초록 ▼

The output of the sensor whose variations are to be compensated is applied to one input of a DC amplifier whose other input is connected to an analog storage. The output of the DC amplifier is applied to a voltage-controlled oscillator whose frequency varies as a function of the voltage applied ther

The output of the sensor whose variations are to be compensated is applied to one input of a DC amplifier whose other input is connected to an analog storage. The output of the DC amplifier is applied to a voltage-controlled oscillator whose frequency varies as a function of the voltage applied thereto. A phase detector compares the output of the voltage controlled oscillator to a standard reference frequency and furnishes a DC compensating voltage corresponding to the difference therebetween. Prior to each measurement the DC compensating voltage is applied to the analog storage thereby forming a closed loop circuit and causing the voltage controlled oscillator to oscillate at its standard frequency. At the start of the measurement the connection between the phase detector and the analog storage is broken thereby causing the DC compensating voltage present at the beginning of the measurement to be applied to the DC amplifier throughout the measurement. The frequency of the output of the voltage controlled oscillator then varies as a function of the sensed signal and is counted by a counter controlled by timing signals derived from the oscillator furnishing the standard frequency signal to the phase detector.

대표청구항 ▼

In measurement equipment having sensor means for furnishing a sensor output signal indicative of the value of a measured characteristic and wherein said sensor output signal undergoes undesired variations as a function of at least one factor other than said measured characteristic, equipment for com

In measurement equipment having sensor means for furnishing a sensor output signal indicative of the value of a measured characteristic and wherein said sensor output signal undergoes undesired variations as a function of at least one factor other than said measured characteristic, equipment for compensating for said undesired variations, comprising, in combination, DC amplifier means having a first input connected to said sensor means for receiving said sensor output signal, a second input, and an amplifier output, for furnishing an amplifier output signal varying as a function of signals at said first and second inputs at said amplifier output; analog-digital converter means connected to said DC amplifier means for furnishing a digital signal having a frequency corresponding to said amplifier output signal; stabilized oscillator means for furnishing a frequency stabilized signal; phase detector means connected to said analog digital converter means and said stabilized oscillator means for furnishing a DC compensating voltage varying as a function of the phase difference between said digital signal and said frequency stabilized signal; storage means connected to said second input of said DC amplifier means; and means for connecting said storage means to said phase detector means prior to each measurement thereby creating a closed loop circuit, and for disconnecting said storage means from said phase detector means during each measurement, whereby the value of said DC compensating voltage immediately preceding each measurement is maintained during said measurement.