SU1115031A1 - Ac voltage calibrator - Google Patents

Abstract

A CALIBRATOR FOR VARIABLE VOLTAGE, containing a series-connected master oscillator, a regulating element with a discretely controlled transmission coefficient and a power amplifier, the output of which is connected to the output terminal and input of the measuring converter, the output connected to one of the comparison node inputs, and also a key connected to the output of the node comparison, the source of the reference voltage, a storage element and a pulse counter, characterized in that, in order to expand its functionality, The summation unit, analog-to-digital converter, shift registers, memory unit, reference analog converter, zero signal extraction unit, time shift unit and amplifier, the summation unit being the first inputs connected to the outputs of the analog-digital converter whose input is connected to the output of the storage element , the second inputs to the control inputs of the regulating element with discretely controlled transmission coefficient and to the outputs of the shift registers, and the outputs to the inputs of the shift registers the gistrov, the storage unit with the first input is connected to the terminal for connecting the control source, the second input to the output of the pulse counter, and the output from the first input (L d of the reference digital-analog converter, the second input of which is connected to the output of the source of the reference voltage, and output - with another input of the comparison node, the input additional output of the generator's oscillator is connected via the signal extraction unit of signal zeros to the synchronization inputs of the SP of the shift registers, the input of the counter; Pulses and the input of the time block This is the first output of the key connected to the control input and the second output to the synchronization input of the input element, the signal input of which is connected through the amplifier to the key.

