SU1723563A1 - Meter of transient characteristics - Google Patents

Abstract

The invention can be used to study and control the dynamic properties of controlled frequency devices and systems. The aim of the invention is to improve the accuracy and simplification of the device. Measuring transient characteristics contains: shapers 1,2,9 pulses, elements And 5,6. the trigger 7, the switch 10. The introduction of the delay elements 4.8, the memory block 11 makes it possible to increase the accuracy of the device and simplify it. 4.

Description

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The invention relates to radio measurements and can be used to study and control the dynamic properties of controlled frequency devices and systems, which include, for example, controlled quartz oscillators and radio engineering systems based on them.

Known gauge dynamic characteristics, containing the pulse shaper, frequency divider, synchronizer, recorder, switch, adder and differentiator.

The disadvantage of this technical solution is the low accuracy of restoring the function of the transient frequency setting process.

The closest in technical essence and the achieved effect is a transient response meter containing the first, second and third pulse shapers, N dividers, switching node, reset node, N RS flip-flops, N elements AND, two OR elements, serially connected switch and adder connected in series synchronizer and recorder, as well as two input and one output bus, which is connected to the output of the synchronizer, and the first input bus through the first pulse shaper is connected to the first inputs dividers, the output of the third pulse generator is connected to the input of the reset node and the first input of the switching node, the second input of which is connected to the output of the first pulse generator, each of the N outputs of the reset node is connected to the second input of the corresponding splitter and the first input of the corresponding RS trigger, the second the input of each RS-flip-flop is connected to the output of the corresponding divider, the first inputs of the AND elements are connected to the outputs of the corresponding RS-flip-flops and the corresponding inputs of the second OR element, the output of which through the second pulse shaper connected to the first input of the switch, the outputs of the elements And are each connected to the corresponding input of the first element OR whose output is connected to the second input of the switch, the output of the adder is connected to the second input of the recorder, the second input bus is connected to the input of the third pulse shaper, the output of the node The switch is connected to the second inputs of the elements I.

 The disadvantages of the known technical solution are the low accuracy of the measurements, due to the significant quantization error, as well as the complexity of its constructive implementation.

Consider an algorithm for converting a period or frequency deviation from a nominal value into a sequence of voltage readings using a known meter. It proceeds as follows.

At the same time from n0

the reference frequency pulses fo following the period To begin to form the polling interval tonp - Then, and from the fx impulses of the frequency under study fx following the period Tx, the interval studied is tx hxTx.

Form the measuring interval Ti PTHT - PoTo, which commutes the pulses of the reference frequency.

The number of switched pulses NK WTo (tx-t0) / T0 is converted into voltage Uwig, and each switched pulse corresponds to an increment of voltage per Lie quantization step, i.e. Uvih (tx-to) A U / That (PtTh - -ToTo1) -Li / To.

The accuracy of the measurement of the interval t, and is determined mainly by the quantization error. This error limits the resolution of the meter over the LTE period or the frequency Afp, which

determined by the obvious condition

Uvyh Uvyh AU and considering

Afp LTR | / (Tho 2 + Tr-LTR1) (1) is equal to Afp fxo / (tonp fo + T),

The complexity of the design implementation is due to the need to use multi-bit dividers with a variable division factor with the appropriate control schemes. So, for example, at tonp 1c, fo1-100 MHz, binary-decimal dividers with a variable division factor should have 32 bits.

The purpose of the invention is to increase accuracy and simplify the design.

The goal is achieved by improving the transient response meter, comprising three pulse drivers, two AND elements, a trigger, a switch, an indicator, a synchronizer, two input and one output buses, with the first and second input buses connected to the inputs of the first and second drivers pulses, the indicator sync input is connected to the synchronizer output and to the output bus.

Distinctive essential features of the transient meter are two delay elements and

the memory unit, the output of the first pulse generator is connected to the first inputs of the first and second And elements, the output of the second pulse shaper is connected to the second input of the first element And, and through the first delay element to the second input of the second element And, the output connected to the R input of the trigger, The S input of which is connected to the output of the first element I and to the counting input of the switch, the inverse output of the trigger is connected to the input of the third pulse generator, the output of which is connected to the control input of the memory unit and through the second The delay element is connected to the switch installation input, and the switch output is connected to the information input of the memory unit connected to the information input of the indicator.

The applicant did not find technical solutions that have similar features with features that distinguish the proposed solution from the prototype, and, therefore, the proposed technical solution has significant differences.

To prove the achievement of the objective of the invention, consider the process of converting a period or frequency deviation from a nominal value into a sequence of voltage readings, which proceeds as follows.

