Frequency counter
OwnerHendrik M. Wondergem, Robert J. Kaldenbachinventors
Life of this patent
Estimating the term…
Abstract
A frequency counter having particular utility for processing the output of proton precession magnetometers divides a signal to be counted into a large number of consecutive elements each of an integral number of half cycles, and counts the increment in total elapsed duration of the signal represented by each sample. The counts are stored, and the stored counts are then manipulated to provide a least squares approximation of their mean, and the standard deviation of that mean. The counter can provide enhanced accuracy, as well as an indication of the reliability of the readings obtained.
Claims13
Apparatus for determining the frequency of a cyclical component of a signal, comprising a signal source, filter means for receiving said signal and isolating said component, means for receiving said isolated component and dividing it at predetermined points in its cycle whereby to divide it into elements comprising an integral number of half cycles, an elapsed time counter means receiving said elements and outputting successive counts defining increments in total elapsed time corresponding to the successive elements, memory means receiving and storing said counts, a statistical calculator operative to receive said stored counts and provide an output proportional to a statistical means increment in total elapsed time, and read-out means operative to receive said output and provide a read-out of the frequency or period of said cyclical component of said signal, said statistical calculator being configured to determine a statistical mean increment such as to minimize the sum of the squares of the residuals of said successive total elapsed times as counted to the end of each element with respect to the corresponding incremental total elapsed times calculated on the basis of said mean.
A method of determining the frequency of a cyclical component of a signal, comprising isolating said cyclical component, dividing said component into elements corresponding in length to an integral number of half cycles of said component, measuring the increment in total elapsed duration of the signal represented by each of said elements, storing data determinative of said incremented total elapsed durations, and determining a least squares approximation of the mean increment in total elapsed duration.
A method of measuring a magnetic field strength, comprising operating a proton precession magnetometer to provide output signal bursts including a cyclical component due to proton precession, amplifying each such burst and isolating therefrom said component, dividing that part of the component in each burst, occuring after an initial settling period and prior to the strength of the component falling below a predetermined level, into elements comprising an integral number of half cycles, measuring the increment in total elapsed duration of the signal represented by each of said elements, storing data determinative of said incremented total elapsed durations, and determining a least squares approximation and standard deviation of the mean increment in total elapsed duration.
Dependencies are inferred from the claim text.