SU1269153A2 - Method of checking time non-symmetry of volute - Google Patents

Abstract

The invention relates to measuring technique and is complementary to the author. St. No. 817619. The purpose of the invention is to expand the functionality of, p,.:,. ..., J 1C, i /. way. The device implementing the method contains comparators 1 and 2, sources, sources 3 and 4 of reference levels, adder 5, mixer 6, tunable local oscillator 7, intermediate frequency filters 8, 9 and 10, detectors 1113, voltage dividers 14 and 15 gauges 16 and 17 voltages. By forming a sequence of pairs of pulses corresponding to. the duration of the fronts of the meander, the multi-frequency conversion of this sequence, the selection of the 1st harmonic and the measurement of its amplitude it is possible to determine the asymmetry f of the duration of the fronts of the meander, which is proportional to the amplitude of the i-th harmonic. 2 Il. N Od ate with MS)

Description

The invention relates to a measurement technique, can be used to control the temporal asymmetry of the half-waves of the meander by the pulse duration and the duration of 5 fronts and is an improvement of the method according to ed. St. No. 817619.

The purpose of the invention is to expand the functionality of the method by providing control of the asymmetry of the duration of the meander fronts.

In FIG. 1 is a diagram of a device that implements the method ', in FIG. 2 is a timing chart explaining a method. fifteen

The device (Fig. 1) contains the first 1 and second 2 comparators, the first 3 and second 4 sources of reference levels, an adder 5, a mixer 6, a tunable local oscillator 7, the first 8, the second 20 swarm 9, the third 10 filters of intermediate frequencies, the first 11 , second 12 and third 13 detectors, first 14 and second) ROY 15 voltage dividers, first 16 and second 17 voltage meters. 25

The essence of the method is as follows. · ·

In addition to the temporal asymmetry of the meander, the asymmetry ψ of the duration of its fronts is also subject to control. zo

Moreover, by definition, it is considered that the quantity φ is equal to

Ч> = <*, (1) ^L 1 where is the duration of the leading edge of the meander pulse; the difference in the durations of the trailing and leading edges, the meander impulse. 49

To determine the value of ψ from the sequence of pulses of the meander (Fig. '2), a sequence of pairs of pulses is formed, the duration of the first of the pulses of the pair being 45 by, and the duration of the' second Τ ', + + δϊ ₄ , the interval between the pulses of the pair is equal to the pulse duration t meander.

It is known that the Lap-j ₀ las image of a sequence of two rectangular pulses is

U (p) = [1 - e ' ^P1 ' + ε ~ ^ρΐ (1 _ _f (2) ⁵⁵ where E is the pulse amplitude, * p is the Laplace operator.

Obviously

U (p) = ~ I ¹ “ ^{e + e} ' ^{A +} + _e - ^p7 ') + e- ^w ^ (1 -. (3)

After substituting p = j we get \ U (jb)) (= - ^ 2sin -j-sin sin-T, - + _{+ -} sin- (4)

To determine the amplitude of the nth harmonic, we substitute in expression (4) ц) ’= 2Pn / T and we obtain

U (n)

2nd year nTL. rtJrt

- [sin y.sin-n-GT / C, t sm —— J · (5)

In the other case, if in relation (5) we choose n = i:

(6) taking into account the fact that with the meander Τ = 2ΐ, the first term in brackets becomes zero, since sin 23Г = 0, and the expression is converted to

For small values, we obtain (7)

U (i) ^ (8)

those. the amplitude of the i-th harmonic is proportional to the value of Ch>

A device that implements the method (Fig. 1), works as follows.

To control the asymmetry of the length of the meander, a comparator 1 is used, while a reference level is applied to it from source 3 (Fig. 2). The reference level U ' _W2 is supplied to the comparator 2 from the source 4, which is larger than the meander pulse amplitude, which will lead to its exclusion from the operation of the device. In this case, using the comparator 1, adder 5, mixer 6, local oscillator 7, filters 8 and 9, detectors 11 and 1'2, divider 14 and meter 16, the asymmetry of the meander duration is determined by a known method.

