Types of Noise and Signal Distortion Quiz

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Questions and Answers

What is the purpose of quantization in the sampling process?

To represent digital data in waveform format

To convert analog signals to their digital form

To enhance the quality of the transmission medium

To approximate the amplitude of a pulse to the nearest permitted integer (correct)

Which modulation technique is associated with converting analog amplitudes to discrete levels?

Pulse Amplitude Modulation (PAM) (correct)

Frequency Modulation (FM)

Amplitude Modulation (AM)

Pulse Code Modulation (PCM)

What defines attenuation in communication signals?

The increase in signal strength with distance

The conversion of digital signals into binary code

The introduction of unwanted signals into a desired signal

The decrease in signal strength as it travels along a transmission medium (correct)

Which type of noise is caused by natural atmospheric phenomena?

Atmospheric noise Signup and view all the answers

What process converts discrete signals into highs (1) and lows (0)?

Pulse Code Modulation (PCM) Signup and view all the answers

What is the frequency of violet light with a wavelength of 400 nm?

7.5 × 10^14 Hz Signup and view all the answers

What does the term 'modem' refer to?

Modulator and demodulator Signup and view all the answers

What is the primary source of solar noise?

The sun Signup and view all the answers

In amplitude modulation (AM), which aspect of the carrier signal varies?

Carrier amplitude Signup and view all the answers

What causes thermal noise in electrical conductors?

Thermal agitation of charges Signup and view all the answers

If a sampling signal has a frequency of 50 Hz, what is its period?

0.02 sec Signup and view all the answers

Which modulation technique involves varying the frequency of the carrier?

Frequency modulation (FM) Signup and view all the answers

Which type of noise is particularly noticeable in semiconductor devices?

Shot noise Signup and view all the answers

What does distortion refer to in data transmission?

The alteration of the signal's form Signup and view all the answers

What does modulation do to a data signal?

Adds information to an electronic carrier signal Signup and view all the answers

How is the signal-to-noise ratio (S/N ratio) quantitatively described?

The ratio of signal power to noise power Signup and view all the answers

What is the relationship between frequency and wavelength in a wave equation?

Inversely proportional Signup and view all the answers

In the formula $S/N ratio = 10 log_{10} (P_s / P_n)$, what does $P_s$ represent?

Signal power Signup and view all the answers

When converting an analog signal to a digital signal, what process is commonly used?

Pulse Amplitude Modulation (PAM) Signup and view all the answers

What is the S/N ratio when a signal of 2.5 volts rms is corrupted by 10 mV rms of noise?

48 dB Signup and view all the answers

What is the S/N ratio of a signal with 350 watts transmitted through a cable medium with 60 watts of noise?

7.66 dB Signup and view all the answers

What is the main difference between analog and digital signals?

Analog signals have an infinite number of values, while digital signals are binary. Signup and view all the answers

Which formula correctly represents the relationship between wavelength, wave speed, and frequency?

$𝜆 = rac{c}{𝑓}$ Signup and view all the answers

How is frequency expressed in terms of measurement?

Cycles per second Signup and view all the answers

What describes a periodic signal?

It has a cycle that repeats over time. Signup and view all the answers

How is amplitude defined in terms of a wave?

The height of the crest from the equilibrium point. Signup and view all the answers

If a signal has a period of 0.00235 seconds, how is its frequency calculated?

$f = rac{1}{0.00235}$ Signup and view all the answers

Which of the following is NOT true about nonperiodic signals?

They always consist of discrete values. Signup and view all the answers

What is the unit for measuring frequency?

Hertz Signup and view all the answers

Study Notes

Types of Noise in Signals

Solar Noise: Originates from the sun.
Cosmic Noise: Generated by distant stars.
Thermal Noise: Results from thermal agitation of charges in electrical conductors.
Shot Noise: Caused by fluctuations in electrical current, noticeable in semiconductor devices.

Signal Distortion

Distortion: Refers to the alteration of a signal during data transmission.
Delay Distortion: A phenomenon in guided transmission media where different signal frequencies travel at different speeds.

Signal-to-Noise Ratio (SNR)

Definition: A quantitative measure of signal quality, representing the ratio of signal power to noise power.
Formula:
- ( \text{S/N ratio} = 10 \log_{10} \left( \frac{P_s}{P_n} \right) ) in dB
- ( \text{S/N ratio} = 20 \log_{10} \left( \frac{V_s}{V_n} \right) ) in dB
Example Calculations:
- For a 2.5 volts rms signal with 10 mV noise: SNR = 48 dB.
- For a 350 watts signal with 60 watts noise: SNR = 7.66 dB.

Types of Signals

Analog Signals: Continuous values, represented by a sine wave, e.g., speech and audio.
Digital Signals: Binary values (0 and 1), represented by a square wave, having discrete levels.
Periodic Signals: Repeated patterns within measurable time frames, called cycles.
Nonperiodic Signals: Random changes without a repeating pattern.

Signal Properties

Wavelength (( \lambda )): Related to frequency; ( \lambda = \frac{c}{f} ) where ( c ) is the speed of light.
Frequency (( f )): Number of waves passing a point each second; ( f = \frac{1}{T} ) where ( T ) is the period.
Amplitude: Height of the wave, measured from equilibrium to peak or trough.

Modems

Definition: A combination of "modulator" and "demodulator" for converting digital data into a signal compatible with transmission media.
Modulation Types:
- Amplitude Modulation (AM): Varies carrier amplitude based on the information signal.
- Frequency Modulation (FM): Varies carrier frequency based on the information signal.
- Phase Modulation (PM): Varies carrier phase based on the information signal.

Analog-to-Digital Conversion

Sampling: Converts analog signals into discrete levels via ADC.
Pulse Amplitude Modulation (PAM): Initial step in converting analog signals.
Quantization: Approximates amplitude values of pulses to the nearest integer.
Pulse Code Modulation (PCM): Represents discrete signals as binary equivalents.

Channel Impairments

Attenuation: Decrease in signal strength with distance traveled along the medium.
Noise: Unwanted signals superimposed onto desired signals.
- Atmospheric Noise: Arises from natural phenomena (e.g., lightning).
- Man-made Noise: Generated by human activities and electrical equipment.
- Extraterrestrial Noise: Includes solar and cosmic noise, originating from outside Earth.

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Description

Test your knowledge on various types of noise in signals, including solar, cosmic, thermal, and shot noise. Additionally, explore concepts of signal distortion, and the critical signal-to-noise ratio (SNR) calculations that affect signal quality. This quiz is essential for students studying communication systems and signal processing.