Principles of Communication Systems Quiz & Flashcards

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Define the standard form of amplitude modulation and derive its equation. Explain each term.

The standard form of amplitude modulation is given by the equation: $s(t) = A_c [1 + m(t)] imes ext{cos}(2 ext{π}f_ct)$, where $A_c$ is the carrier amplitude, $m(t)$ is the message signal, and $f_c$ is the carrier frequency. The term $A_c$ represents the carrier amplitude, $m(t)$ represents the message signal, and $f_c$ represents the carrier frequency.

Explain the generation of DSBSC waves using a Ring Modulator.

DSBSC waves are generated using a Ring Modulator by multiplying the message signal by the carrier signal, resulting in the suppression of the carrier and generation of double sidebands.

What will be the frequency content of the AM signal when a 1000 KHz carrier is simultaneously modulated to 300 Hz, 800Hz, and 2KHz audio Sinewaves?

The frequency content of the AM signal will include the carrier frequency at 1000 KHz, the upper sideband frequencies at 1000.3 KHz, 1000.8 KHz, and 1002 KHz, and the lower sideband frequencies at 999.7 KHz, 999.2 KHz, and 998 KHz.

Explain the scheme of generation and demodulation of VSB modulated wave with relevant spectrum of signals and mathematical expressions.

The VSB modulated wave is generated by suppressing one sideband and transmitting the other along with the carrier. It is demodulated by using a coherent carrier and a synchronous detector. The spectrum of VSB signals includes the carrier and a single sideband, with the other sideband suppressed. Signup and view all the answers

Calculate the sidebands of DSBSC modulated waves appearing at the two product modulator outputs in a two-stage product modulator with given input signal and local oscillator frequencies.

i) The sidebands of DSBSC modulated waves appearing at the two product modulator outputs are at 99.7 KHz and 100.3 KHz. ii) The pass-bands of the two BPF’s are 0 to 200 KHz and 9.8 to 10.2 MHz. Signup and view all the answers

Explain the working of a FDM transmitter and receiver with a neat block diagram.

The FDM transmitter combines multiple signals onto a single channel by modulating each signal with a unique carrier frequency. At the receiver, the signals are demodulated and separated using filters. Signup and view all the answers

Find the carrier, modulating frequency, modulation index, and maximum frequency deviation of the given FM wave represented by the voltage equation.

Carrier frequency: 6 × 10^8 Hz, Modulating frequency: 1250 Hz, Modulation index: 5, Maximum frequency deviation: 75 kHz Signup and view all the answers

Derive the expression for WBFM and show that the spectrum of WBFM wave contains an infinite number of sidebands.

The expression for WBFM is given by the modulation index equation. The spectrum of WBFM contains an infinite number of sidebands due to the Bessel function expansion. Signup and view all the answers

Determine the bandwidth of an FM signal with a fixed maximum frequency deviation and modulation frequency using Carson’s rule and the universal curve.

i. By Carson’s rule: 150 kHz, ii. By universal curve: 240 kHz Signup and view all the answers

Explain the direct method generation of FM using Hartley Oscillator with relevant equations and diagram.

The direct method of FM generation using Hartley Oscillator involves modulating the frequency of the oscillator based on the input signal. This can be explained using the relevant frequency modulation equation and a diagram of the Hartley Oscillator. Signup and view all the answers

Write the basic block diagram of PLL and derive the expression for the nonlinear model of PLL.

The basic block diagram of PLL includes a phase detector, a loop filter, and a voltage-controlled oscillator (VCO). The nonlinear model of PLL can be derived by considering the phase detector and the characteristics of the VCO. Signup and view all the answers

Derive the expression for the Figure of Merit of a frequency modulated receiver.

The Figure of Merit for an FM receiver can be derived using the equation involving the signal-to-noise ratio and the minimum detectable signal. Signup and view all the answers

Define noise and explain Noise Equivalent Bandwidth with relevant equations.

Noise is random unwanted signals that interfere with the communication of information. Noise Equivalent Bandwidth is a measure of the effective noise bandwidth of a system, and it can be calculated using relevant equations. Signup and view all the answers

Using the expression for the figure of merit of AM, find the FOM of single tone AM.

The FOM of single tone AM can be calculated using the equation involving the modulation index and the signal-to-noise ratio. Signup and view all the answers

Explain the generation and detection of PPM waves with neat block diagrams.

The generation of PPM waves involves sampling the input signal and producing pulses based on the sampled values. The detection process includes demodulation and reconstruction of the original signal. Signup and view all the answers

Explain the generation and recovery of PAM (Flat-top) signal with necessary equations and spectrum diagram.

The generation of PAM (Flat-top) involves sampling and quantization of the input signal, followed by the creation of flat-topped pulses. The recovery process includes low-pass filtering to reconstruct the original signal. Signup and view all the answers

Describe the effect of Noise on a Pulse position modulation System.

Noise in a PPM system can lead to errors in pulse detection and timing, affecting the accuracy of information transmission. Signup and view all the answers

State the Sampling theorem and explain the necessity of Digitizing of analog signals.

The Sampling theorem states that a continuous signal can be accurately represented by discrete samples if the sampling frequency is at least twice the signal's maximum frequency. Digitizing analog signals is necessary to enable processing, storage, and transmission of the signals using digital systems. Signup and view all the answers

Explain the effect of Noise on a Pulse position modulation System.

Noise in a Pulse Position Modulation (PPM) system can cause errors in pulse detection, leading to inaccuracies in the transmission of information. Signup and view all the answers

Derive the expression for the output Signal to Noise Ratio of a Quantizer.

The output Signal to Noise Ratio of a Quantizer can be derived using the equation involving the quantization error and the power of the input signal. Signup and view all the answers

Explain the basic elements of a PCM system with a neat diagram.

A PCM system consists of a sampler, quantizer, encoder, transmission channel, decoder, and reconstruction filter. These elements work together to digitize, transmit, and reconstruct analog signals. Signup and view all the answers

Calculate the Nyquist rate, number of bits required to encode a sample, and the quantization step for a given PCM system scenario.

a. Nyquist rate: 30 kHz, b. Number of bits required: 16 bits, c. Quantization step: 0.0000305 volts Signup and view all the answers

Flashcards

Amplitude Modulation (AM)

A form of modulation where the amplitude of the carrier wave is varied in proportion to that of the message signal.

Modulation Index (μ)

A factor in AM representing the amount of amplitude variation around its unmodulated value.

DSBSC Modulation

AM technique where the carrier wave is suppressed, transmitting only sidebands.

Ring Modulator

Electronic circuit used to generate DSBSC signals by multiplying the carrier wave with the modulating signal.