Analog and Digital Signal Processing Questions and Answers for Viva

Answer-1: Demodulation is the process of extracting the original information signal from a modulated carrier signal at the receiver end of a communication system.

Answer-2: Noise refers to unwanted random variations or disturbances that interfere with the transmission or processing of signals, reducing the quality of the signal.

Answer-3: Digital signal processing is used in various applications, including audio and video processing, telecommunications, medical imaging, radar, sonar, and control systems.

Answer-4: Signal processing involves manipulating signals to extract useful information or enhance specific characteristics.

Answer-5: An analog signal is a continuous signal that varies smoothly over time, represented by a continuous waveform.

Answer-6: A digital signal is a discrete-time signal that is represented using a finite set of discrete values, typically binary numbers.

Answer-7: Analog signal processing deals with continuous signals, while digital signal processing (DSP) involves processing discrete-time signals represented by sequences of numbers.

Answer-8: Converting analog signals into digital form is useful for communication systems because it enables noise reduction, efficient data storage, and easy manipulation through digital processing techniques. Additionally, digital signals can be transmitted over long distances with minimal loss of quality due to error detection and correction mechanisms.

Answer-9: Analog-to-digital conversion (ADC) transforms continuous analog signals into discrete digital values. The process involves three main steps: sampling, quantization, and encoding.

Answer-10: Periodically measuring the amplitude of the analog signal at uniform intervals, called the sampling rate. Nyquist-Shannon theorem states that the sampling rate must be at least twice the highest frequency component in the signal to avoid aliasing.

Answer-11: Approximating sampled amplitudes by assigning them to a finite set of discrete levels, known as quantization levels. This introduces quantization error, which can be reduced by increasing the number of levels or using better algorithms like dithering.

Answer-12: Representing each quantized level with a unique binary code, typically using fixed-length binary numbers. The number of bits used determines the resolution of the ADC, with more bits providing higher accuracy and dynamic range.

Answer-13: PCM (Pulse Code Modulation) is a method that samples analog signals at regular intervals and quantizes them into discrete digital values. Advantages include high fidelity, low noise, and ease of processing. Disadvantages are large bandwidth requirements and susceptibility to quantization errors.

Answer-14: DPCM (Differential Pulse Code Modulation) encodes the difference between consecutive samples instead of absolute values. This reduces redundancy and data size. Advantages include lower bandwidth requirements and better compression ratios. Disadvantages involve increased complexity and potential error propagation.

Answer-15: DM (Delta Modulation) is a simpler version of DPCM, encoding only the sign of the difference between consecutive samples. Advantages include simplicity, low computational complexity, and reduced bandwidth requirements. Disadvantages consist of poor performance in rapidly changing signals and higher noise levels.

Answer-16: Filters play a crucial role in signal processing by selectively allowing specific frequency components to pass through while attenuating others. They help eliminate noise, extract useful information, and shape the overall characteristics of signals.

Answer-17: Low-pass filters allow frequencies below a certain cutoff point to pass through, effectively removing high-frequency noise or preserving low-frequency content. Applications include audio equalization, anti-aliasing, and smoothing data.

Answer-18: High-pass filters permit frequencies above a specified threshold, eliminating low-frequency noise or retaining high-frequency details. Uses involve edge detection in image processing, DC offset removal, and enhancing speech clarity.

Answer-19: Band-pass filters transmit a particular range of frequencies, rejecting those outside this band. They are employed for isolating desired frequency bands in communication systems, tuning radio stations, and analyzing specific frequency components in signals.

Answer-20: Band-stop filters, conversely, block a designated frequency range while passing all others. These filters find use in eliminating interference from known sources, such as power line hum in audio recordings or suppressing undesired frequency bands in telecommunication systems.

Answer-21: Finite Impulse Response (FIR) filters have a finite impulse response, meaning their output depends only on past input values. In contrast, Infinite Impulse Response (IIR) filters have feedback, causing their output to depend on both past input and output values.

Answer-22: Signal modulation is the process of encoding information onto a carrier signal by varying its amplitude, frequency, or phase, used in telecommunications and broadcasting.

Answer-23: Digital modulation involves modifying the characteristics of a carrier signal to represent digital data, enabling efficient transmission and reception of digital information.