DIGITAL COMMUNICATION

1.What are the advantages of digital communication/

            -transmission quality high

            -Effect of noise, distortion and interference is less in a communication system.

            -Digital circuits are more reliable and cheaper compared to analog circuits

2.What are the disadvantages of digital communication?

            -Large System Bandwidth

            -System Synchronization

3.What are the performance measure of communication systems?

            -Spectral Efficiency

            -Bit Error Rate

            -Bandwidth Utilization

4.Define Sampling.

            The process of conversion of analog signal into digital signal is called sampling. There are two types of sampling 1.Impulse sampling 2. Natural Sampling

5.What is meant by Alaising effect?

            Alaising effect takes place when the sampling frequency is less than nyquist rate. During this condition the spectrum of sampled signal overlaps itself. So high frequency takes the form of low frequency. This interference is called as aliasing effect.

6.What is meant by quantization?

            The process of transforming continuous samplied amplitude values m(nTs) of a message signal m(t) at time t=nTs into discrete amplitude value mq(nTs) from finite set of possible amplitude is referred to as quantization.

7.What are the types of quantization?

            -Scalar quantization

            -vector quantization

8.Mention the pulse modulation techniques?

            -Pulse Amplitude Modulation

            -Pulse Width Modulation

            -Pulse Position Modulation

9.What are the types of Adaptive Delta modulation?

            -Discrete type

            -Continuous type

10.What is meant by sub band coding?

            Sub band coding is a method of controlling and distributing quantization noise across the signal spectrum.