SU742829A1 - Meter of transient process time of frequency stabilizing - Google Patents

Description

The invention relates to a technique for automatically measuring the dinaltic parameters of various objects and can be used for. measuring the transient time of signals with pulse frequency modulation. A device for measuring the time of a transient process of setting a frequency is known, which contains a reversible counter, the inputs of which are connected to the sources of the test and reference frequencies through the first and second keys and corresponding drivers, and the output device is connected to the trigger input controlling the first and second keys. , a comparison device with a source of south voltage reference voltage at one input and a digital clock, the input of which is connected to the output of the comparison device, the second input of which is through the device averaging connected to the output of latch 1 disadvantage of this device is the low accuracy of measurement of the ambiguity reference end time transient. The purpose of the invention is to improve the measurement accuracy of short-term initial frequency setting processes by averaging sequentially obtained measurement results. For this purpose, a second averaging device, a recorder and a control unit, the two outputs of which are connected respectively to the inputs of the zero setting, are introduced into the proposed transient time setting meter. trigger units, and its two inputs are connected respectively to the control inputs of the first and second terminals, the third input of the control unit is connected to the output of the reversing counter, and its fourth input is connected to the input of the starting pulse of the digital clock, the output of which is through the second averaging device connected to the input of the recorder. FIG. 1 shows a block diagram of the proposed device; in fig. 2 is a timing diagram of the operation of a known meter during a short-term aperiodic transient process, the establishment time of which is several periods of the frequency under study; in fig. 3 - a similar timing diagram for the proposed meter; in fig. 4 - times on the diagram characterizing the dependence of the measurement error on the delay time of the starting pulse. The device contains signal conditioners 1 and 2 of the measured reference frequency, the first 3 and second 4 keys, reversing meter 5 ,; trigger b, first averaging device 7, comparing element 8, digital clock 9, adjustable-reference source 10, control unit 11, averaging device 12 and registerr 13. The known meter provides the necessary accuracy of measuring the time of the transition process of setting the frequency at monotonous dependence of time of establishment and considerable duration. In this case, the measurement error is not dependent on the initial state of the trigger. After the power is supplied, the initial state of the trigger can be arbitrary, but further with it is subject to rigid logic. However, by the time of the subsequent measurements, the state of the trigger will again be arbitrary, which affects the error from the 1 | 1 of the fast-paced transition processes of frequency setting by a known meter. : Based on what was said with FIG. ; FIG. 2a shows the aperiodic final input signal process in FIG. 2b is a transient process for setting the frequency under study in FIG. 2c - pulses of reference frequency s fgy; in fig. 2d is a signal at the output d: trigger b, if the pulse counting starts at the frequency f. 2d is the signal at the output of the trigger, if the counting of pulses with a reversing switch 5 starts from the reference frequency f with the number of pulses per. equal to two; in fig. 2e and - the result of measuring the duration of the transient process for the two following one another cases of measurement in the first case, starting with the measurement of the frequency under investigation, and so of the second reference frequency; in FIG. 2 ff, the start of the incoming - pulse digital clock. From FIG. 2e, g, it can be seen that for two logical states of the trigger there are two different results of measuring the time of the transient frequency setting process. When measuring short-term transient processes, the known meter gives a significant error. In the proposed gauge, the accuracy and ekureniya is increased due to the averaging of the obtained time intervals (see Fig. 2e and g). The proposed meter works as follows. The investigated frequency of the transient establishment, which needs to be measured, is fed through shaper 1 and key 3 to the input of the reversible counter 5, to the input of which the reference frequency fg also goes through shaper 2 and key 4. Keys 3 and 4 are controlled by different outputs of trigger 6. At an arbitrary time, only one of the keys 3 or 4 will be opened, depending on the level of the trigger output signal 6. The latter changes its state when it arrives. To it: the even input of the overflow pulse from the output of the reset counter Single 5 or on arrival at its separate input signals from the outputs of the control unit II. Depending on the initial state of the trigger 6 reversing counter 5, read T every time before its overflow, either the pulses of the frequency under study or the pulses of the reference frequency. As a result, the output of the trigger 6 forms a sequence of pulse-width modulated pulses, the duration of which depends on the frequency under study, and the time intervals between them are constant and determined by the constant of the reference frequency. After averaging the sequence of pulse-width modulated pulses at the output of the averaging device 7, a constant voltage is obtained, the value of which unambiguously depends on their frequency under study. With a monotonic change in the frequency under study, the value of this voltage also monotonously changes. When the frequency under study reaches a predetermined value corresponding to the end of the transient establishment time, the voltage at the output of the averaging device 7 reaches the corresponding level of the reference voltage source 10. After that, the comparison element 8 is triggered and outputs a stop pulse to the digital clock 9 and the control unit 11, enabling the flip trigger b to a state opposite to the original. The digital clock starts at the moment of the beginning of the transient process, therefore, after the arrival of the stop pulse, they stop, issuing to the averaging device 12 a pulse of the duration of the transient frequency setting, which is recorded by the recorder 13. Before starting the measurement, the control unit 11 analyzes the state of you; trigger trigger levels 6 The first overshoot pulse from the output of the reversible counter 5 prohibits the control unit 11 from analyzing the state of the trigger 6. At this, the initial state three is remembered in the control unit 11 .gera 6 is prepared and the team on his transfer. The command is executed after the arrival of the resolution impulse from the output of the comparison element 8 after the end of the first cycle of measuring the transient time. After the flip-flop of the trigger 6 to the state opposite to the initial one, the meter is ready for the next measurement cycle set by the starting pulse at the input of the digital clock 9.

