tutorial 5 - wordpress.comtutorial 5 prebared by t. a,najedalmutairi 1. what is differential...

Tutorial 5

Prebared by T.A,Najed Almutairi

1. What is differential encoding?


Ans q (1)

differential coding is a technique used to provide unambiguous

signal reception when using some types of modulation. It makes

data to be transmitted to depend not only on the current signal

state (or symbol), but also on the previous one.

The common types of modulation that require differential coding

include phase shift keying and quadrature amplitude modulation.


https://en.wikipedia.org/wiki/Modulation

https://en.wikipedia.org/wiki/Phase_shift_keying

https://en.wikipedia.org/wiki/Quadrature_amplitude_modulation

2.What function does a modem

perform


Ans q (2)

A modem converts digital data to an analog signal so

that it can be transmitted over an analog medium like

Optical fiber and unguided media.


3.How are binary values

represented in amplitude shift

keying, and what is the limitation of

this approach?


Ans q (3)

In Amplitude Shift Keying (ASK), the binary values are represented by two

different amplitudes of the carrier frequencies.

one amplitude is ZERO, it’s represented by the presence, at constant

amplitude of the carrier.

second amplitude is absence of the carrier signal .A cos (2 2*pi*f*t)

represented by binary 1.


Ans q (3)

The ASK limitations are :

used to transmit digital data over optical fiber.

It is a susceptible to sudden gain changes.

inefficient modulation technique.


4.Define analog transmission.


Ans q (4)

analog transmission refers to the

transmission of analog signals using a

band-pass channel. Baseband digital or

analog signals are converted to a complex

analog signal with a range of frequencies

suitable for the channel


5. Define carrier signal and its role

in analog transmission


Ans q (5)

A carrier is a single-frequency signal that has one of its

characteristics (amplitude, frequency, or phase) changed

to represent the baseband signal.


6.Which characteristics of an analog signal are changed to

represent the digital signal in each of the following digital-

to-analog conversion?

a. ASK b. FSK c. PSK


Ans q (6)

1. Amplitude shift keying (ASK), changes the amplitude

of the carrier

2. Frequency shift keying (FSK), changes the frequency of

the carrier.

3. Phase shift keying (PSK),changes the phase of the

carrier.


7.Define analog-to-analog

conversion?


Ans q (7)

Process of changing one of the characteristics of an analog signal to

represent the instantaneous of amplitude of a baseband signal .

Another called” modulation of an analog signal ”;the

baseband analog signal modulates the carrier to create a

broadband analog signal .


8. Which characteristics of an analog signal

are changed to represent the lowpass

analog signal in each of the following

analog-to-analog conversions?

a. AM

b. FM

c. PM


Ans q (8)

a.AM changes the amplitude of the

carrier

b. FM changes the frequency of the

carrier

c. PM changes the phase of the carrier


9.Which of the three analog-to-analog

conversion techniques (AM, FM, or PM) is

the most susceptible to noise? Defend your

answer


Ans q (9)

We can say that the most susceptible technique is

AM because the amplitude is more affected by

noise than the phase or frequency.


للرسمالتاليهالقواعداعتماديتم


p(1)Given the bit pattern 01100,

encode this data using ASK, BFSK,

and BPSK.


Ans p (1)


p (2)

Given the bit pattern 101001000011,

encode this data using MFSK assume each

signalling element represents with 3-bits.


Ans p (2)2^3 , M= 8


p (3)

For the bit stream 0100111001, encode

this data using DPSK.


Ans p (3)

o A binary 0 is represented by sending a signal burst of the same

phase as the previous signal burst sent.

o A binary 1 is represented by sending a signal burst of opposite

phase to the preceding one

o 0100111001


p (4)

Assume a stream of ten 1’s(1111111111).

Encode the stream using the following

schemes: NRZ-I, AMI, Manchester,

Differential Manchester


بداية السيقنال معطاه بالسؤالتحديديتممالحظه

NRZ-I

AMI

Manchester,

Differential

Manchester


p (5)

5- For the Manchester encoded binary

stream of the following, extract the clock

information and the data sequence.


p (5),ans


p (6)

Consider a stream of binary data consisting of a long

sequence of 1s, followed by a zero, followed by a long

sequence of 1s. Preceding bit and level is indicated

within parentheses. Draw the waveforms for NRZI

(high), AMI (1 as negative voltage), and pseudo-ternary

(0 as negative voltage).


p (6),ans

NRZI (high),

AMI (1 negative),

pseudo-ternary (0 as negative).

pseudo-ternary


p (7)

The AMI waveform representing a sequence

0100101011 is transmitted over a noisy

channel. The received waveform with a

single error is shown in the following page.

Locate the error with justification.


p (7),ans

Error is 7 position ,there’s negative value .


p (8)•The analog waveform shown in the following figure is to be delta modulated.

•The sampling period and the step size are indicated by the grid. The first DM output is also shown.

•Give the DM output for the complete signal.


p (8),ans

delta modulated:

up: 1 ,down:0


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