Signals and Noises Questions and Answers for Viva

Answer-1: A signal is a function that conveys information about a phenomenon.

Answer-2: A signal is a pattern of variation in a physical quantity, such as voltage, current, or light intensity, that carries information from a source to a destination in a communication system.

Answer-3: There are two main type of signals: Analog signals and digital signals.

Answer-4: Common types of signals include analog signals, which vary continuously over time, and digital signals, which have discrete values representing binary data.

Answer-5: An analog signal is a continuous waveform that represents information by varying its voltage or frequency.

Answer-6: Noise refers to unwanted or random variations in a signal that interfere with the transmission or reception of information, typically resulting from external sources or imperfections in the communication system.

Answer-7: A digital signal is a discrete waveform that represents information using binary code (0s and 1s).

Answer-8: Main sources of noise include thermal noise (Johnson-Nyquist noise), which arises from the random motion of electrons in conductors, and intermodulation noise, which occurs when signals interact nonlinearly in amplifiers or other components.

Answer-9: Analog signals have infinite possible values within a range, while digital signals have discrete values (0 or 1).

Answer-10: Thermal noise adds random variations to the signal amplitude, leading to a degradation in signal-to-noise ratio (SNR) and potentially impacting the quality of communication systems, especially at low signal levels.

Answer-11: Modulation is the process of encoding information onto a carrier signal for transmission.

Answer-12: White noise is a type of noise that has a flat power spectral density across all frequencies, meaning it contains equal power per unit bandwidth. It differs from other types of noise, such as pink noise or Gaussian noise, which have different frequency characteristics.

Answer-13: Amplitude Modulation (AM) and Frequency Modulation (FM).

Answer-14: Noise introduces errors and distortions into the transmitted signal, reducing the accuracy and reliability of communication systems by making it more difficult to distinguish between the signal and unwanted variations.

Answer-15: The Nyquist theorem states that to accurately reconstruct a signal, the sampling rate must be at least twice the highest frequency component of the signal.

Answer-16: SNR is a measure of the relative strength of the desired signal compared to the level of background noise present in a communication system. A higher SNR indicates a cleaner and more reliable signal, which is essential for accurate data transmission and reception.

Answer-17: The Shannon-Hartley theorem provides a formula for calculating the maximum data rate (channel capacity) of a communication channel, considering the bandwidth and signal-to-noise ratio.

Answer-18: SNR is typically calculated as the ratio of the signal power to the noise power, often expressed in decibels (dB) using the formula SNR(dB) = 10 * log10(Signal Power / Noise Power).

Answer-19: Noise refers to unwanted random fluctuations or disturbances that interfere with the original signal.

Answer-20: Techniques to improve SNR include increasing the signal power, reducing noise sources through shielding or filtering, employing error correction coding, and using modulation schemes resilient to noise.

Answer-21: SNR is the ratio of the power of a signal to the power of background noise.

Answer-22: Signal processing involves the manipulation and analysis of signals to extract useful information or enhance signal quality. In communication systems, signal processing techniques such as filtering, equalization, and adaptive algorithms are used to reduce the impact of noise.

Answer-23: Signal processing involves manipulating signals to extract useful information or enhance their quality.

Answer-24: Multipath interference occurs when signals take multiple paths to reach the receiver, leading to signal reflections and phase shifts that can interfere with the original signal, causing distortion and reducing SNR.

Answer-25: Filtering is the process of removing or attenuating certain frequencies from a signal while preserving others.

Answer-26: Quantization noise arises from the process of approximating continuous amplitude values by discrete levels during analog-to-digital conversion. It contributes to the overall noise floor and can degrade signal quality, particularly in low-bit digital systems.

Answer-27: Fourier transform is a mathematical technique that decomposes a signal into its constituent frequencies.

Answer-28: Atmospheric noise, also known as cosmic noise or radio noise, originates from natural sources such as lightning discharges, solar radiation, and galactic noise. It can interfere with RF signals, especially at certain frequencies, reducing SNR and limiting communication range.

Answer-29: Sampling is the process of converting a continuous signal into a discrete signal by measuring its amplitude at regular intervals.

Answer-30: Techniques to mitigate noise in digital audio and video systems include dithering, noise shaping, error correction coding, and advanced digital signal processing algorithms for noise reduction and restoration.

Answer-31: Baseband signals have frequencies close to zero, while passband signals have frequencies that are shifted from zero.

Answer-32: Bandwidth influences the frequency range over which noise is distributed, with wider bandwidths potentially capturing more noise energy. Proper bandwidth management and filtering techniques are essential for minimizing noise in communication systems.

Answer-33: A demodulator extracts the original information from a modulated carrier signal.

Answer-34: Noise characteristics, including its frequency distribution, power level, and statistical properties, are considered during the design of communication channels and transmission systems to ensure adequate SNR and reliable data transmission under various operating conditions.

Answer-35: Bandwidth refers to the range of frequencies occupied by a signal and determines the data capacity of a communication channel.

Answer-36: Signal-to-noise ratio determines the quality of communication by indicating the level of signal strength relative to background noise.