The measurements are carried out alternately, starting either with the frequency fx or with the frequency f37, excluding the non-oddness of the timing of the end of the transient frequency setting. At the output of the averaging device 12, information is accumulated on the average value of the transition process over all measurement cycles, which is recorded by the recorder 13.

The accuracy of the measurement can be improved if the reversible counter 5 is performed with an adjustable overflow, in which case the time measurement (No transient is carried out similarly for each overflow value.

When measuring, the value of the reference frequency can be lower or higher than the predetermined steady-state value of the studied frequency, from different frequency sensors. In this case, in order not to tune the source of the reference frequency, it is possible to make the adjustment of the reference level of the source of the reference voltage 10, by graduating it with the adjustment body in the frequency values. Then the adjustment of the meter when changing the frequency sensors: is reduced only to turning the knob to a predetermined mark on the adjusting organ of the source of the reference voltage 10.

The operation of the device is explained by the timing diagrams shown in FIG. 3

FIG. Over shows the transition curve; in fig. 36 — transient npduecc setting the frequency under study fX; in fig. Zv - pulses of the reference frequency fg -, -; in fig. Zr is the signal at the trigger output, if the counting of pulses by a reversible counter; 5 begins with the frequency under study in FIG. Back - the signal at the trigger output, if the counting of pulses with a reversible counter begins with this frequency of FIG. Ze and g are the first {interim for the proposed meter the measurement result of the duration, the transition; the process of setting the frequency for two successive measurements: in the first case, starting from the moment of measuring the frequency under investigation, and in the second reference frequency from the output of digital hours 9; in fig. 3 and the starting one (pulse arriving at the control unit of the digital clock 9; in FIG. 3, the final average result of measuring the duration of the transient process of setting the frequency at the output of the second averaging device 12.

The sleep of FIG. 2 and 3, the reverse transition process is not shown).

From the comparison of the timing of the operation in FIG. 2 and 3, it can be seen that by the moment of starting the starting impulse, trigger b can be in one of two logical states x

(see Fig. 2d, d and 3g, d).

ABOUT

and

If by the moment of the pulse start the trigger 6 is in the position Ч, then the counting of the pulses by the reversible counter 5 starts from the frequency f studied (see fig. 26 and 3b). The signal at the output of the trigger 6 corresponds to the diagrams in fig. 2g and 3g and the duration of the transient process measured by digital clock 9 corresponds to the point t in FIG. 2nd and Ze.

