sub-Nyquist sampling

(communications) Any technique of sampling an analog signal at a rate lower than the Nyquist rate in such a way as to preserve signal content without aliasing distortion. In particular, the sampling of television signals at a rate lower than the Nyquist rate and at an odd multiple of the frame rate, so that the aliasing components are placed into periodically spaced voids in the television spectrum where they can be removed by a comb filter at the receiver.