Digital Communication

The binary data 0 1 1 1 0 0 1 0 1 are applied to the input of a modified duo binary system:
i) Construct the modified duo binary coder output and corresponding receiver output without a precoder.
ii) Suppose that due to error in transmission, the level produced by the third digit is reduced to zero. Construct a new receiver output.

A slow FH/MFSK system has the following parameters:
The number of bits/MFSK symbol = 4
The number of MFSK symbols per hop = 6
Calculate processing gain of the system.

Explain properties of PN sequence.

What is spread spectrum technique? How are they classified?

Show that the probability of bit error of a matched filter receiver is given by

Draw and explain the block diagram of correlation receiver.

Consider the signal as given below in Figure below.

Find an orthonormal basis for these set of signals using Gram-Schmidt orthogonalization procedure.

Write a note on Gram-Schmidt orthogonalization procedure.

A binary data is transmitted over an AWGN channel using binary phase shill keying at the rate of 1 Mbps. It is desired to have average probability of error . Noise power spectral density is . Determine the average carrier power required at the receiver input, if the detector is of coherent type. Take erfc(3.5) = 0.00025.

With neat block diagram, explain DPSK transmitter and receiver. Illustrate the generation of differentially encoded sequence for the binary input sequence 0 0 1 0 0 1 1 0 0 1 1 1 1 0.

With a neat block diagram, explain the concept of adaptive equalization.

Explain sampling theorem of low pass signals and derive the interpolation formula.

What is correlative coding? Explain duo binary coding with and without precoding.

Derive an expression for power spectral density of bipolar NRZ format and plot the same with respect to frequency.

For a binary sequence 1 1 1 0 0 0 1 1 0 1 0 1 draw the digital format waveforms corresponding to:
i) Bipolar NRZ waveform and
ii) 8-ary signaling waveform.

Explain the principles of delta modulator. With relevant figure and mathematical expressions, explain the functioning of DM transmitter and receiver.

With a neat block diagram and waveform, explain time division multiplexing.

For a binary PCM signal, determine L if the compression parameter and the minimum , dB = 45 dB. Determine the  dB with this value of L.

Derive the expression for signal to quantization noise ratio (SNR) and show that for uniform quantization, each bit in the codeword of a PCM contributes 6 dB to SNR.

A band pass signal g(t) with a spectrum shown in the following figure is ideally sampled. Sketch the spectrum of sampled signal at . Indicate if and how the signal can be recovered.

A low pass signal x(t) has spectrum X(F) given by,

Sketch the spectrum X8(t) for |f |<200 Hz if (t) is ideally sampled at