MUST 1220 Lecture Notes - Lecture 7: Undersampling

• School: Northeastern University
• Department: Music Technology
• Course: MUST 1220
• Professor: Frengel Mike

Document Summary

Quantization is a procedure of constraining something from a continuous set of values (analog) to relatively small discrete set (digital). Digital audio signals are described by 2 measurements: sampling rate / sampling frequency, quantization (bit depth or word size) Sa(cid:373)pli(cid:374)g (cid:396)ate = (cid:374)u(cid:373)(cid:271)e(cid:396) of sa(cid:373)ples pe(cid:396) se(cid:272)o(cid:374)d. the (cid:373)o(cid:396)e ofte(cid:374) it"s sa(cid:373)pled, (cid:271)ette(cid:396) it is represented in discrete form. Sampling theorem (nyquist theorem) = to represent digitally a signal containing frequency components up to x hz, it is necessary to use a sampling rate of at least 2x hz. The max frequency contained in a signal sampled at rate of sr hz is sr/2 hz. Minimum sample rate required to capture audible frequency range of human hearing = 40 khz. Oversampled the audio frequency is below nyquist frequency. Critically sampled signal sampled at exactly the nyquist frequency. Runs risk of missing peaks and troughs and only sampling the zero crossing. Undersampling recording a frequency greater than nyquist frequency.