Description

The invention relates to electrical engineering, in particular, to alternating voltage calibrators, and can be used in the construction of information-measuring systems and systems for automatic monitoring and control.  A variable voltage calibrator is known, which contains a master oscillator, to the output of which a regulating element is connected, a differential comparator, an amplifier, a source of reference voltages, a selective wiring circuit, a linear detector, a switch and.  pulse counter.  This device allows to obtain amplitude-moly / linear amplification, the values of the carrier signal and the modulating frequency of which are calibrated by the amplitude or effective value of the SR.  It does not provide a device for stabilization.  consequently, the installations with a high accuracy of a given shape (values) of the output signal envelope, which makes it impossible to calibrate it.  spectrum, since the spectrum of the calibrator output signal is uniquely related to the shape of its calibrator.  I The closest to the invention to the technical essence is an alternating voltage calibrator, containing a sequentially driven master oscillator, a control element with a discretely controlled transmission coefficient and a power amplifier whose output is connected to the output terminal and to the input of the measuring converter, the output connected to one of the the inputs of the comparison circuit, as well as the key connected to the output of the comparison circuit, the source of the reference voltage, the storage element and the pulse counter 21.  The known calibrator cannot be used to obtain amplitude modulated according to an arbitrarily given law of alternating voltage, the discrete values of which (amplitude values of the carrier oscillation) can differ significantly from each other in each half-period of the carrier oscillation and must be stabilized and specified with high accuracy , which makes it possible from the initial oscillation of a precision waveform, for example, a sinusoidal oscillation, which is a purely harmonic signal l, by means of its amplitude modulation, to receive test signals at the output of the calibrator, having a predetermined spectrum in a wide frequency band, a spectrum that can be easily tuned and calibrated with high accuracy.  The development of a corrective action, formed in accordance with a given value of the amplitude of the carrier oscillation in one, for example Kth, its period (half-period) will occur in the subsequent (K + 1) -and period (half-period) of the carrier oscillation, when the amplitude value of the carrier oscillation should already be different and may differ significantly.  In addition, the process of developing a given value of the amplitude of the output signal in a known device occurs over several periods of the carrier oscillation.  T. e.  Due to the limited speed of the stabilization system, the calibrator does not provide stabilization and, therefore, installation with a high accuracy of the specified values (shape) of the output envelope of the amplitude-modulated signal, which prevents its spectrum.  Thus, a disadvantage of the known device is the impossibility of its use for obtaining test signals, having a predetermined wide band of frequencies, a spectrum which is easily tuned and calibrated with high accuracy by amplitude modulation of the initial oscillation of a precision waveform.  As a result, the functionality of the known device is largely limited.  The aim of the invention is to enhance the functionality of the ac voltage calibrator.  The goal is achieved by the fact that an alternating voltage calibrator containing a series-connected master oscillator, a regulating element with a discretely controlled transmission coefficient and a power amplifier, the output of which is connected to the output terminal and input of the measuring converter, is output connected to one of the comparison node inputs, as well as a key connected to the output of the comparison node, a source-reference voltage, a memory element and a pulse counter, a summation unit, an analog-to-digital p eobrazovatel, shift registers, reference tsifroanalog. new; a converter, a storage unit, a signal zeros extraction unit, a time shift unit and an amplifier, the summation unit being connected by first inputs to the outputs of the analog-digital converter, the input of which is connected to the output of the storage element, and the second inputs to the control inputs of the regulating element with discrete control the transfer coefficient and to the outputs of the shift registers, and the outputs to the inputs of the shift registers, the storage unit of the first input is connected to the terminal for connecting the control signal source , the second input to the output of the pulse counter, / and the output to the first input of the reference D / A converter, the second input of which is connected to the output of the reference voltage source and the output to another input of the reference node, the input additional output of the master oscillator to the synchronization inputs of the shift registers, the input of the pulse counter and the input of the time shift unit, the first output of the key connected to the input of the control, and the second output - of the input. synchronization of the storage element, the signal input of which through the amplifier is connected to the output of the key.  FIG.  Figure 1 shows a block diagram of a variable voltage calibrator; in fig.  2 shows an example of constructing a block for zeros of a signal; Fig. 3 illustrates an example of constructing a time shift block; in fig. A are time diagrams that show the operation of an ac voltage calibrator.  The ac voltage calibrator contains a master oscillator 1, the first output of which is connected via serially connected regulating element 2 with discretely controlled transmission coefficient and power amplifier 3 to the output terminal 4 and to the input of the measuring transducer body 5, the output connected to the first input of the comparison node 6, the second input of which through the reference digital-to-analog converter 7 is connected to you-I, the course of the source 8 of the reference voltage 11 1 and the output through a serially connected switch 9, amplifier 10 and memory Element 11 is connected to the input of analog-digital converter 12, outputs connected to the first inputs of summation unit 13, the second inputs of which are connected to control inputs of regulating element 2 with discretely controlled transfer coefficient and outputs of shift registers 14, and outputs to inputs the shift registers 14, the block 15 allocation of zeros of the signal, the input connected to the second output of the master oscillator 1, and the output connected to the synchronization inputs of the shift registers 14 to the input of the counter 16 pulses and to the input of the bl 17 time shift, the first output of which is connected to the control input of the key 9, and the second output to the synchronization input of the storage element 11, as well as the storage unit 18, the first input connected to the calibrator input of the modulation law setting code, the second input to the output of the counter 16 pulses, and the output - to another input of the reference tf and analogue converter 7.  Block 15 for the purpose of signal zeros (FIG.  2) contains the amplifier-limiter 19, pulse shapers on a positive 20 and a negative 21 signal differential and circuit OR 22 ,.  The time shift block 17 (FIG. H) contains a generator 23 clock and waves, frequency divider 24, counter 25 pulses, one-shot 26, pulse counter 27, trigger 28, AND circuit 29 and drivers 30 and 31.  The master oscillator 1 is, for example, an RC oscillator that generates a harmonic signal of a precision form, a regulating element 2 with a discretely controlled gain, a digital code controlled multi-voltage voltage divider, a measuring converter 5 is a full-wave rectifier that generates module. the calibrator output signal, the memory element 11sample of storing the analog signals, with which the level and output of the output voltage of the amplifier 10 are sampled and memorized at the time of arrival of the control pulses, to the synchronization input, summation block 13 is a binary combinator numbers The shift registers 14 are designed to store the control codes of the transmission coefficient of the regulating element 2 and sequentially feed them to the control inputs of the element 2 in phase with the output signal of the master oscillator 1.  In this case, the control code in the form of a parallel binary code is removed from the outputs of the last bits of the shift registers 14 when the information written in the registers 14 is shifted by one bit.  The storage unit I8 is an operational, permanent, or reprogrammable read-only memory.  The storage devices generally have two groups of main inputs: the inputs for setting the address of the memory cells in which information is stored (this group of inputs is connected to the output of the pulse counter 16), and the inputs for recording information in the memory cells (when using the permanent memory devices no input group).  The recording inputs connected to the calibrator input are given a control signal in the form of a code.  In this cell. The memory of block 18 is entered into a set of I codes of the amplitude values of the calibrator generated at the output. msh1 tuduno-modulated signal in each half of its carrier oscillation t. e.  A set of codes of discrete values of the calibrator output signal, defining the law of its modulation.  The number of bits of the shift registers 14 is equal to the number of used memory cells of the memory unit 18.  The ac voltage calibrator operates as follows.  To the input of an adjustable element 2 with a discretely controlled transmission coefficient from the first output of the master oscillator. 1 a very harmonic waveform approaches the furthest shape (FIG. 4a), a group of digital transmission control codes is applied to the group of digital control inputs, which is removed from the outputs of the last bits of the shift registers 14.  