SU938181A1 - Method and device for measuring signal period - Google Patents

Description

The invention relates to measuring equipment and can be used, for example, in the processing of signals from photovoltaic converters.

There is a method of measuring the time interval ^{5, which} consists in comparing the input signal with a given threshold level, generating at the moment the signal crosses the level _{) 0} pulses of the beginning and end of the interval, counting pulses of the reference frequency for a time limited by pulses of the beginning and end of the interval G1]. fifteen

This method has low accuracy, due to the presence of errors in the formation of pulses of the beginning and end of the interval due to the instability of the threshold level. 20

The closest to the invention by the technical essence is a method for measuring the period of ^{quasi-one-ethnic} signal by quantizing the reference frequency pulses the time interval between two closest transitions of the signal at a fixed level, after fixation point of intersection of the core layer, the additional intersection points, increasing one another, fixed levels, increase at the first intersection of each increasing level of the quantization frequency by the value of the reference frequency, decrease at repeated intersection of each increasing level of the quantization frequency by the value of the reference frequency, counting the number of quantization pulses that changes frequently [? J ·

The disadvantage of this method is the low accuracy of the period measurement, due to the presence of measurement errors due to the instability of the zero level and the amplitude of the input signal.

The device closest to the invention in technical essence is a digital infra-low-frequency periodometer containing a comparison circuit, a digital-to-analog converter, a counter, a control unit, two triggers, a reference frequency generator, a controlled frequency multiplier, a counting unit and keys [3J.

The disadvantage of this device is the low accuracy of the period change due to the presence of a measurement error caused by the instability of the zero level and amplitude of the input signal.

The purpose of the invention is to improve the accuracy of the measurement period due to the elimination of measurement errors due to the instability of the zero level and amplitude of the input signal. _;

This goal is achieved by the fact that according to the method of measuring the signal period by pulses quantizing the reference frequency of the time interval between the two nearest transitions of the signal through a fixed level, fixing after the moment of crossing the main level the moments of intersection of additional fixed levels increasing one after another, increasing at the first crossing of each increasing the level of the quantization frequency to the value of the reference frequency, while counting the number of quantization pulses I of a changing frequency, following the fixation of the moments of intersection of additional levels increasing one after another, they fix the moments of intersection of additional “decreasing fixed levels one after another, increase the quantization frequency from zero to the value of the reference frequency at the first intersection of each decreasing level, at the repeated intersection of each increasing level and the repeated intersection of each decreasing level, simultaneously count the number of crossed level signals, the number of quantization pulses reference frequency in the time intervals between the moments when the signal intersects the main upper decreasing levels, between the moments of the intersection of the upper increasing and decreasing levels, and the value of the period is determined by their value.

To a device consisting of a comparison unit, digital-to-analog conversion

JO of the caller, counter, control unit, two triggers, a reference frequency generator, a counting unit, and a controlled frequency multiplier, the input of which is connected to the output of the reference frequency generator, the input of which is connected to the output of the first trigger, the zero-setting input of which is connected to the output of the comparison unit and a summing counter input, the code output of which through a digital-to-analog converter is connected to the first input of the comparison unit, and the loan transfer output is connected to the counting input of the second trigger, the output of which is connected to the account the input of the first trigger, and the output of the controlled frequency multiplier is connected to the counting input of the counting unit, while the second input of the comparison unit is connected to the output of the control unit, three counting units, a calculation unit, a comparison unit, a trigger and a one-shot, the output of which is connected to the inputs, are additionally introduced control of the main and first and second additional counting units, the first and second control inputs of the third additional counting unit and additional trigger are connected respectively to the outputs of the main and additional of the comparison blocks, the output of the additional comparison block is connected to the input of the subtraction of the counter, the loan output of which and the two outputs of the additional trigger are connected to the three corresponding inputs of the start of the one-shot, the output of which is connected to the input of the calculation block, the information inputs of which are connected to the outputs of the counting blocks, while the counting the inputs of the second and third additional counting units are connected to the output of the reference frequency generator, the counting inputs of the first additional counting unit are connected to the output of the main and additional comparison units, the first input of the second comparison unit is connected to the output of the digital-to-analog converter, and its control input is connected to the output of the control unit, and the output of the first additional account unit is connected to a controlled frequency multiplier.

