Q.2 A.

Write Note on Ring Modulator for Amplitude Modulation with diagram and waveforms.

B. Write Note on Envelope Detector for AM waves.

C.

Write Quadrature Amplitude Modulation for AM waves in detail with Diagram.

D.

Discuss Indirect FM Transmitter with Detailed Diagram.

D. Discuss Pre-emphasis and De-emphasis filters in detail.

Q.3

A. Discuss Collector Modulator for AM with Circuit and Waveforms.

B. Explain Superheterodyne AM Receiver with Block Diagram and explain its each block with its function.

There are five sections to a superheterodyne receiver:1. RF section• Consists of a preselector and an amplifier• Preselector is a broad-tuned bandpass filter with an adjustable centerfrequency used to reject unwanted radio frequency (image frequency) and toreduce the noise bandwidth• RF amplifier determines the sensitivity of the receiver and a predominantfactor in determining the noise figure for the receiver2. Mixer/converter section• Consists of a radio-frequency oscillator and a mixer• Choice of oscillator depends on the stability and accuracy desired• Mixer is a nonlinear device to convert radio frequencies to intermediatefrequencies (I.e. heterodyning process)• The shape of the envelope, the bandwidth and the original informationcontained in the envelope remains unchanged although the carrier andsideband frequencies are translated from RF to IF3. IF section• Consists of a series of IF amplifiers and bandpass filters to achieve most of thereceiver gain and selectivity• The IF is always lower than the RF because it is easier and less expensive toconstruct high-gain, stable amplifiers for low-frequency signals.

• IF amplifiers are also less likely to oscillate than their RF counterparts4. Detector section• To convert the IF signals back to the original source information(demodulation)• Can be as simple as a single diode or as complex as a PLL or balanceddemodulator5. Audio amplifier section• Comprises several cascaded audio amplifiers and one or more speakers

C. Discuss Limiter, Discriminator and Zero Crossing detector of FM receiver.

C.

Explain Noise in Communication system in detail.

Q.4 A. Discuss Line Codes in detail.

B. Discuss Pulse Position Modulation in Detail with Block Diagram and Waveforms.

C. Explain Differential Pulse Code Modulation in detail.

D. Discuss Quantization Errors in Delta Modulation in detail.

D. Discuss FSK Modulation and Demodulation in Detail.

Q-1.A.1

Q-1.A.2