The change in the transmission coefficient of the regulating element 2 occurs at the moments when the output signal of the back-up generator 1 is crossing the zero level and occurs as a result of shifting the control codes recorded in the registers 14 by one bit.  16 For this with. The second (auxiliary) output of the master oscillator 1 is taken off the signal, the common mode signal at its first (main) output, and is fed to the input of block 15, at the output of which short pulses are formed (Fig.  4d) at the moments of transition of the input signal through zero.  These pulses arrive at the synchronization inputs of the registers 14 and clock the information shift in them by one bit.  The signal from the output of the regulating element 2 through the amplifier 3. power is supplied to the output terminal of the calibrator 4.    The counter 16 pulses counts the pulses from the output of block 15. The output code of the counter 16 is changed and sets the address of the memory cells of block 18.  As a result, the contents of the memory cells of the storage unit 18 are sequentially polled, in which a set of codes is entered, which sets the law for modulating the output signal of the oscillator 1 and represents the set of amplitude codes of the amplitude-modulated signal generated at the calibrator output in each half-period of its carrier oscillation, t . e.  set of codes of discrete values of the envelope of the output signal of the calibrator.  Codes recorded in the memory cells successively appear at the output of block 18 and arrive at the digital input of the reference digital-to-analog converter 7, to the reference input of which the DC voltage from the output of the source 8 of the reference voltage is applied.  At the same time, at the output of the converter 7 connected to the second input of the comparison node 6, periodic cycles sweep the reference signal formed by the converter 7 (Fig. 4e), which is used as a modulating signal.  At the first input of the comparison unit 6, a signal is applied (FIG. 4c) from the output of the measuring converter 5, which forms the module of the output signal of the calibrator.  Using key 9, which is controlled by pulses from the first output of the block 17 of the time shift (Fig.  4e), short durations are taken, much shorter than the half-time duration of the carrier oscillation, the samples from the output signal of the comparison node 6 at the times when the signal is at the output of the gauge 7.  1 torus (FIG.  46) takes its amplitude values equal to the envelope values.  For this purpose, unit 17 shifts by half a period of pulses from the output of unit 15.  With the help of a storage element 11, the fixation of the input signal of which is synchronized with the moments of sampling from the output signal of node 6, the amplified using the amplifier GO and the extended pulse signal of the error signal generated at the output of the key 9 is memorized.  The pulses of control of the latching of the input signal level of the storage element I1 are fed to its clock; input from the second output of block 17. The constant voltage generated at the output of the storage element 11 in each half-period of the oscillating wave (FIG.  4g) is proportional to the error signal and is measured by an analog, digital-to-digital converter 12.  Let in the first scan cycle of the reference signal (FIG. 4e) the control code on digital inputs of control element 2 is zero. Then the output per calibrator of FIG. 4b) is also zero but the error signal is equal to the values of the reference signal. In this case, sequential reading of the values of the reference signal and filling the bits of the shift registers 14 occurs.  By the end of the first sweep cycle, the last bits of the shift registers 14 will contain information about the value of the output signal of the calibrator, which must be set in the first half of its carrier wave, and in the first bits - information about the value of the output signal of the calibrator that needs to be set, half period of its carrier oscillation. From the second sweep cycle of the reference signal, the error signal read in each half-period of the carrier oscillation will correspond to the control code that was formed at this time on the outputs of the last bits of the shift registers 14.  The control coefficient code of the regulating element 2 is summed with the corresponding error signal code in the summation block 13 and is fed to the inputs of the first orders of the shift registers 14.  Under 1 action of clock pulses from the output of block 15, the control code with the entered correction is rewritten into registers 14 in their first bits, and in the subsequent cycle this code with HjiyanoM corresponding to its half period of carrier oscillation again appears at the outputs of the last bits of shift registers 14 and affects the control inputs of the regulating element 2.  In this case, the correction signal generated in the previous cycle is tested.  T. e.  the reading of the error signal and the operation of working out the correction action aimed at reducing this error signal occur in the same (for example, Kth) half-time carrier wave, and the error signal is read in one cycle of the reference signal sweep, and the operation of working out the correction effect - in the subsequent cycle in the corresponding half-period of the carrier oscillation.  At the same time, the inertia of the stabilization system due to the lateral testing of the corrective action (unlike the known devices) does not affect the accuracy of setting the specified amplitude values of the amplitude-modulated signal generated at the calibrator output into each separately taken half-period of its carrier oscillation.  In the process of stabilizing the calibrator output values, the information recorded in the shift registers 14 is changed due to corrections due to the difference between the amplitude values of the output signal and the reference signal used as the pre-sampling at the time points of sampling.  After several cycles of the reference signal sweep (FIG. 4e) the amplitude values of the calibrator output signal (FIG.  4b) in each half period of its carrier oscillation becomes equal to the values of the reference signal, and the error signal then tends to zero (Fig. 4g). As a result, the discrete values of the envelope of the output signal of the calibrator are set to the given values.  Blocks 1–3, which form the direct path to form the output signal of the calibrator, can be made inaccurate, and the discrete values of the output signal envelope do not depend on the instability of their transmission coefficients as well as on the instability of the amplitude of the initial oscillation taken from the first output of the master oscillator 1, If it is necessary to receive a signal at the output of the calibrator, the amplitude of which is constant, identical amplitude value codes are entered into the memory cells of the storage unit 8.  As a result, during the sequential polling of the contents of the memory cells of block 18, a constant level of the reference signal is formed at the output of the digital-to-analog converter 7.  Signal extraction unit 15 (FIG.  2) works as follows.  The input signal of the unit 15 is amplified and limited in amplitude by the limiting amplifier 19. From the positive and negative drops of the output signal of the amplifier I9 using shapers 20 and 21, respectively, which are single vibrators, short pulses are formed, which coincide with the zero-crossing times of the output signal of the master oscillator 1.  These pulses are summed at the output of the ShSh 22 circuit and are fed to the output of the block 15. H) performs a time shift to the floor.  period of the pulse sequence from the output of the block 15 and the formation of the pulses controlling the key 9 and the storage element 11.  The pulses from the generator output 23 clock pulses through the divider 24 frequency by two are received on o, the even 1 input of the counter 25 pulses.  The counter 25 is periodically reset to the zero state by pulses from the output of the block 15, which arrive at the input of the installation to the zero state of the counter 25 with some delay through the one-shot 26. The output pulses of the unit 15 are also fed to the preset control input of the pulse counter 27 and to the installation input to the trigger state 28.  In this case, the counter code 25, before it is reset to the zero state, is rewritten into counter 27, and the output signal of the trigger 28 allows the clock pulses of the generator 23 to pass through the AND circuit 29 to the counter input of the counter 27. In this case, counter code 27 is written off. After a half-period of the output pulses of the block 15, the write-off occurred. counter code 27, a pulse is formed at its output, which triggers the drivers 30 and 31 of the output control pulses. apo  passing element 11 and key 9, respectively.  Output pulse counts.  KA 27 also sets in the initial zero state a trigger 28, which prohibits the passage through AND circuit 29 to the counting input of the counter.  27 clock pulse generator 23.  Thus, the calibrator provides stabilization and setting, with high accuracy, the amplitude values of the amplitude-modulated signal generated at the calibrator output in each separately taken half-period of its carrier oscillation.  At this, the form of the carrier oscillation in each half-period does not distort; is strictly defined and determined by the shape of the original oscillation.  This makes it possible from the original oscillation of a precision waveform, for example, a sinusoidal oscillation, which is a purely harmonic signal, due to its amplitude modulation to receive various test signals at the output of the calibrator, which are specified in a wide frequency band, easily tunable and calibrated with high precision spectrum.  As a result, the functionality of the proposed calibrator is expanded. The spectrum of the signal being generated at the calibrator input is determined by the shape of the carrier wave, which is strictly specified, and the law of amplitude modulation.  By changing the modulation law, which can be easily realized when recording the memory block of the new set of codes for the calibrated values of the envelope of the output signal of the calibrator, it is possible to set any predetermined spectrum of the calibrator's signal.  In the particular case of the modulation law, when the amplitude of the carrier oscillation in each of its half-periods alternately takes one of two fixed values, the output signal is a capib11. 111503112