In FIG. 1 is a timing chart explaining the proposed method, where 1a is an input signal, spaced onto a grid of levels, 16 is a scale value, 1c is a pulse of separation of time intervals; nafig. 2. functional diagram of the proposed device.

The essence of the method is $ the following sequence of operations.

The intersection is fixed by the signal of the main level. The main level is chosen above the level of noise that accompanies the signal. The time intervals are quantized by impulses of the reference frequency (when measuring dimensions, signals 15 from the linear displacement sensor can be used as impulses of the reference frequency). Following the moment of crossing the main level, the moments of intersection of additional, increasing one after another fixed levels 20 are fixed (the distance between the levels is chosen greater than the doubled amplitude of the noise superimposed on the signal). At the first crossing of each age <current level, the quantization frequency is increased by the reference frequency value (time interval 0-1, Fig. 1Q. The number of levels a ^ crossed by the signal is calculated. The current value of the result can be used to control the frequency increase coefficient The number of quantization pulses of varying frequency a ^ and the number of quantization pulses of the reference frequency in the time interval between the moments of intersection of the upper, increasing and decreasing levels, that is, are calculated. determine the value.

Following fixation points transferred additional section _40, increasing levels of one another additional fixed points of intersection, decreasing successive fixed levels. Each decreasing co- _4J level corresponds to an increasing fixed level. For example, the first decreasing corresponds to the penultimate ascending, the last decreasing, preceding the main, corresponds to the first ascending. Thus, the total number of decreasing levels is one less than the number of increasing ones.

At the intersection of each additional decreasing level, the quantization frequency is increased from zero by ^{55 by the} value of the reference frequency (time interval 1-2, Fig. 16), the number of quantization pulses from the changing and reference frequencies in the interval is calculated. The time between the intersection of the upper decreasing and the ground level a £ ^ and a ^^, as well as the amount of quantization of the reference frequency in the time interval between the intersection of the first trailing and second leading edges of the main level signal a ^ (time interval 2-3, Fig. 1c).

Once again, the intersection is detected by the signal of the main level, after the moment of crossing the main level, the moments of intersection of additional fixed levels increasing one after another are recorded.

Upon repeated crossing of each increasing level, the quantization frequency is increased from zero by the value of the reference frequency (time interval 3-4, Fig. 16). The number of levels crossed by the signal, the number of quantization pulses of the measured and reference frequencies in the time interval between the intersection of the main and upper decreasing levels a ^ d and a _{34 are calculated} , the number of quantization pulses of the reference frequency in the time interval between the intersection of the upper ascending and decreasing levels signal fixes the moments of repeated intersections of additional fixed levels decreasing one after another; increase from zero the quantization frequency by the value of the reference frequency at the intersection of each decreasing level (time interval 4-5, Fig. 16); count the number of quantization pulses of the varying and reference frequencies in the time interval between the signal crossing the upper decreasing and the main levels a 2 ^ 5 · and a · ^ ·

The value of the period is determined by the formula '+ cv) ~ Ca _i4 -1) “where q is the ratio of the durations of the trailing and leading edges of the signal.

The value is set according to a priori data on the ratio of the durations of the leading and trailing edges of the signal.

The device consists of units 1 and 2; comparisons, control unit 3, digital-to-analog converter 4, counter 5, triggers 6 and 7, a reference frequency generator 8, a controlled frequency multiplier 9, counting units 10-13, trigger 14, one-shot torus 15 and block 16 calculations.

Blocks 1 and 2 of comparison can be made in the form of a series-connected adder, threshold element, level converter, logic elements and a single-vibrator.

Controlled frequency multiplier 9 may be constructed as either a pulse train generator (the number of pulses in the burst is equal to the number of code 15 which is exposed at the control c5? Ode managed frequency multiplier) or _{of the} period as the divisor input signal by a predetermined number.

The device operates as follows 20 times.

At the initial moment, the counter 5, the triggers 6, 7 and 14, the blocks of the account 1013 are set to zero. The voltage of the digital-to-analog converter 25 is zero. According to the signal from the control unit 3, comparison units 1 and 2 are connected to the input of the device to which the measured signal is supplied. zo

Comparison levels are selected by the formulas

"E,’ ^υ θχ- (2) ^U cx and = cG DAC (3) 35 where u and and - - levels of comparison Cl Cove 1 and 2 comparisons respectively; 40 * ^U 8X ' w - values input straining and voltage FROM

from digital-to-analog converter 4;

- magnitude modulo ₄₅ quantum of the digital-to-analog converter 4.

