Analog & Digital Communication (IT-404) - Important Questions

Draw the block diagram of a basic communication system and explain the function of each block.

Differentiate between energy and power signals. Classify the standard signals - unit step, ramp, signum and impulse - as energy or power signals with justification.

Define linear / non-linear, time-invariant / time-variant, causal / non-causal and stable / unstable systems with one example each.

Find the Fourier Transform of the gate function, unit step function and delta (impulse) function.

Explain the block diagram and working of a superheterodyne receiver, including sensitivity and selectivity.

Explain the generation of AM using square-law modulator with circuit diagram, waveforms and working.

A carrier of 100 V peak is amplitude modulated to a depth of 50%. Calculate modulation index, sideband frequencies, bandwidth, sideband power, total power delivered to load and transmission efficiency.

Define and explain frequency deviation, modulation index and deviation ratio in FM.

Explain the direct and indirect methods of FM generation with block diagrams, working principles and advantages.

Explain the operation of the Foster-Seeley discriminator as an FM demodulator with schematic/circuit diagram and phasor diagrams.

State and prove the sampling theorem for low-pass signals, including Nyquist rate and effect of undersampling (aliasing).

Explain Delta Modulation (DM) and Adaptive Delta Modulation (ADM) in detail, including merits and demerits.

Explain the working of a PCM system with block diagram. What is quantization error? Explain.

With block diagrams, explain the generation and detection of Quadrature Amplitude Modulation (QAM). Explain 8-QAM operation with constellation diagram.

Explain the concept and working of DPSK. How does it differ from BPSK in terms of synchronization? Explain receiver decoding.

Describe BPSK modulation, derive its signal equation, explain its bandwidth, and explain coherent detection / working of BPSK transmitter and receiver with diagrams.