From the pulses of the studied frequency fx form a sequence of the studied pulses of a calibrated duration of Ti (fig.Cha).

Of the reference frequency pulses fo. the value of which must satisfy the condition

f0 fxo + Afy, (2)

where fxo is the nominal (initial) value of the frequency under study;

/ Afy - the required value of the averaging frequency,

form a sequence of reference pulses of a calibrated duration T0 (figv). . ... - ..

Logical multiplication of the formed sequences of the studied and reference pulses is carried out. As a result of this and under the condition

(Go + p) A T. (3)

where A T (Tx-To) (fo-fx) / fxfo is the difference in the follow-up periods of the studied Tx and reference T0 pulses, a packet of coincidence pulses are formed (Fig. 1c). The number of pulses in a packet is determined by the ratio. N (r0 + n) - fx -foAfo-fx). (four)

Let the frequency under investigation vary according to the law

fx fxo ± Afx, (5)

where Afx is the frequency deviation to be measured, then expression (4) with regard to (2), (5) is converted to

N (ha. + N) (fxo ± Afx) (fxo + Afy) / / (Afy ± Afx). (6)

Transient meters to increase their resolution are usually used with frequency comparators, for example, type 47-12, the output frequency of which has a standard value of 1 MHz. The required frequencies of averaging do not exceed tens of hundreds of hertz, i.e. it can be argued that fxo afx. fxo afy.

Therefore, in order to simplify the mathematical calculations, the expression (6) is represented as

N (G0 + P) fxb / (Afy + Afx), (7)

20

from where

Afy ± Afx (r0 + ri) -fxo2 / N, (8)

or

Iw-uo / n,

(9)

Where

Willow K (Afy ± Afx); U0 K v (r0 -Lp) -fxo2; K-coefficient of proportionality, taking into account the conversion of frequency deviation to voltage.

To compare the metrological characteristics of the prototype and the gauge in question, let us evaluate the main components of the error of the latter; errors due to quantization, noise at the input, instabilities of the reference frequency, durations of calibrated pulses, thresholds of drivers, and characteristics of signals arriving at their inputs. The measurement error of the transient is estimated by its single implementation. Therefore, this error is defined as the sum of the maximum values of all components.

Consider these components. 1. The error of quantization. It is due to the random nature of the location of the leading edge of the pulse of the measured frequency relative to the leading edge of the pulse of the reference frequency and, as with any digital device, is equal to

DMQ ± 1. (S)

The absolute value of the quantization error in frequency is found from the condition

N, which in view of (5), (7) is equal to

(r0 + n) -fL + Afy. (11) 2. Error due to interference at the input. It arises due to the spread due to the interference of the Ate trigger points.

threshold device in the formation of pulses of a calibrated duration and can be written as

Ate-DC, 1 / (2 V5.jr-f .. U), v where AUn1 is the noise voltage at the input of the meter.

During the lifetime of the coincidence packet, the center of each of the pulses of the packet moves uniformly with respect to the centers, for example, the calibrated pulses of the frequency under investigation, in increments of r / N G0 A tu / (m + P) fxo2, (12)

Therefore, the error due to noise at the input, expressed in code, can be written as

Lm - At {-) -fxo v. AN - -2vT .f tb-Afy-X

Yes

U

(13)

As a source of reference frequency using a standard or frequency synthesizer, therefore, it can be argued that

A Un / U x D Unl / U o and, therefore,

. . (14)

3. Error due to short-term frequency instability. During the measurement process, the reference frequency is considered constant, so any change in it leads to an error in the measurement of the frequency under study. This error can be written as

D Max and f0 / A fp and f0 (r0 + TI) X

xfxoz + afyl / afy i

(15)

where a is the relative value of short-term frequency instability.

4. Error due to instability durations of calibrated pulses. It is due to the change in the duration of the calibrated pulses in the measurement process and is equal to

A N (оо г0 + а n) / 0 (OQ г0 + «1 п) х

x (To + P). THO / (Go Afy), (16)

where Oa, a is the relative value of the instability of the durations of the reference and test pulses, respectively.

5. The error due to the stability of the thresholds and the characteristics of the input signal. The trigger time of the threshold device tcp is determined from the condition

Un Um sin (2 L: f tcp). where Un is the nominal value of the tripping voltage;

Um is the maximum value of the input voltage, and is equal to

tcp arcsin (Un / Um) / (2 tgg), and its maximum instability is Atcp (AUn + Un -AUm / Urn) /

/ (2ttfVUm2-Un2).