When = (f (main level), the comparison unit 1 is triggered, the contents of counter 5 are increased by one to ⁵⁰ units, thus, the comparison levels are shifted to 1S and 0, the contents of block 10 are increased to unity, setting the coefficient of the controlled frequency multiplier to unity, trigger 6 is set to a single state and permits the operation of the generator 8 of the reference frequency, the pulses from which are supplied to the counting units 12 and 13 and through the controlled frequency multiplier 9 to the counting unit 11.

At the intersection of subsequent increasing levels, the multiplication coefficient increases, the counting unit 13 with each coincidence pulse is zeroed, so its contents correspond to the output of the register to the number of quantization pulses of the reference frequency, calculated in the time interval from the penultimate to the last crossed levels. When the comparison unit 2 is triggered for the first time, which corresponds to the intersection of the upper decreasing level (Fig. 1, time moment 1), the content of counter 5 decreases by one, shifting the comparison levels down, trigger 14 switches, triggering a one-shot 15, which resets the counting units 10, 11 and 12, block 16 exchanges data, while the numbers on the register outputs of the counting blocks 10, 11, and 12 correspond to the number of crossed increasing levels of a ^, the number of quantization pulses of increasing a ^, the main frequency a in the time interval between the first intersection by a signal of the main and upper decreasing levels and from the counting unit 13, to the number of quantization pulses of the fundamental frequency a. in the time interval between the upper increasing and decreasing levels. After zeroing, one is recorded in the counting unit 10, this is achieved by the fact that the zeroing pulse is generated by a single vibrator 15 along the leading edge of the pulse from comparison blocks 1 and 2, and the counting block 10 increases its content by one along the trailing edge of the pulse from comparison blocks 1 and 2. At the intersection of subsequent levels, the counting process is repeated, when a loan appears at the output of counter 5, which corresponds to the contents of counter 5 equal to one, a single vibrator 15 is activated, zeroing the counting units 10, 11 and 12 and indicating the exchange of block 16 with them, thus obtaining a ^, a52 "trigger 7 switches to a single state, counter 5 is reset.

Upon repeated intersection of the main level, the exchange processes and accounts are repeated. When the loan pulse reappears from the output of counter 5, trigger 7 switches to zero and transfers the trigger to zero at the counter’s input. The billing process ends. The data obtained are used in block 16 to calculate the period value by the formula (1). The q value is pre-entered.

Thus, the proposed method and device in comparison with the known can improve the accuracy by three times.

The increase in the accuracy of period measurement is due to the compensation of the period reference error on the leading edges of the signals, and the reference error on the trailing edges.

The introduction of new operations in the method and new elements with their connections in the device allows you to compensate for the error of measuring the signal period, * · due to the instability of the zero level, the signal amplitude. Using the proposed method and device, the requirements for the stability of the parameters of the input signals and the drift of the parameters of the circuit elements are reduced.

Claims (3)

