reduce the complexity of PCM.
The simplest is _.

Answer 15

delta modulation

Question 16

PCM finds the value of the signal amplitude for

each sample; DM finds the _ from the previous sample.

Answer 16

change

Question 17

While there is only one way to send parallel data, there are three subclasses of
serial transmission: _, _, and _.

Answer 17

asynchronous,synchronous,isochronous

Question 18

In _, we send 1 start bit (0) at the beginning and 1 or

more stop bits (1 s) at the end of each byte.

Answer 18

asynchronous transmission

Question 19

In _, we send bits one after another without start or stop

bits or gaps. It is the responsibility of the receiver to group the bits.

Answer 19

synchronous transmission

Question 20

The _ provides synchronized for the entire stream of bits must. In
other words, it guarantees that the data arrive at a fixed rate.

Answer 20

isochronous mode