Measuring system for comparing the relative magnitudes of first and second d.c. signals

Claim 2

A measuring system for comparing the relative magnitudes of a first and a second D.C. input signal, said system comprising: means for symmetrically integrating said first signal between time period intervals proportional to its magnitude relative to the magnitude of said second signal; switching means for periodically reinitiating said symmetrical integrating cycle; and pulse generating means responsive to the half-period cycles of said symmetrical integrating means so that output pulses are generated at a frequency which is a multiple of said integrating cycle.

Claim 3

The measuring system of claim 1 wherein said symmetrical integrating means includes a pair of substantially matched operational amplifiers each having a pair of oppositely poled input terminals and an output terminal, said amplifiers having one set of like poled input terminals connected in common and the other set of like poled input terminals coupled to said first input signal, said first amplifier having twice the gain of said second amplifier and said second amplifier including a feedback capacitor for integral action connected between its output terminal and its said input terminal coupled to said first input signal, said first amplifier having its output terminal coupled to the feedback input terminal of said second amplifier through said switching means so that the output signal at the output terminal of said second amplifier has a substantially triangular wave form with a half-wave periodicity directly proportional to the ratio of said second input signal and said first input signal.

Claim 4

The measuring system of claim 2 wherein said switching means includes means for comparing the output signal from said second amplifier with both said second input signal and with a ground reference potential, said comparing means providing a first pulSe output whenever the output signal from said second amplifier is substantially equal to said second input signal and providing a second pulse output whenever the output signal from said second amplifier is substantially equal to said ground reference potential.

Claim 5

The measuring system of claim 3 wherein said switching means further includes flip-flop means for controlling the application of the output signal of said first amplifier to the feedback input terminal of said second amplifier, said flip-flop means being responsive to said first pulse output of said comparing means to apply the output signal of said first amplifier until said flip-flop means is reset in response to said second pulse output of said comparing means.

Claim 6

The measuring system of claim 3 wherein said pulse generating means responsive to the half-period cycles of said symmetrical integrating means includes flip-flop means for responding to said first and second output pulses of said comparing means, differentiating circuit means coupled to the outputs of said flip-flop means for providing a gating spike in time synchronism with each of said output pulses of said comparing means, and summing means responsive to the gating spikes for providing output pulses at twice the frequency of said integrating cycle.

Claim 7

In a measuring system, a frequency to voltage converter comprising: means for producing a frequency variable train of pulses, each of the pulse cycles of said train of pulses having the corresponding periodicity of the variable input frequency and each said pulse having a substantially constant pulse width; means for voltage converting said pulse cycles of said train to form a substantially square wave signal varying plus and minus of a reference level, said deviations of one polarity having a substantially constant width synchronized with said constant width pulses and said deviations of said other polarity being synchronized with the remainder of each pulse cycle; a voltage source having an output signal; series-shunt chopper means, coupled to said square wave signal, for modulating said voltage source output signal during said plus deviations; flip-flop means for gating said voltage converting means and single shot multi-vibrator means, responsive to said flip-flop means, for resetting said flip-flop means to produce said pulses having a substantially constant pulse width; and means for averaging the modulated output signal of the voltage source to provide an averaged output voltage which is proportional to the product of the modulated output signal of the voltage source and the input frequency.

Claim 8

In a measuring system, a frequency to voltage converter comprising: means for producing a frequency variable train of pulses, each of the pulse cycles of said train of pulses having the corresponding periodicity of the variable input frequency and each said pulse having a substantially constant pulse width; means for voltage converting said pulse cycles of said train to form a substantially square wave signal varying plus and minus of a reference level, said deviations of one polarity having a substantially constant width synchronized with said constant width pulses and said deviations of said other polarity being synchronized with the remainder of each pulse cycle; a voltage source having an output signal; series-shunt chopper means, coupled to said square wave signal, for modulating said voltage source output signal during said plus deviations; flip-flop means for gating said voltage converting means and single shot multi-vibrator means, responsive to said flip-flop means, for resetting said flip-flop means to produce said pulses having a substantially constant pulse width; and means for averaging the modulated output signal of the voltage source to provide an averaged output voltage which is proportional to the product of the modulated output signal of the voltage source and the input frequency.

Claim 9

The measuring system of claim 6 wherein said voltage source having an output signal includes second output signal means for producing an adjustable D.C. voltage which when added to the averaged output voltage of said averaging means provides an adjustable D.C. bias.