Digital Signal Processing Quiz

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Questions and Answers

What is the effect on the deviation d of an FM signal when it is passed through a mixer?

Reduces

Doubles

Remains unchanged (correct)

Becomes half

What is the output signal from a DSB-SC modulator?

PM signal

FM signal

Both FM and PM signal

Neither FM nor PM signal (correct)

What is the purpose of an amplitude limiter in FM receivers?

To remove amplitude variations due to noise (correct)

To amplify the FM signal

To filter out unwanted signals

To demodulate the FM signal

What is the modulation index of an FM wave given by s(t)=20cos(8π×106t+9sin(2π×103t))?

9 Signup and view all the answers

What is true about Frequency Modulation?

All of the above Signup and view all the answers

What does the amount of frequency deviation in FM signal depend on?

Amplitude of the modulating signal Signup and view all the answers

What is the modulation index of FM given by?

μ = frequency deviation/ modulating frequency Signup and view all the answers

What happens to the frequency deviation Δ when the modulating frequency is doubled?

Remains unchanged Signup and view all the answers

What is the result of the amplitude of the modulating signal being greater than the amplitude of the carrier?

Distortion Signup and view all the answers

What is the ratio of the modulating signal voltage to the carrier voltage called?

Modulation index Signup and view all the answers

What type of frequency modulation is generated using a VCO?

Indirect FM Signup and view all the answers

When does over-modulation occur in amplitude modulation?

Modulating signal voltage > Carrier voltage Signup and view all the answers

What is the modulating signal voltage if the maximum and minimum voltages on the wave are 10v and 5v respectively?

2.5v Signup and view all the answers

What is the circuit used for producing DSB-SC called?

Modulator Signup and view all the answers

What modulation technique is used to convert analog signal into digital signal?

Pulse code modulation Signup and view all the answers

What is the bandwidth of a carrier wave with a modulating frequency varying between 900kHz and 1100kHz?

200KHz Signup and view all the answers

What is the expression for bandwidth BW of a PCM system?

BW> = 2nfm Signup and view all the answers

Which of the following is an indirect form of frequency modulation?

Armstrong modulator Signup and view all the answers

What is the characteristic of a uniform quantizer in PCM?

The step size remains the same Signup and view all the answers

What is the maximum bandwidth of the message in a PCM system with a 7-bit binary encoder and a bit rate of 49*10^6bps?

7Mkbps Signup and view all the answers

In which type of modulation is the amplitude of the pulse train varied?

Pulse amplitude modulation Signup and view all the answers

What is the signal to quantization noise ratio for a signal with a highest frequency component of 3.2MHz and peak to peak value 6 volt, transmitted using PCM with 512 quantization levels?

36.98dB Signup and view all the answers

Study Notes

Modulation Techniques

Pulse Code Modulation (PCM) converts analog signal into digital signal
Other modulation techniques: AM modulation, FM modulation

Bandwidth of PCM System

Expression for bandwidth BW: BW > nfm, where n is the number of bits per sample and fm is the modulating frequency

Uniform Quantization

Step size remains same in uniform quantization process
The quantizer has linear characteristics

PCM System

Bit rate of the system is equal to 49*10^6bps
Maximum bandwidth of message: 7Mbps

Pulse Amplitude Modulation

Amplitude of the pulse train is varied in pulse amplitude modulation

Signal to Quantization Noise Ratio

For a signal with highest frequency component of 3.2MHz and peak to peak value 6 volt, signal to quantization noise ratio is 36.98dB

Amplitude Modulation

The ratio between the modulating signal voltage and the carrier voltage is called modulation index
Over-modulation occurs when the amplitude of the modulating signal is greater than the amplitude of the carrier

Voltage-Controlled Oscillator (VCO)

VCO is used to generate indirect FM

DSB-SC Modulator

The circuit used for producing DSB-SC is called a modulator

Frequency Modulation

The two types of angle modulation are phase and frequency modulation
Phase modulation is an indirect form of frequency modulation
The amount of frequency deviation is proportional to the amplitude of the intelligence signal in an FM signal

FM Signal

The effect on the deviation d of an FM signal when it is passed through a mixer: doubles
In Frequency Modulation, amplitude of the carrier remains same, frequency of the carrier varies in accordance with the modulating signal, and the number of side bands are infinite
The modulation index of FM is given by μ = frequency deviation/ modulating frequency
According to Carson’s rule, Bandwidth B and modulating frequency fm are related as B = 2(Δf + fm) Hz

Disadvantages of PCM

Encoding, decoding and quantizing circuitry of PCM is complex
PCM require large bandwidth as compared to the other systems

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Description

Test your knowledge of digital signal processing concepts, including modulation techniques, pulse code modulation, and quantization process.