Electronic measurement instrument probe accessory offset, gain, and linearity correction method
AssigneeTektronix, Inc.
InventorClifford E. Baker
Life of this patent
Estimating the term…
Abstract
A correction method for an electronic instrument accessory probe utilizes an error correction equation wherein at least one term contains an exponent less than unity. One simple such equation is: S=Cs2+Bs+A+b|s|x (where 0<x<1), but additional terms may be added, either with integer exponents greater than 2, or with other fractional exponents less than one. In the most simple embodiment, there are only four coefficients and the only term with a fractional exponent has an exponent of ½ (i.e., x=0.5). A second set of coefficients may be needed for the correction of negative values.
Claims16
A method for compensating for offset, gain, and linearity errors in a measured signal, s, sent from an probe accessory to an electronic measurement instrument via a conductive pathway, said probe accessory serving the function of monitoring one or more of electrical parameter such as voltage, current, impedance, or frequency, said measured signal communicating an uncorrected indication of the monitored electrical parameter's values, the method producing an error corrected signal, S, having reduced offset, gain, and linearity errors over a predetermined range of calibrated values, the method comprising the steps of:
- calibrating the probe accessory and conductive pathway with respect to a particular one of the electrical parameters to find four or more coefficients for a correction function having the form:
- S=Cs2+Bs+A+b|s|x, where 0<x<1 and further coefficients beyond four are associated with either higher powers of s, such as Ds3, or additional terms with different values of x still satisfying the condition 0<x<1, such as c|s|x′, such that when the correction function is applied to the communicated signal, s, for values within the predetermined range of calibrated values, an enhanced accuracy signal, S, is produced;
- monitoring one of the electrical parameters with the probe accessory and communicating the values of the measured signal s over the conductive pathway to the electrical measurement instrument, the values of the measured signal s being within the predetermined range of calibrated values;
- and
- applying the correction function using the predetermined four or more coefficients to the values of the measured signal s, thereby producing values of S.
Dependencies are inferred from the claim text.