SU909596A1 - Method and device for parametric measuring converter amplitude characteristic linearization - Google Patents

Description

The invention relates to a measurement technique and can be used to reduce the systematic error due to the non-linearity of the amplitude characteristics of the measuring transducers.

The known method of linearization of the amplitude characteristic of the converter, concludes with comparing the signals of two differential measurement arms and compensating for the non-linearity of the converter tU.

However, the known method does not provide the required accuracy of linearization.

The closest in technical essence to the proposed method is the linearization of the amplitude characteristic of a partimetric measuring transducer, consisting in the initial calibration of two transducer channels, the linearization of the calibration curve by changing the transform coefficient of the transducer using nonlinear links and re-grading of the G2 converter.

The disadvantages of this method are the lack of accuracy of linearization.

The purpose of the invention is to simplify the linearization characteristics.

This goal is achieved by changing the output voltage K times for the first channel and in Kg | once for the second channel, keeping the ratio,) const, then the indicated

10, the voltage is compared with the reference signal, and the error signal is used as a control to the entire signal to change the conversion factor of the converter.

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The drawing shows the device regshizuyuschee the proposed method.

The device contains a light source 1, a polarization-optical system 2, photodetectors 3 and 4, a total of 20 tor 5, a comparison unit 6, a reference voltage unit 7, a controlled power supply unit 8, scaling units 9 with different transmission coefficients, differential outputs 10 and 11 channels 25 converters.

The feedback circuit, encompassing the converter and consisting of scaling units 9, adder 5, comparison unit 6, controlled power supply unit 8, maintains the sensitivity of the converter continuously leading to zero the difference between the signals received at comparison unit 6 from adder 5 and unit 7 reference stress. Maintaining the sensitivity of a constant is accomplished by changing the power of the source of light 1, illuminating through the polarization-optical system 2 the photodetectors 3 and 4.

If the transfer coefficients K and K of the scaling units 9 are of equal magnitude, then the sensitivity of the converter remains constant even when the polarization-optical system 2 is loaded by force P. This is explained by the fact that the increments of the voltage at the input of the adder, caused by the increment of force P, , have the same magnitude and different signs and, consequently, the signal at the output of the adder when the force P changes remains unchanged.

In the case when the transfer coefficients of the scaling units 9 are set unequal, the voltage increments become unequal, the action at the input of the adder when the force P varies (although the increments of the voltage of the photoreceivers are still equal). As a result, the signal at the output of the adder, and hence at the output of the comparator unit, varies in proportion to the power P. The controlled power supply unit, tends to bring the signal at the output of the comparator unit to zero, changes the current, thereby automatically changing the sensitivity of the converter as the power increases. R. This automatic change in the sensitivity of the converter during the measurement process leads to the appearance of an artificial nonlinearity of its amplitude response. The sign of this non-linearity depends on the signs of the variation of the coefficients and K ", and the magnitude depends on their magnitude.

This artificial non-linearity is used to compensate for the natural non-linearity of the amplitude response of the converter.

The method of reducing (correcting) the nonlinearity of the amplitude characteristic of the converter is performed in the following way.

Having obtained the amplitude characteristic of the converter with the same transmission coefficients K and K, scaling and determining the non-linearity K, the transmission coefficients K are changed and their sum remains the same. If the re-obtained amplitude response has less non-linearity than the original, then the coefficients K and K ij change in the same direction and the amplitude response is determined again and so on until the minimum non-linearity is obtained. After that, K and K ij are fixed for the values found.

If at the first change of the coefficients the nonlinearity increases, then the same operations are carried out, changing the coefficients K and K, in the opposite direction.

Claims (2)

1. A method for linearizing the amplitude characteristic of a parametric measuring transducer, consisting in the initial calibration of two transducer channels, linearizing the calibration curve by changing the transform ratio of the transducer using nonlinear links and re- Calibration of the converter, characterized in that, in order to simplify the linearization of the characteristic, the output voltage is changed by K times for the first channel and K / time for the second channel, the ratio is + K2 const, then the voltages are compared, the total signal is compared with reference, and the error signal is used as a control signal of the converter to change the conversion factor of the converter. 2. A device for carrying out the method of Claim 1, comprising an adder, the reference voltage unit, the comparison unit and the controlled power supply unit, the totalizer inputs connected to the differential outputs of the channels, the outputs of the adder and reference unit the voltages are connected to the inputs of the comparison unit, and the output of the latter to the input of the controlled power supply unit, characterized in that scaling units are introduced into it with different transmission ratios connecting the outputs of the differential channels of the converter with the inputs of the adder. Information sources, taken into account in the examination 1. Patent of Great Britain No. 1371222, cl. G 01 N, pub. 1956 2. Konchalovsky V.Yu. et al. Electrical Transmitters. M., Energie, 1967, p. 180186 (prototype). 2-, y