Tutorial 5. Prebared by T.A,Najed Almutairi

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Doreen McLaughlin
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1 Tutorial 5

2 1. What is differential encoding?

3 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.

4 2.What function does a modem perform

5 Ans q (2) A modem co verts digita data to a a a og sig a so that it ca be tra smitted over a a a og medium ike Optica fiber a d u guided media.

6 3.How are binary values represented in amplitude shift keying, and what is the limitation of this approach?

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

7 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.

8 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.

9 4.Define analog transmission.

10 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

11 5. Define carrier signal and its role in analog transmission

12 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.

13 6.Which characteristics of an analog signal are changed to represent the digital signal in each of the following digitalto-analog conversion? a. ASK b. FSK c. PSK

14 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.

15 7.Define analog-to-analog conversion?

16 Ans q (7) Process of changing one of the characteristics of an analog signal to represent the instantaneous of amplitude of a baseband signal. A other ca ed modu atio of a a a og sig a ;the baseba d a a og sig a modu ates the carrier to create a broadba d a a og sig a.

17 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

18 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

19 9.Which of the three analog-to-analog conversion techniques (AM, FM, or PM) is the most susceptible to noise? Defend your answer

20 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.

21 اعتماد يتم القواعد التاليه للرسم

22 p(1)given the bit pattern 01100, encode this data using ASK, BFSK, and BPSK.

23 Ans p (1)

24 p (2) Given the bit pattern , encode this data using MFSK assume each signalling element represents with 3-bits.

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

26 p (3) For the bit stream , encode this data using DPSK.

27 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

28 p (4) Assume a stream of ten 1 s( ). Encode the stream using the following schemes: NRZ-I, AMI, Manchester, Differential Manchester

29 مالحظه تحديد يتم بداية السيقنال معطاه بالسؤال NRZ-I AMI Manchester, Differential Manchester

30 p (5) 5- For the Manchester encoded binary stream of the following, extract the clock information and the data sequence.

31 p (5),ans

32 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).

33 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.

34 p (7) The AMI waveform representing a sequence is transmitted over a noisy channel. The received waveform with a single error is shown in the following page. Locate the error with justification.

35 p (7),ans Error is 7 position,there s negative value.

36 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.

37 p (8),ans delta modulated: up: 1,down:0

Class 4 ((Communication and Computer Networks))

Class 4 ((Communication and Computer Networks)) Lesson 5... SIGNAL ENCODING TECHNIQUES Abstract Both analog and digital information can be encoded as either analog or digital signals. The particular encoding