This error, expressed in code, is equal to

DMS-AJЈ

(T0 + P) -fxo

6

X

ajrfroAfy.Vu.u

x (di +

Un -AUmx Um}

(17)

five

Since A Umx A Umo, since frequency stabilization is impossible without amplitude stabilization, we can assume that DMh. (18)

0. We will evaluate all the components of the error on a specific example.

Let T0 TI f0 1001000 Hz; fxo 1,000,000 Hz; Afy 1000 Hz; Deep / and Yu 4; “1 10 3; Un B; Um 2B; AUm 102

Oo 10

v3

-10 3; a 10 8;

5-0.005 V; AUn .10 V.

Then in accordance with (13) - (18) ANnx

0.2; D McNich 2. A Ntf 0.2; D MCh 0.15.

An analysis of the results obtained shows that the quantization error significantly exceeds the other components, which, in addition, can be reduced by stricter requirements for the parameters of input signals and individual meter nodes. Therefore, we can assume that the resolution of the meter basically limits the quantization error.

Comparison of the calculation results for the co-relations (1) and (11) shows that, all other things being equal, the proposed meter has a 20 times higher resolution (for f0 10 MHz, i.e., when constructing meters, for example,

5 chips 155 series).

Thus, in the inventive meter, the period or frequency deviation from the nominal value is converted into a sequence of voltage readings.

0 (Fig. Tr, Fig. 4), following with a predetermined averaging frequency. Increased accuracy is achieved by increasing the resolution.

Figure 1 shows time diagrams explaining the process of converting a period or frequency deviation into a sequence of voltage readings; figure 2 shows the functional diagram of the claimed meter; on fig.Z shows the functional diagram of the DAC; figure 4

shows the restored time function of the frequency transition process.

The transient response meter contains the first 1 and second 2 pulse shapers, the synchronizer 3, the first delay element 4, the first 5 and the second b elements I. trigger 7, the second delay element 8, the third driver 9 pulses, switch 10, memory block 11, indicator 12, the first 13 and the second 14 input tires and the output bus 15.

In the proposed meter elements are connected as follows.

The output of the second pulse driver 2 is connected to the input of the first delay element 4 and to the second input of the first element 5, the first input of which is connected to the output of the first pulse generator 1 and to the first input of the second element 6, the second input of which is connected to the output of the first delay element 4 , S- and R-inputs of the trigger 7 are connected to the outputs of the first 5 and second 6 elements, respectively; And the input of the second delay element 8 is connected to the output of the third pulse generator 9; the inverse output of the trigger 7 is connected to the input of the third form The puller 9 pulses, the counting input and the installation input of the switch 10 are connected to the outputs of the first element 5 and the second delay element 8 respectively, the control and information inputs of the memory unit 11 are connected to the outputs of the third pulse generator 9 and the switch 10 respectively, the control and information the indicator 1.2 inputs are connected to the outputs of the synchronizer 3 and the memory block 11, the first 13 and the second 14 input buses are connected to the inputs of the first 1 and second 2 pulse formers, and the output bus, respectively 15 connected to the output 3 of the synchronizer.

Indicator 12, as an option, contains a digital-to-analog converter (D / A converter) 16 and an oscilloscope 17.

The DAC 16 (FIG. 3) contains a zener diode 18, resistors 19-21, field effect transistors 22, an operational amplifier 23, and a resistor 24.

The proposed gauge of transient characteristics works as follows.

Before starting the measurements, they are calculated taking into account the relation (3) of the duration of the calibrated pulses of the test and reference frequencies. Adjust on these durations, respectively, the first 1 and second 2 pulse shapers. The value of the reference frequency must satisfy the value calculated by expression (2). The time delays of the first 4 t3i and second 8 t32 delay elements should satisfy the following relations:

5Х31 “That / 2; T32 "(1,5-2) -Tzap,

where taan is the time of recording information in memory block 11.

The pulses of the investigated fx and the reference f0 frequency of the first 13 and second 14 input tires

0 arrive at the inputs of the first 1 and second 2 pulse shapers, respectively. At the outputs of the latter, sequences of the studied pulses of calibrated duration ri (Fig. La) are formed.

5 reference pulses of calibrated duration T0 (Fig. 1c), respectively. These sequences are fed to the inputs of the first element AND 5, at the output of which the main pulse packets are formed.

0 matches (figLo1). The number of pulses in a packet is 7, it is counted by switch 10 (Fig. 1d, n).

The sequence of reference pulses is delayed by a time interval.