The rator contains only the main and external source of signals with calibrated harmonics. With this calibrated coefficient, the nonlinear coefficient can be used as an indication.

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FIG. 2

Claims (1)

VARIABLE VALVE CALIBRATOR, comprising a serially connected master oscillator, a control element with a discrete up-, equal transmission coefficient and a power amplifier, the output of which is connected to the output terminal and the input of the measuring transducer, the output connected to one of the inputs of the comparison node, as well as a key connected to the output of the comparison node, the reference voltage source, a storage element and a pulse counter, characterized in that, in order to expand the functionality, it introduced summation, analog-to-digital converter, shift registers, memory block, reference digital-to-analog converter, signal zero block, time shift block and amplifier, and the summation block with the first inputs connected to the outputs of the analog-digital converter, the input of which is connected to the output storage element, the second inputs to the control inputs of the regulating element with a discretely controlled transmission coefficient and to the outputs of the shift registers, and the outputs to the inputs of the shift registers, the memory lock, the first input is connected to the terminal for connecting the control signal source, the second input to the output of the pulse counter, and the output to the first input of the reference digital-to-analog converter, the second input of which is connected to the output of the reference voltage source, and the output to the other input of the comparison unit , the introduced additional output of the master oscillator through the block of separation of the zeros of the signal is connected to the inputs of the synchronization of the shift registers, the input of the counter ^ pulses and the input of the time shift block, the first output connected to the key control input and the second output - to an input of the synchronization storage element, the signal input of which via an amplifier is connected to the output of the key. rcusTTT’Tis ^ 1 115031