Frequency measurement procedures for a periodic signal as well as a frequency measuring device to perform this procedure.

摘要

Frequency measurement involves anti-foldover filtering (1) of an analog signal whose frequency i.e. to be measured, followed by sampling of the filtered analog signal and analog-digital conversion of the samples, then digital band-pass filtering (3) on a slaved basis. Associated calculation (4-7) utilizes a linear regression having a single coefficient a for the linear relation between successive digitized samples (2) and to estimate the coefficient a for approximation of the frequency to be measured. The invention is particularly applicable to signals from a probe having nuclear magnetic resonance used in measuring intensity of the terrestrial magnetic field disturbed by metallic masses.