SU1023251A1 - Two-terminal network parameter meter - Google Patents

Abstract

A RHC-PARAMETER METER OF TWO-POLES, containing a controlled operating frequency generator, a frequency converter, one of the inputs of which is connected to the first terminal for connecting the measured two-terminal and an exemplary measure, an intermediate frequency amplifier connected to one of the inputs of the measuring and computing node, the other input of the last connected to the output of a controlled operating frequency generator, the input of which is connected to the control output of the measuring and computing node, characterized in that, in order to measurement accuracy, the output of the controlled frequency generator is connected to the second terminal for connecting the measured two-terminal network, the output of the frequency converter is connected to the reference measure input through an intermediate frequency amplifier, and the control output of the measuring and computing node is connected to another frequency converter input

Description

Yu

soh

The invention relates to an electrical radio-measuring technique and is intended to measure the passive parameters of two-terminal networks over a wide frequency range. Known impedance meter with the holding support generates p dvuhkana flax stroboscopic transformative Tel, reference resistor, controlled emy phase shifter controlled by attonyuaJOP two keys, a differential amplifier, impedance equilibration phase shifter confine nichiteli, gated amplifiers yn ikatory zero body inverting amplifier rz. The disadvantage of such a meter is that the measurement error includes the conversion error of the reference and signal channels of the strobe-scope transducer. The closest technical solution to the invention is a converter of parameters of complex resistances to voltage, containing a frequency converter, modulators, a sample measure, a source of operating voltage, and a source of voltage of a fixed frequency 23. The disadvantage of the prototype is that the modulator error is fully included in the conversion error. The purpose of the invention is to increase the measuring tonality. The goal is achieved by the fact that in the KHC-parameters of two-terminal network, containing a controlled operating frequency generator, a frequency converter, one of the inputs of which is connected to the first terminal for connecting the measured two-bend and an exemplary measure, an intermediate frequency amplifier connected to one of the inputs - computing node, another input after it is connected to the output of the controlled operating frequency generator, the input of which is connected to the control output of the measuring and computing node, d controllably operating frequency of the generator is connected to the second terminal for coupling the measured two-terminal network, the output of the frequency converter through an intermediate frequency amplifier connected to the input of the exemplary measure and control output measuring and computing node is connected to another input of the frequency converter. The RhC-pair-two-terminal meter contains a controlled operating frequency generator 1, a first digital voltmeter 2, a controlled two-pole 3, a frequency C converter, sample measure 5 and the output of the frequency converter t is connected via an intermediate frequency amplifier 6 to the second pole of model measure 5 and to the input of the second digital voltmeter 7, a strobe pulse generator 8, an output connected through a gate driver 9 strobe pulses to the second input of the frequency converter C, in addition, a digital reading device 10, a controlled operating frequency generator 1, digital voltmeters 2 and 7, and a strobe pulse generator 8 are connected via interface 11 to microprocessor unit 12, these nodes being measuring and calculating node 13. The RhC parameter of two-terminal devices works as follows. At the output of the operating frequency generator 1, controlled via the interface 11 by the microprocessor unit 12, a high-frequency voltage and a required frequency 05 are applied, which is fed to the first terminal of the controlled two-terminal 3 and the digital voltmeter 2. The voltage from the second terminal of the controlled two-pole 3 is fed to the converter k frequencies. Generator 8 gating pulses, micro-controlled. processor unit 12, through the driver 9 gating pulses produces gating pulses with a duration of 0.6-0.9 NS to the second input of the frequency converter k. The frequency of strobe pulses is calculated with microprocessor unit 12 from the ratio pr so that regardless of the value of the specified operating frequency, the intermediate frequency at the output of the frequency converter is constant, valid 20 kHz. The voltage of the converted frequency Unp from the output of the frequency converter j is amplified by the intermediate frequency amplifier 6 and, through reference measure 5, the amplified voltage Uge is fed to the input of the frequency converter. 