To control the asymmetry φ of the duration of the meander fronts on the comparator

1269 from source 3, the level Uy _Pj is supplied, and to the comparator 2 from source 4, the level U _7f2 . When the voltage Uc at the output of the comparator 1 U _t > U _VP1, it generates a positive voltage jump h. When the voltage U _t at the input of the comparator 2 U _t > υ _{ΎΡ 2} it produces a negative voltage jump. As a result of summing up the positive and negative 10 jumps in the adder 5, a sequence of pairs of pulses is formed at its output (Fig. 2).

In mixer 6, the pulse signal is subjected to multi-frequency conversion 15 with a simultaneous decrease in frequency by the frequency f _{r of} local oscillator 7. As a result of multi-frequency conversion, a frequency spectrum is formed at the output of the mixer, among which 20 there are frequencies fi = ft - fr »fj = 2 (f _t - f _r ), = i (f _t - f _r ), (9) ₂₅ where f _t is the frequency of the first harmonic.

The frequency f _{3 is} proportional to the frequency of the ith harmonic, the amplitude of which determines the asymmetry μ> the duration of the meander fronts. _thirty

Using the filter 10 of the intermediate frequency, the frequency f _{3 is} tuned, using the detector 13, the harmonic amplitude is converted to a constant voltage and fed to the input of the meter 17, which determines the difference in the amplitudes of the signals supplied to its inputs. At the other input of the meter 17 receives a constant voltage proportional to the amplitude of the first _{40 ;} harmonics highlighted by the filter 8 and the detector 11. The divider 15 provides the ability to adjust the coefficient. coefficient <x of proportionality and setting the meter 17 to zero under the condition of complete symmetry of the durations of the meander fronts, i.e. when the asymmetry is normal. If ve. M> is greater than or less than the norm, meter 17 gives, respectively.

153 positive or negative readings.

Thus, due to the formation of a sequence of pairs of pulses corresponding, according to the duration of the meander fronts, to the multi-frequency transformation of this sequence, the allocation of the frequency of the ith harmonic and the measurement of its amplitude, it is possible to determine the quantity φ, since it is proportional to the amplitude of the ith harmonic. This extends the functionality of the method relative to the known method, where the 'value m> cannot be determined.

Claims (1)