The invention relates to a measurement technique and can be used, for example, in processing signals from photoelectric converters.  A known method for measuring the time interval ,. consisting in the input signal with a predetermined threshold level (1 curming at the moment when the signal crosses the pulse level of the beginning and end of the interval, counting the pulses of the reference frequency during the time limited by the pulses of the beginning and end of the interval H - This method has low accuracy due to the presence of an error (| adjustment of the pulses of the beginning and end of the interval due to the instability of the threshold level.  The closest to the invention according to the technical essence is a method of measuring the period of a quasi-harmonic signal by pulse quantizing the sample time interval between two nearest signal transitions through a fixed level, fixing after the intersection of the main level, the intersection points of the additional, increasing one after another, fixed levels, at the first intersection of each increasing level of the quantization frequency by the value of the reference frequency, decreasing repeatedly crossing each increasing frequency quantization level at the reference frequency value, counting the number of pulses varying quantization often-February 1. The disadvantage of this method is the low accuracy of the measurement period, due to the presence of measurement errors due to the instability of the zero level and the amplitude of the input signal.  The device closest to the technical essence of the invention is a digital infra-low-frequency periodometer containing a comparison circuit, a digital-to-analog converter, a counter, a control unit, two triggers, an exemplary frequency generator, a controlled frequency multiplier, a counting unit, and 3J keys.  The disadvantage of this device is the low accuracy of the period change due to the presence of a measurement error caused by the instability of the zero level and the amplitude of the input signal.  The purpose of the invention is to improve the measurement accuracy. period due to the exclusion of measurement error due to the instability of the zero level and the amplitude of the input signal.  This goal is achieved by the fact that, according to the method of measuring the signal period by quantizing an exemplary frequency of the time interval between the two nearest signal transitions through a fixed level, fixing after the intersection of the main level of intersection points of the additional increasing of the other fixed levels, increasing at the first intersection of each increasing level of quantization frequency by the value of exemplary frequency, simultaneously counting the number of quantization pulses the changing frequency, after fixing the crossing times of additional, increasing in succession levels, fixing the crossing times of additional, diminishing fixed levels, increasing the quantization frequency from zero to the sample frequency at the first crossing of each decreasing level, the intersection of each ascending level and the re-intersection of each descending level, simultaneously count the number of intersected level signals, the number of pulses and the reference frequency at time intervals between the time of crossing the upper main signal decreasing levels of intersection between the instants increasing and decreasing the upper levels, and their value determined period value.  Into a device consisting of a comparison unit, a digital-analog converter, a counter, a control unit, two triggers, an exemplary frequency generator, a counting unit, and a controllable frequency multiplier, whose input is connected to the output frequency generator, the input of which is connected to the output of the first trigger, installation input zero of which is connected to the output of the comparator unit and the summing input of the counter, the output of which code is connected to the first input of the comparator unit via a digital-to-analog converter, and the output of the transmission of the loan n with the counting input of the second trigger, the output of which is connected to the counting input of the first trigger, and the output of the controlled frequency multiplier is connected to the counting input of the counting unit, while the second input of the comparison unit is connected with the output of the control unit, three counting units are additionally added, the calculation unit , the comparison unit, the trigger and the one-shot, the output of which is connected to the control inputs of the main and first and second additional counting blocks, the first and second control inputs of the third additional counting block, and additionally The trigger is connected respectively to the outputs of the main and additional comparison blocks, the output of the additional comparison block is connected to the subtracting input of the counter, the loan output of which and two outputs of the additional trigger are connected to three corresponding inputs of the triggering of the odiovibrator, the output of which is connected to the input of the computation unit, information; the input inputs of which are connected to the outputs of the counting blocks, while the counting inputs of the second and third additional counting blocks are connected to the output of an exemplary frequency generator, with The electrical inputs of the first additional counting unit are connected to the output of the main and additional comparison units, the first input of the second comparison unit is connected to the output of the digital-to-analog converter, and its control input is connected to the output of the control unit, the output of the first additional counting unit associated with the controlled frequency multiplier .  FIG.  Figure 1 shows a timing diagram explaining the proposed method, where 1a is the input signal, which is equal to ceTky levels, 16 is the scale value, IB is the time interval separation pulses; in fig.  2, the functional scheme of the proposed device.  The essence of the method is as follows.  The intersection is fixed by the signal of the main level.  