Digital Filters Design Questions and Answers for Viva

Answer-1: A digital filter is a system that processes digital signals to modify or improve their characteristics.

Answer-2: Finite Impulse Response (FIR) filters and Infinite Impulse Response (IIR) filters.

Answer-3: FIR filters have a finite impulse response, meaning their output is a weighted sum of the input samples. IIR filters have an infinite impulse response due to feedback, which makes them recursive.

Answer-4: FIR filters offer linear phase response, stability, and ease of design.

Answer-5: Digital filters can be designed using various methods, including windowing, frequency sampling, and optimization techniques like least squares or Parks-McClellan algorithm.

Answer-6: The impulse response of a filter is its output when the input is an impulse signal, which is a single sample followed by zeros.

Answer-7: The passband is the range of frequencies that the filter allows to pass with minimal attenuation, while the stopband is the range of frequencies that the filter attenuates heavily.

Answer-8: Filter order determines the complexity of the filter. Higher-order filters can achieve sharper frequency responses but require more computational resources.

Answer-9: Cutoff frequency is the frequency at which the filter begins to attenuate the signal. For low-pass and high-pass filters, it separates the passband from the stopband.

Answer-10: Filter design specifications define the desired characteristics of the filter, such as cutoff frequencies, passband ripple, and stopband attenuation.

Answer-11: Aliasing occurs when high-frequency components of the signal fold back into the passband due to improper sampling or inadequate filtering.

Answer-12: The Chebyshev filter is a type of filter with a passband ripple that is optimized for a specific trade-off between passband ripple and stopband attenuation.

Answer-13: The Butterworth filter has a maximally flat frequency response in the passband and is commonly used in applications where a flat frequency response is desired.

Answer-14: The Gibbs phenomenon refers to the oscillations that occur near the edges of a signal when it is filtered using a finite-length filter, such as a windowed FIR filter.

Answer-15: Group delay is the time delay experienced by each frequency component of the signal as it passes through the filter. It is a measure of the phase distortion introduced by the filter.

Answer-16: Linear phase filters have a constant group delay across all frequencies, while nonlinear phase filters exhibit varying group delay.

Answer-17: A high-pass filter attenuates low-frequency components of the signal while allowing high-frequency components to pass through.

Answer-18: The frequency response of a filter is typically represented using magnitude and phase plots, showing how the filter affects the amplitude and phase of each frequency component of the signal.

Answer-19: A stable filter produces a bounded output for any bounded input, ensuring that the filter does not introduce instabilities or oscillations.

Answer-20: Digital filters are used in a wide range of applications, including audio processing, image processing, telecommunications, biomedical signal processing, and control systems.