Abstract: The disclosed electronic processing apparatus calculates and applies calibrations to sensors that produce quasi-sinusoidal, quadrature signals. The apparatus includes either or both of fixed and programmable electronic circuits. The apparatus includes a circuit to calculate the phase and magnitude corresponding to the two input (quadrature) signals. The apparatus also includes a circuit for accumulating the number of cycles of the input signals. The apparatus also includes a circuit to generate Gain, Offset, and Phase calibration coefficients, wherein the circuit compares the phase space position of the measured phasor with the position of an idealized phasor, the locus of the idealized phasor in phase space being a circle of predetermined radius with no offset. The calculation of the coefficients occurs without user intervention, according to a pre-programmed rule or rules.

Abstract: A heterodyning lock-in amplifier in which the reference signal is shifted up in frequency (as in prior art designs), but then shifted back down in frequency prior to mixing with the input signal.

Abstract: Techniques for operating a power amplifier in driving a highly inductive load are provided. More particularly, the voltage across a coil load is integrated to obtain a signal representative of the flux and this signal is fed back as an error signal to the power amplifier to conform the instantaneous flux to the input voltage of the power amplifier. Since the power amplifier is operated in a voltage output mode and the flux is forced to conform to the input voltage, the effects of eddy currents are automatically compensated for while the power amplifier displays maximum bandwidth for pulse and sinusoidal input sequences.