The base level is selected above the noise level accompanying the signal.  The time intervals are quantized by exemplary frequency pulses (when measuring dimensions, linear displacement sensor signals e can be used as pulses of the exemplary frequency), followed by the instant of intersection of the main level of the intersection time of additional, increasing one after another fixed levels (the distance between the levels is chosen greater than twice the amplitude of the noise superimposed on the signal).  At the first intersection of each age (in the whole level, the frequency of the KB quantization is increased by the value of the reference frequency (time interval 0-1, FIG. 1 Count the number of levels crossed by the signal a. .  .  The current result value can then be used to control the frequency increase factor.  The number of quantization pulses of a varying frequency a is counted.  and the number of quantization pulses of the model frequency in the time interval between the moments of the intersection of the upper and lower and higher levels, t.  e.  the value of ell is determined.  Following the fixation of the points of intersection of additional, increasing one after another levels, the points of intersection of additional, killed after each other ({n xsirovan levels) are recorded.  Each decreasing level corresponds to an increasing fixed level.  For example, the first decreasing corresponds to the penultimate increasing, the last decreasing, preceding the main one, corresponds to the first increasing one.  Thus, the total number of descending levels is one less than the number of ascending. When crossing each additional descending level, the quantization frequency is increased from zero to the model frequency value (time interval 1-2, FIG.  16) count the number of quantization pulses of varying and reference frequencies in the interval. the time between the intersection of the upper descending and the main level and the number of quantization of the reference frequency in the time interval between the intersection of the first back and second leading edge of the main level signal a (time interval 2-3, FIG.  1c).  The intersection of the main level by the si-channel is again recorded, followed by the intersection of the main level after the intersection of the additional, increasing one after another fixed levels.   With the repeated crossing of each increasing level, the quantization frequency is increased from zero to the value of the reference frequency (time interval 3-, FIG.  sixteen).  The number of levels crossed by the signal, the number of quantization pulses of the measuring and reference frequency e between the crossing of the main and upper diminishing level a and a, the number of quantization pulses of the reference frequency in the time interval between the crossing of the upper increasing and decreasing e levels are counted. ; fix the moments of repeated intersection of additional, decreasing one after another, xixed levels; from zero, the quantization frequency is increased by the value of the reference frequency at the intersection of each descending level (time interval k-S, FIG.  sixteen); The number of pulses of the quantizing and varying and reference frequencies is counted in the time interval between the intersection of the signal of the upper descending and basic levels a and a. .  The period value is determined by the formula -S.  zl-d44 aac).  Q% t Ca,)) 9) IT - where q is the ratio of the durations of the rear and leading edges of the signal.  In this case, the value is set according to a priori data with respect to the lengths of the front and rear edges of the ignal.  The device consists of blocks 1 and comparison, block 3 controls.  digital-to-analog converter C, counter 5, triggers 6 and 7, generator 8 of exemplary frequency, controllable multiplier 9 frequencies, blocks 10–13 cost estimates, trigger 14, odnovibrator 15 and block 16 calculations.  Comparison units 1 and 2 can be implemented as a series-connected adder, a threshold element, a level converter, logic elements, and a one-shot.  The controlled frequency multiplier 9 can be constructed either as a pulse-burst generator (the number of pulses in a burst is equal to the number whose code is set on the control-controlled frequency multiplier), or as a period divider of the input signals by a predetermined number.  The device works as follows.  At the initial time, the counter 5, the triggers 6, 7 and 14, the counting blocks 1013 are set to the zero state.  The voltage of the D / A converter is zero.  According to the signal from control unit 3, comparison units 1 and 2 are connected to the input of the device to which the measured signal is supplied.  Comparison levels are selected by the formulas with, Oex-Vn and and.  - and Cr where U and and are the levels of comparison of units 1 and 2 of comparison, respectively; and - values of the input voltage and voltage from the digital-analogue driver k; (f is the modulo quantum-analog converter k value. At Ug (T (basic level), comparison block 1 operates, the contents of counter 5 increase by unit, so the comparison levels shift to 2S and O, the content of block 10 increases to units, setting the controlled multiplier frequency factor equal to unity trigger 6 is set to one and enables the generator 8 exemplary frequency, the pulses from which are received in blocks 12 and 13 of the account and through controlled multiplier 9 frequency in block 11 eta.  When crossing the subsequent incremental levels, the multiplication factor increases, the counting unit 13 with each coincidence pulse zeros, thus, its contents correspond in the register output to the number of quantization pulses of the reference frequency calculated in the time interval from the penultimate to the last crossed levels.  When the unit 2 compares for the first time, which corresponds to the intersection of the upper descending level (Fig.  1, time 1) the contents of counter 5 is reduced by one, shifting down the comparison levels, trigger 14 switches, triggering one-shot 15 which zeroes counting blocks 10, 11 and 12, block 16 performs data exchange, while the numbers on the register outputs of counting blocks 10, 11 and 12 correspond to the number of crossed increasing levels a, the number of quantization pulses of increasing a, the fundamental frequency and j in the time interval between the first intersection of the signal of the main and upper descending levels and from the counting unit 13 - the number of quantization pulses ovnoy and frequency.  