5 Tet (Fig. 1c) and, together with the sequence of the pulses under study, are fed to the second element 6. At the output of the latter, auxiliary packets of coincidence pulses are formed, which are delayed

0 relative to the respective main packets in the time interval 1/2 Afy (Fig. 1e). According to the first impulses of the main packets, the trigger 7 is set to one state, according to the first impulses

5 auxiliary packages - in zero. The third driver 9 pulses on the leading edge of the signal at the inverse output of the trigger 7 forms a short pulse (Fig. 11), which rewrites in

0, the memory block 11 information from the output of the switch 10 and, at a time interval t32, sets the latter to the initial state. Further, the switch 10 counts the number of pulses in the next

5 main packet matches.

Information from the output of the memory block 11 is supplied to the indicator 12 for visualization (Fig. Chd),

The synchronizer 3 synchronizes the start of operation of the meter with the time required to apply a test action on the object under study.

The work of individual complex nodes meter.

5 First 1 and second 2 pulse shapers.

These pulse shapers can be built on frequency multipliers, followed by extracting a certain

the number of periods of the studied or reference frequency. In this case, the instability of the pulse duration of the frequency fo is determined mainly by the short-term frequency instability of the reference source. And the instability of the pulse duration of the frequency fx will not be more, since when using a frequency comparator, such as type 47-12, the deviation at its frequency output from the nominal value equal to 1,000,000 Hz should not exceed 1000 Hz. (E32.721.10710. Frequency comparator 47-12. Technical description and operating instructions).

DAC 16.

Resistor 19 and zener diode 18 provide the value of Oo (9), the controlled divider consisting of resistors 20 and RJ; (resistors 21 and field-effect transistors 22) form the required law for changing the output voltage. So, when a high potential is present at one of the second inputs, the corresponding field-effect transistor: resistor 22 is open and the resistor is connected to the common bus. At low potential, the transistor 22 is closed and the resistor is disconnected. And if the ratings of the resistors connected to the common bus, correspond to the number of R / 20, R / 21, R / 22. ..., R / 2n, then the state of the second inputs can be considered as a binary number. In this case

R "

one

2 ° / R + 21 / R –Ь + ... + 2n / R R R

2 ° + 21 + 22-f. .. + 2 NBX

where Nex is the binary number that comes in at the input of the DAC 16.

The transmission coefficient of the controlled divider connected to the non-inverting input of the operational amplifier 23 is equal to

. KM R / (R +) -1 / (1+ Nex), A voltage repeater is assembled at the operational amplifier 23 and resistor 24, eliminating the influence of the input circuits of the oscilloscope 17 on the gain ratio of the controlled divider. The output voltage of the DAC 16 is equal to

Willows Ki-io i0 / (1 + NBX). (19)

And if the input code of the D / A converter 16 is equal to Nex M-1, which is ensured, for example, by setting the output pulse of the second element 8 of the switch delay 10 V

unit state at the outputs, then the expression (19) corresponds to the required one (9).

Compared with the prototype, the claimed transient response meter has the following advantages:

a higher accuracy due to an increase in the resolution of the meter, the latter, with the same resolution requirements, allows one to obtain a greater number of voltage readings in the transient frequency setting section:

simplified constructive implementation, due to the lack of

multi-digit divider with

appropriate control schemes.

The proposed meter frequency transient characteristics can be used in automated systems

and complexes for testing controlled quartz oscillators and radio engineering systems based on them, as well as autonomously and as a measuring device. Formula inventions

A transient response meter comprising first, second, and third pulse drivers, first and second, AND elements, trigger, synchronizer, indicator, switch, characterized in

that, in order to increase the accuracy and simplify the device, the first and second delay elements, the memory block, the output of the first driver are connected to the first inputs of the first and second elements I. The output of the second driver is connected to the second input of the first element I. the delay element - with the second input of the second element And, the output of which is connected to the reset input of the trigger, the installation input of which is connected to the output of the first element And and the counting input of the switch; the inverse output of the trigger is connected through the third form The pulse generator with the control input of the memory unit, and through the second delay element - with the installation input of the switch, the output of which is connected to the information input of the indicator, the output of the synchronizer is connected to the input of the indicator.

p p p p p p

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  Ch In. L

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Claims (1)

Claim The transient response meter containing the first, second and third pulse shapers, the first and second, AND elements, trigger, synchronizer, indicator, switch, characterized in that, in order to improve accuracy and simplify the device, the first and second delay elements are introduced into it, a memory unit, the output of the first driver is connected to the first inputs of the first and second elements And, the output of the second driver is connected to the second input of the first element And, and through the first delay element to the second input of the second element And, the output to otorogo connected to the trigger reset input, the installation input of which is connected to the output of the first element And and the counting input of the switch, the inverse trigger output is connected through the third pulse shaper to the control input of the memory unit, and through the second delay element to the installation input of the switch, the output of which is connected to the information indicator input, the synchronizer output is connected to the indicator input. 1723563