Nedsampling

nedsampling is the process of reducing the sampling rate of a discrete-time signal by a factor M. In English, the term decimation is often used, and the process is a common operation in multi-rate digital signal processing. Conceptually, nedsampling keeps only every M-th sample from the original sequence, producing a signal with a lower sample rate.

Without prior filtering, nedsampling can cause aliasing, the folding of high-frequency components into lower frequencies. To prevent this, a low-pass (anti-aliasing) filter is typically applied before decimation, with a passband up to the new Nyquist frequency (original Nyquist frequency divided by M). After filtering, every M-th sample is kept.

Methods include simple decimation and more advanced polyphase implementations, which efficiently combine filtering and downsampling. The choice of filter (FIR or IIR) and its order affects passband ripple, stopband attenuation, delay, and computation.

Applications span audio, image and video processing, sensor data reduction, telecommunication, and real-time systems. Downsampling can reduce data rate for storage or transmission, but risks loss of information and perceptual artifacts if not performed with appropriate filtering and rate choice.