The invention relates to instrumentation technology, can be used to control the time asymmetry of the half-wave of the meander over the pulse duration and the duration of the fronts and is an improvement of the method according to the author. St. No. 817619. The purpose of the invention is the expansion of the function; the ionic capabilities of the method by ensuring control of the asymmetry of the duration of the meander fronts. FIG. 1 shows a diagram of a device implementing the method; in fig. 2 is the temporary diame ima, explaining the method. The device (Fig. 1) contains first 1 and second 2 comparators, the first 3 and second 4 sources of reference levels, adder 5, mixer 6, switchable local oscillator 7, first 8, second 9, third 10 industrial filters (each frequency, the first 11, the second 12 and the third 13 detectors, the first 14 and the second (Roy 15 voltage dividers, the first 16 and second 17 voltage meters) The essence of the method is as follows. Besides the time asymmetry of the meander, the asymmetry C of the duration of its fronts is also monitored. By definition, this value is considered to be equal to VP 1 ti gd e 1 is the duration of the front edge of the pulse MeaH; i, pai is the difference of the durations of the rear and front edges of the square wave pulse. To determine the value of J from the sequence of square wave pulses (Fig. 2), a sequence of pairs of pulses is formed, and the duration of the first pulse of the pair is ti, and the duration of the second tj + + 4tj, the interval between the pulses of the pair is equal to the pulse duration of the meander. It is known that the Laplace image of a sequence of two rectangular pulses is and (p) i 1 - + e- (1 - where E is the pulse amplitude, p - opera Laplace op obvious and (p) - 1 - s + e + n (1 -. (3) After the substitution of p j, we get. 2sin, sin i | 2: + U (ju)) Е. u) At + -r- Sin - ;: tO 2 To determine the amplitude of the nth harmonic, we substitute 2THP / T into the expression (4) and we get, t / h 2Eg. tm, U (n). niTXT-i + sin; In that case, if in the relation (5) we choose n L: taking into account the fact that when the meander, the first term in the brackets turns to zero, since sin 2EG O and the ff converts to the form u (i) 4t-and J- Ji.a.ti, .-, 4 Ti TTJ For small values. semi2E AtTt and (1) 1g, i.e. the amplitude of the 1st harmonic is proportional to the value of H. The device that implements the method (Fig. 1) works as follows. To control the asymmetry of the meander duration, a comparator 1 is used, while a source is supplied to it from the source 3, which is the reference level (Fig. 2). The comparator 2 from source 4 is supplied with a reference level uvpj, a larger amplitude of the meander pulse, which leads to its exclusion from the operation of the device. In this case, using the comparator 1, the adder 5, the mixer b, the local oscillator 7, the filters 8 and 9, the detectors 11 and 12, the divider 14 and the meter 16, the asymmetry of the meander duration is determined by a known method. To control the asymmetry φ of the duration of the edges of the meander, the comparator 3 1 from source 3 is supplied with the level Uypj, and the comparator 2 from source 4 with the level Uv, p. With a voltage U at the output of the comparator 1 U U, it produces a positive voltage jump. When U is applied to input voltage (2 UU generator, it produces a negative voltage jump. As a result of positive and negative jumps in the adder 5, a sequence of pairs of pulses is formed at its output (Fig. 2). In the mixer 6, the pulse signal is subjected to multi-frequency conversion with a simultaneous decrease in frequency by the magnitude of the frequency f, is heterodyne 7. As a result of a multi-frequency conversion, a spectrum of frequencies is formed at the output of the mixture of bodies, and there are frequencies among them. f 1 fc - fg, f, 2 (f, - f,) fi (f, - f,), (9) where fj, - frequency of the first harmonic. The frequency fj is proportional to the frequency of the I and harmonics, the amplitude of which determines the asymmetry η duration of the square of the square wave. Using the intermediate frequency filter 10, sets the frequency f, the detector 13 converts the amplitude of the harmonic f to a constant voltage and serves To the input of the meter 17, which determines the difference of the amplitudes of the signals arriving at its inputs. To the other input of the meter 17 there is a constant voltage, proportional to the amplitude of the first harmonic f of the filter 8 and the detector 11, Divider 15 provides the ability to adjust the coefficient of proportionality (X of proportionality and the installation of the gauge 17 to zero under the condition of full symmetry of the length of the edges of the meander, i.e. when asymmetry is normal. If the value of H is more or less than the norm, the meter 17 gives, respectively. 534 positive or negative readings. Thus, due to the formation of a sequence of pairs of pulses corresponding to the duration of the fronts of the meander, the multifrequency transformation of this sequence, the allocation of the frequency of the harmonic and the measurement of its amplitude, it is possible to determine the value of C), since it is proportional to the amplitude of the ith harmonic. This extends the functionality of the method with respect to the known method, where the value of C) cannot be determined. Formula invented and Method of control of the time asymmetry of the meander by auth.St. No. 817619, characterized in that, in order to expand the functionality of the method by providing control. Asymmetry of the duration of the edges of the meander, a sequence of square amplitude pulses of a fixed amplitude coinciding in time and proportional to the duration of the front and back edges of the meander pulse is formed from the controlled square wave decomposition of the formed sequence of pairs of pulses into harmonic components, extract from the frequency spectrum the harmonic of alternating voltage with i 2t / ,, where t is the pulse repetition period in a sequence of pulse pairs, Il is the length of the leading edge of the square wave pulse, and converts the resulting alternating voltage into a constant, extracts the first harmonic of the alternating voltage from the frequency spectrum, converts the resulting alternating voltage constant voltage and weaken the constant voltage, subtract the resulting constant voltage from a constant voltage proportional to the amplitude of the i-th harmonic, and judging by the magnitude of the difference obtained, the asymmetry duration and the fronts of the meander. ilP, UR% y / v fig.g