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Noise in communication systems is generally divided into two categories. Which of the following correctly represents those categories?
Noise in communication systems is generally divided into two categories. Which of the following correctly represents those categories?
What type of noise is often called static noise?
What type of noise is often called static noise?
Lightning is a physical source of what type of noise?
Lightning is a physical source of what type of noise?
Which type of noise can be a serious problem for satellite reception?
Which type of noise can be a serious problem for satellite reception?
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What type of noise is sometimes called white noise?
What type of noise is sometimes called white noise?
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What is the formula for calculating the equivalent noise temperature of two resistors in series, given their respective resistances (R₁ and R₂) and temperatures (T₁ and T₂)?
What is the formula for calculating the equivalent noise temperature of two resistors in series, given their respective resistances (R₁ and R₂) and temperatures (T₁ and T₂)?
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The equivalent noise temperature of a parallel combination of two resistors with the same resistance (R), operating at noise temperatures T₁ and T₂, respectively, is:
The equivalent noise temperature of a parallel combination of two resistors with the same resistance (R), operating at noise temperatures T₁ and T₂, respectively, is:
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What type of noise is mainly due to the random drift of current carriers across junctions?
What type of noise is mainly due to the random drift of current carriers across junctions?
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What does the term "ensemble" refer to in the context of noise analysis?
What does the term "ensemble" refer to in the context of noise analysis?
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A process whose future value can be predicted based on its past values is called?
A process whose future value can be predicted based on its past values is called?
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What does noise figure represent in a communication system?
What does noise figure represent in a communication system?
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What does Friss's formula help determine?
What does Friss's formula help determine?
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What is the formula for calculating channel capacity (C) in an additive white Gaussian noise (AWGN) channel, given Bandwidth (B) and signal-to-noise ratio (S/N)?
What is the formula for calculating channel capacity (C) in an additive white Gaussian noise (AWGN) channel, given Bandwidth (B) and signal-to-noise ratio (S/N)?
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What does the Shannon-Hartley theorem tell us in Information Theory?
What does the Shannon-Hartley theorem tell us in Information Theory?
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Which of the following is NOT a use case for Huffman coding?
Which of the following is NOT a use case for Huffman coding?
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The Shannon-Fano coding algorithm is an entropy encoding technique for ____ data compression.
The Shannon-Fano coding algorithm is an entropy encoding technique for ____ data compression.
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What is the primary purpose of the Shannon-Fano algorithm?
What is the primary purpose of the Shannon-Fano algorithm?
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The splitting process in the Shannon-Fano coding is stopped when each symbol is separated into its own group.
The splitting process in the Shannon-Fano coding is stopped when each symbol is separated into its own group.
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Which of the following correctly describes the Shannon-Fano coding algorithm?
Which of the following correctly describes the Shannon-Fano coding algorithm?
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The information capacity theorem in communication theory defines the ______.
The information capacity theorem in communication theory defines the ______.
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What is the formula for determining the equivalent noise temperature (Te) of cascaded two-port networks, given the noise temperature (Te1 and Te2) of each network and the gain (g₁₁) of the first network?
What is the formula for determining the equivalent noise temperature (Te) of cascaded two-port networks, given the noise temperature (Te1 and Te2) of each network and the gain (g₁₁) of the first network?
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Which of these is NOT a primary source of external noise?
Which of these is NOT a primary source of external noise?
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The noise figure of a circuit can be thought of as a measure of its signal-to-noise ratio, with lower noise figures indicating better performance.
The noise figure of a circuit can be thought of as a measure of its signal-to-noise ratio, with lower noise figures indicating better performance.
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Thermal noise is also known as _________
Thermal noise is also known as _________
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Which of the following is NOT a type of internal noise?
Which of the following is NOT a type of internal noise?
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What is the formula for calculating the power of thermal noise?
What is the formula for calculating the power of thermal noise?
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What does the term "autocorrelation" refer to in signal processing?
What does the term "autocorrelation" refer to in signal processing?
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The concept of information entropy was introduced by Claude Shannon and is defined as the average level of information, surprise, or uncertainty inherent in a random variable.
The concept of information entropy was introduced by Claude Shannon and is defined as the average level of information, surprise, or uncertainty inherent in a random variable.
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Which of these is NOT a key element of a data communication system as defined by Shannon's theory?
Which of these is NOT a key element of a data communication system as defined by Shannon's theory?
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The fundamental problem of communication, as described by Shannon, involves the receiver identifying the data generated by the source based on the received signal.
The fundamental problem of communication, as described by Shannon, involves the receiver identifying the data generated by the source based on the received signal.
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Shannon's source coding theorem proved that the entropy of a random variable represents an upper limit on the efficiency of lossless data compression.
Shannon's source coding theorem proved that the entropy of a random variable represents an upper limit on the efficiency of lossless data compression.