3. 10 where it is summed with the high frequency voltage of the operating frequency. The total voltage is gated and at the time points of gating to the input frequency converter k there is a noncompensation voltage. When the gain of the intermediate frequency amplifier 6 is sufficiently high, the voltage at the input of the frequency converter at frame times tends to zero. As a result, the influence of the parameters of the monitored two-terminal 3 on the transmission coefficient of the frequency converter k is eliminated, and the influence of the multiplicative error of the blocks of the frequency converter k and the intermediate-frequency amplifier 6 is reduced. The voltages taken from the outputs of the controlled generator 1 of the operating frequency and the amplifier 6 intermediate, the frequencies are measured by digital voltmeters 2 and 7, the information on the measurement results through the interface 11 is recorded in the microprocessor unit 12. According to the values of these voltages microprocessor unit 12 calculates the RVtC parameters of a controlled two-terminal 3 given a working and converted frequency. Let us consider the operation of a two-terminal RHC meter using the example of capacitor capacitance measurement. In capacitor capacitance measurement mode, reference inductance capacitors and resistors can be used as an exemplary measure. With a large gain amplifier 6, you can write the ratio iH Uoc:. X ska where Nose is the voltage of a low fixed converted frequency inp taken from the output of amplifier 6 of the intermediate frequency, Xs is the capacitance of the measured condensate C at the frequency {of the input voltage U l and equal to QTt-f g Bx is the capacitance of the reference capacitor on the frequency f at the converted voltage and equal to By substituting the values for capacitances x and in (1), we obtain the ratio x-2ft ex x Uoc2 {npC3. After converting Cj (defined as Cx-gr ix. Denoting k as a ratio of 6%, ig of the conversion transmission, the transformation ratio of the frequency converter k, we get 4 From expression (3) it can be seen that the capacitance of the reference capacitor to the transformation ratio is larger than the measured In addition, the reference capacitance operates at a fixed low frequency, for example, 20 kHz, and at such frequencies our industry produces stores of reference capacitances certified with an error of 0, p1% or less. The RVjC meter -parameters of two-terminal circuits Measurement C operates as follows. The microprocessor unit 12, via interface 11, sets the required operating frequency f Q, which is removed from the output of the controlled operating frequency generator, and the determined gating frequency 1 cfp, taken from the generator output 8 gating pulses. Moreover, the ICTP strobe pulse frequency is set so that the converted frequency is fixed and equal, for example, 20 kHz, i.e. The following relationship between frequencies should be observed: 7 where N is the number of periods Tg of the operating frequency,. which is laid down in the TSTR period of "1 / ic-tp trail", J- - of gating pulses, N- 1,2,3 ... After that, in the micro processor unit 12, the transformation ratio Q is calculated. At the same time, a digital voltmeter 2 and 7 command is given to measure the amplitude of the voltages UBX Ugj. The results of measurements through the interface 11 are stored in the memory of the microprocessor unit 12, where and 0 516 the capacity C is calculated by the relation (3). The meter also allows small capacitances to be measured in tenths of picoforads by the values of large reference capacitances, the nominal values of which, in the transfermation coefficient, are O times larger. Measurement of inductance and resistors is similar. Thus, in the two-terminal parameter meter, which is preliminarily measured, the measurement accuracy is increased in comparison with the prototype.

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Claims (1)

RhC-ΠΑΡΑΜΕΤΡΟΒ TWO-POLE METER, containing a controlled operating frequency generator, a frequency converter, one of the inputs of which is connected to the first terminal for connecting the measured two-terminal and exemplary measures, an intermediate frequency amplifier connected to one of the inputs of the measuring and computing unit, the other input of the last connected to the output of a controlled operating frequency generator, the input of which is connected to the control output of the measuring and computing node, characterized in that, in order to increase accuracy measurement output managed operating frequency of the generator is connected to a second terminal for connection of the measured two-terminal network, the output of the frequency converter through an intermediate frequency amplifier coupled to the input of an exemplary action, and the control output I measurement and numeral I You are a node connected to the other | frequency converter input · I f IO2325I