Method and apparatus for sampling broad band spectra in fuel quantity measurement systems

A method for determing sampling frequencies of a broad band sparse spectrum .PHI. having a base band, a carrier frequency f.sub.c and a sampling frequency f.sub.s, comprising the steps of,

• (i) determing the number of bands in said spectrum containing significant levels of energy,
• (ii) determining the bandwidths of each of said bands, and
• (iii) arranging for said number of bands unacceptable values of the remainder of the quotient of f.sub.c /f.sub.s into a series in order of magnitude,
• (iv) selecting those sampling frequencies which cause adjacent forbidden ranges of said remainder to become contiguous in said spectrum,
• (v) selecting a given value of said sampling frequencies, and
• (vi) obtaining a related sampling interval for said given value for said spectrum without aliasing to said base band.

An apparatus for sampling a broad band sparse signal spectrum having a base band and a carrier frequency, comprising,

• a liquid level sensing means for generating said signal spectrum,
• selection means for determining the number of bands in said spectrum containing significant levels of energy,
• means for measuring the bandwidths of each of said bands, and
• means for sampling the frequency of said bands, whereby all the integer multiples of said frequency lie in a region of said spectrum where there is no energy to be aliased.