The Islamic University of Gaza

Engineering Faculty

Department of Computer Engineering

Fall 2017

Data com. Discussion ECOM4411

Instructor: Dr. Aiman Abu Samra

T.A.: Eng. Muath i.Al Nabris

CH5:

Analog Transmission

2

Exercises:

a. ASK changes the amplitudeof the carrier. b.FSK changes the frequencyof the carrier. c. PSK changes the phase of the carrier. d.QAM changes both the amplitudeand the phaseof the carrier.

We can say that the most susceptible technique is ASKbecause the amplitude is more affected by noise thanthe phase or frequency.

(2000 bps) = 2000 baud×S =(1/1) →2 = 1 2r = log a. (4000 bps) = 4000 baud×S =(1/1) →2 = 1 2r = log b.

(6000 bps) = 3000 baud×S =(1/2) →4 = 2 2r = log c. (36,000 bps)= 6000 baud×S =(1/6) →64 = 6 2d. r =log.

3

Lto calculate the value of r for each case2We use the formula r = log

4 = 22a.log 8 = 32b.log 4= 22c.log 128 = 72logd.

We use the formula B = (1 + d) ×(1/r) ×N, but first we need to calculate the value of r for each case.

a.r = 1 → B=(1 + 1) ×(1/1) ×(4000 bps) = 8000 Hz b.r = 1 → B =(1 + 1) × (1/1) ×(4000 bps) + 4 KHz = 8000 Hz c. r =2 → B =(1 + 1) × (1/2) ×(4000 bps)= 2000 Hz d.r = 4 →B =(1 + 1) × (1/4) ×(4000 bps) = 1000 Hz

4

5 = 10 KHz×B = 2 ×= 2 AMa. B

5 = 60 KHz ×(1 + 5) ×B = 2 ×) β(1 + ×= 2 FMb. B 5 = 20 KHz ×(1 + 1) ×B = 2 ×) β(1 + ×= 2 PMc.B

We calculate the number of channels, not the number of coexisting stations

.a.n =(1700 - 530) KHz / 10 KHz = 117 b.n = (108 - 88) MHz / 200 KHz = 100

Good luck