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Shannon's noisy-channel coding theorem demonstrates that error-free communication can be achieved over noisy channels, but only if the information rate is below the channel capacity.
Shannon's noisy-channel coding theorem demonstrates that error-free communication can be achieved over noisy channels, but only if the information rate is below the channel capacity.
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In a communication system, the information value of a message depends on how surprising the content of the message is.
In a communication system, the information value of a message depends on how surprising the content of the message is.
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Which of the following statements correctly reflects the concept of surprisal in information theory?
Which of the following statements correctly reflects the concept of surprisal in information theory?
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What does the term "data compression" refer to?
What does the term "data compression" refer to?
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Which type of data compression removes unnecessary information, potentially resulting in some quality loss?
Which type of data compression removes unnecessary information, potentially resulting in some quality loss?
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Huffman coding is a type of lossless data compression and is a component of many standard video compression formats like MPEG.
Huffman coding is a type of lossless data compression and is a component of many standard video compression formats like MPEG.
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What is the main purpose of Shannon-Fano coding?
What is the main purpose of Shannon-Fano coding?
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Which of these is NOT a step involved in the Shannon-Fano coding algorithm?
Which of these is NOT a step involved in the Shannon-Fano coding algorithm?
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The Shannon-Fano codes are considered accurate if each symbol gets a unique code.
The Shannon-Fano codes are considered accurate if each symbol gets a unique code.
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Study Notes
Noise in Signals
- Noise is defined as an unwanted electrical signal that accompanies a desired signal in transmission.
- Noise disrupts the transmission and reproduction of signals.
- Many electrical disturbances create noise in communication systems.
- Noise can be predictable or unpredictable (random noise).
- Predictable noise has known values and can be easily eliminated.
- Random noise is eliminated or minimized by analyzing its statistical behavior.
- Noise increases system complexity.
- Noise is present across all frequencies.
Types of Noise
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External noise originates outside the receiver/system.
- Atmospheric noise: arises from lightning discharges and other natural electric disturbances in the atmosphere.
- Extraterrestrial noise: generated by the sun (solar noise) and other celestial bodies (cosmic noise).
- Industrial noise: created by electrical disturbances from industries, automobiles, aircraft, and various equipment.
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Internal noise: originates within the device or system.
- Shot noise: fluctuation in the anode current of vacuum tubes, due to the random emission of electrons from a cathode.
- Flicker noise: proportional to the emitter current and junction temperature, inversely proportional to frequency.
- Transit time noise: observed at high frequencies when the time taken by electrons to travel from the emitter to the collector in a transistor becomes significant.
- Thermal noise (also known as Johnson noise or Nyquist noise): caused by random thermal motion of electrons in a conductor.
Effects of Noise
- Noise can generate unwanted signals or cancel desired values in communication systems.
- Noise leads to significant mathematical errors in computations.
- Noise limits the range of systems for a given transmitted power.
- Noise reduces the sensitivity of receivers and bandwidth of the system.
Noise Classification
- Noise can be classified based on its source:
- External noise
- Internal noise
Equivalent Noise Bandwidth
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The equivalent noise bandwidth (BN) of a system is the bandwidth of an ideal system that produces the same output power as the actual system with infinite bandwidth.
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BN = ∫0∞ |H(ω)|2 dω / |H(ω0)|2
Equivalent Noise Temperature
- Equivalent noise temperature (Te) is used to describe noise in a passive RLC network or an active device.
- Te = P/kB for passive systems, where P is the available noise power and kB is Boltzmann's constant.
- For active devices, the equivalent noise temperature is equivalent to an increase in noise density.
Noise Figure
- Noise figure (F) is used to evaluate the noise performance of a system.
- F = (Total output noise power) / (noise power due to input noise source)
- Value of F > 1 indicates a noisy system.
Noise in Cascade Amplifiers
- The overall gain of a system of cascaded amplifiers is the product of the individual amplification stages.
- The overall noise figure of cascaded amplifiers is the sum of the individual noise figures.
- The overall noise figure equation is also calculated based on the gain of each amplifier stage.
Information Capacity
- Shannon's information theory defines the amount of information in a random variable as entropy or surprise level.
- Shannon's theory identifies three primary components of communication systems: a source of data, a communication channel, and a receiver.
- The fundamental problem in communication is to transmit data in a way that the receiver accurately recreates the original signal sent by the source.
- Shannon demonstrates that bandwidth, signal to noise ratio, and the rate of information transmission are crucial parameters in the design of efficient communication systems.
- The channel capacity is the maximum rate at which information can be transmitted over the communications channel.
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Description
This quiz explores the concept of noise in signal transmission, detailing its impact on communication systems. It covers various types of noise, including external and internal sources, and how they affect signal clarity. Test your understanding of noise characteristics and management techniques.