If the trigger b is in the O position at the moment when the starting pulse is applied, then the counting of the pulses by the reversible counter 5 will start from the reference frequency fg-r (see Fig. 2c and Sv). At the same time, the signals at the output of the trigger 6 correspond to plots 2d and Back, and the transition time measured by digital clock 9 corresponds to the point t, (see Fig. 2g and Зж).

From the foregoing it is clear that for two logical states of a trigger two different results of measuring the time of the transient process of establishing the frequency are obtained, commensurate with several periods of the frequency under investigation, both when measured by the known and proposed measures. However, for a known meter, the measurement result is t. or t.j is the final result, and for the proposed, intermediate measurement results, which are then averaged by the second averaging device 12. The final result of the measurement of the time-to-frequency frequency transient process is shown in FIG. Зз.

The measurement error largely depends on the synchronization of the starting pulse with the logic levels of setting the initial position of the trigger and with the pulses of the test frequency.

In the proposed meter start-. A pulse is generated only after the trigger is set to the proper state, the registration of the transient duration of the JTOPOM 13 register and the end of the reverse transient is completed. This eliminates the element of randomness in the selection of the initial state of the trigger and solves the problem of the temporal location of star-. of the pulse with a logic level

Toi setting the initial position of the trigger.

In the proposed meter, the starting pulse feed is synchronized by the leading edge of the pulses of the frequency under investigation with an adjustable delay, i.e. synchronization on the leading edge is carried out with a shift by the value of t / h after two measurements, where TG is the synchronization delay time

n is the number of pairs of measurements. The time period C should be several times less than the period of the frequency under study and should be determined from the specific conditions of the circuit realization of the source of the starting pulse (not shown in Fig. 1)

| The dependence of the measurement error on the synchronization delay belt is shown | ano in FIG. four.

Figures 4g, d are diagrams of signals at the output of trigger 6, on Topfcix several successive cycles: the measurements are located one under the other, and the beginnings of transients are aligned (for consistency). It is strictly believed that the countdown of the transition process is over. at | the achievement of the pulses g, d of definite duration. The investigator, changing the synchronization delay of the starting impulse relative to the front (rear) edge of the impulse of the investigated | pedal frequency by the value of t And in two: the next measurement cycles, we received} different values of the transition process time (points t, t, tt, on fig.4z). To points) t-t can correspond to the value of the measured transient time c. famous meter. The point corresponds to the measurement result of the proposed meter.

: In a well-known meter, which does not provide for synchronization of the starting pulse with the logic levels of setting the initial position TpHrrepaj and with the pulses under study; frequencies, a random synchronization of the starting pulse can occur along the front or back edge of the pulse with a significant error and significant error thus, the appearance of the reliability of the result can be created. (methodical error).

In the proposed meter, the introduction of synchronization of the starting impulse relative to the leading or trailing edge of the impulse of the frequency under study allows decreasing the probabilistic and eliminating the methodological errors of the measurement, or.

In order to eliminate the method error in the previous meter, each subsequent pulse Start through the control device 11 reverses trigger 6 to the opposite previous state. For example, in Fig. ZD, it can be seen that after the start pulse has been applied, the trigger 6 is in the same state as in the previous measurement cycle. In this case, the control device 11 transfers the trigger 6 to the opposite state (see Fig. Back point t.j |). If, after the starting pulse has been applied, trigger 6 is in the opposite hygred state, then the trigger is not transferred.

The proposed meter improves the accuracy of measuring transient transients 6-8 times.

Claims (1)

Invention Formula Transient time meter for setting the frequency of auth. No. 505127, characterized in that, in order to improve the measurement accuracy of short-term frequency setting transients by averaging successively obtained measurement results, a second averaging device, a recorder and a control unit are inserted, the two outputs of which are connected respectively to the inputs of the zero setting and the trigger unit and its two inputs are connected respectively to the control input "H of the first to the second keys, while the third input of the control unit is connected to the output of the reversible counter ik, and its fourth input is connected to the input of the starting KV; the pulse of the digital clock, the output of the KOToptJX through the second averaging device is connected to the input of the recorder. t.o 0.9 a in .f M .0 Start IG