in the time interval between the upper ascending and descending levels.  After zeroing, a unit is recorded in counting unit 10, this is achieved by zeroing impulse generated by a single vibrator 15 on the leading edge of the pulse from comparison units 1 and 2, and the counting unit 10 increases its content by one on the back of the pulse from comparison units 1 and 2.  When the following levels intersect, the counting process repeats, when a loan appears at the output of counter 5, which corresponds to the contents of counter 5, equal to one, the one-shot 15 is triggered, wraps counting blocks 10, 11 and 12 and indicates the exchange of block 16 with them, thus getting values 2, h.  the trigger 7 is switched to the one state, the counter 5 is zeroed.  When the main level is re-crossed, the exchange and counting processes are repeated.  When the loan pulse reappears from the output of counter 5, trigger 7 switches to zero and flips trigger 9 6 to zero on the counting input.  The account counting process is 1.  The obtained data is used with in block 16 to calculate the value of the period by the formula (1).  The value of q is entered in advance.  Thus, the proposed method and device, as compared with the known ones, can increase accuracy by a factor of three.  The increase in the accuracy of the period measurement is due to the compensation of the error of the period reference on the leading edges of the signals, the error of the reference on the rear edges, the introduction of new operations in the method and new elements with their connections to the device allows to compensate for the measurement error of the signal period, due to the instability of the zero level , signal amplitudes.  With the proposed method and device, the requirements for the stability of the parameters of the input signals and the drift of the parameters of the circuit elements are reduced.  Claim 1.  A method for measuring the signal period by pulse quantizing an exemplary frequency of the time interval between the two nearest signal transitions through a fixed level of fixation, following the moment of intersection of the main level of intersection time additional fixed levels increasing one after another, increasing at the first intersection of each increasing level of quantization frequency by an exemplary frequency, simultaneously counting the number of quantization pulses of a varying frequency, characterized in that in order to improve the measurement accuracy, after fixing the crossing times of additional levels increasing one after another, the crossing times of additional levels decreasing one after another of fixed levels are increased, the quantization frequency is increased from zero to the sample frequency value at the first crossing of each decreasing level, re-crossing each ascending level and re-crossing each descending level, simultaneously count the number of crossed level signals, the number of impulses The quantization frequency of the model frequency in the time intervals between the moments of the signal crossing the main, upper descending levels, between the times of the upper ascending and descending levels, and the value of the period are determined from their value.  2  A device for measuring the signal period, consisting of a comparison unit, a digital-to-analog converter, a counter, a control unit, two triggers, an exemplary frequency generator, a counting unit and a controlled frequency multiplier, whose input is connected to the output frequency generator, the input of which is connected to the output of the first trigger, the zero input of which is connected to the output of the comparator unit and the summing input of the counter, the output of which is connected to the first input of the comparator through a digital-to-analog converter and the loan transfer output is connected to the counting input of the second trigger, the output of which is connected to the counting input of the first trigger, and the output of the controlled frequency multiplier is connected to the counting input of the counting unit, while the second input of the comparison unit is associated with the output of the control unit, that, in order to improve the measurement accuracy, it additionally introduced three counting blocks, a computing block, a comparison block, a trigger and a one-shot, the output of which is connected to the control inputs of the main and first and second additional blocks The first, second and second control inputs of the third additional counting block and additional trigger are connected respectively to the outputs of the main and additional comparison blocks, the output of the additional comparison block is connected to the counter subtracting input, the loan output of which is connected to the three corresponding trigger inputs one-shot, the output of which is connected to the input of the computing unit whose information inputs are connected to the outputs of the counting blocks, while the counting inputs of the second second and third additional counting blocks are connected to the output of an exemplary frequency generator, the counting inputs of the first additional counting block are connected to the output 93 of the main and auxiliary comparison block, the first input of the second comparison block is connected to the output of the D / A converter, and its control input is connected to the output of the control block , wherein the output of the first additional counting block is associated with a controllable frequency multiplier.  1 Sources of information taken into account during the examination 1. Yard Ting B.  AT. Kuznetsov L.  AND.  Radio measurements.  M. , Soviet Radio, 1978, p.  .   2. USSR author's certificate number 568902, cl. G 01 R 23/00, 1977. 3. USSR author's certificate number 47398 4, cl. G F 10/0, 1975. G t 3 FIGA 2