SU495639A1 - The method of measuring time intervals - Google Patents

Description

one

The invention relates to the measurement of small time intervals.

There is a known method of measuring and selecting time intervals based on the conversion of an interval to an analog value (voltage) with a Pomongo shock-excited circuit. According to this method, at the beginning of the measured interval, the current through the circuit is abruptly increased to a certain value, and at the end of the interval it is also abruptly reduced to its original value. As a result of such an action, damped oscillations are established in the circuit, the amplitude of which is determined by the ratio between the frequency of tuning the circuit and the duration of the monitored interval. The magnitude of the interval is then judged by this amplitude.

The known method has the disadvantage that when one of the two pulses forming a time interval disappears, the subsequent measurement of the voltage amplitude on the circuit gives obviously false readings, which leads to an erroneous judgment about the size of the interval and its deviation from its nominal value. In a number of cases, such errors are unacceptable.

The aim of the invention is to eliminate the erroneous readings and the disappearance of one of the pulses, which generate a time interval.

This goal is achieved by choosing the frequency and the initial phase of oscillations of the generator so that the voltage taken from it is zero across zero at the moment corresponding to the end of the time interval and its nominal value, measures the instantaneous value of this voltage and its sign at manifestations of the second pulse, by which the magnitude and sign of the deviation of the time interval from the nominal value is judged.

FIG. 1 shows a block diagram of a device that implements the proposed method; in fig. 2 - process graphics.

The device consists of three main components: the pulse distributor 1, the generator 2 of shock excitation and the meter 3 instantaneous voltage values. Auxiliary node 4 returns the circuit to the initial state before the beginning of each new measurement cycle. The pulses forming the measured interval are fed to the input of the first node, the purpose of which is that the first pulse starts the generator 2 but does not pass to the input of control 5 of the meter 3. The second pulse must be passed by the first node to the input control 5, whereby the measurement 3 at the time of the second pulse produces a measurement of the voltage of the hecherator.

FIG. 2 s; depicts imgulsa, the interval which is to be measured. Pulse I corresponds to the beginning of the interval, and IMpulses II, III, IV-the end of the interval when its values are different: impulse II corresponds to a reduced interval, impulse 1P - to the common pulse, impulse IV - to the increased one. FIG. 26 shows the voltage (/ generator of the shock excitation generator 2. Voltage (coal occurs at the time i of the occurrence of pulse I, and at time 4, corresponding to the nominal interval value, it passes through zero. The occurrence of nm II, III or IV nm) The instantaneous value of the voltage value / 7gen (meter 3). If the monitored interval t is equal to the nominal value (t Tn), then the zero value will be measured; if, then the value will be fixed as a result of the measurement. The value will be fixed. U value (equal U + il Y) is stored node 3 to the next round (or longer). The magnitude U is judged to dismiss the interval of the nominal value, ie. E. On the value of.

Within some limits, / and A / are uniquely linked. For the case depicted in FIG. 26, this relationship is expressed as:

tm

and

2-. „

where E is the voltage amplitude LW

In the general case, depressions (/ a gene may have a different initial phase, cf and frequency). For such a general case, you can write:

 at (j.j

Lg - - sin 2- (I t,) + 9 with A I

It turns out that condition 6reii 0 for. requires a ratio of:

2./t „+,. -.-. k, (2)

where k is any n, a single number (/ e - 0, I, 2, ...). FIG. 26 shows the case 0, f -.

For this case) (the link between LJ and Lt is given by the following dependency obtained from expressions (1) and (2):

and - (- l) Esin2-f -: - (-) Е sin X

nk - v dt

X |

ABOUT -

From this formula you can find an expression for the maximum relative change of 60 (.: With „)„ ax, which preserves the unambiguous relation between t / and Lt

: -, -

 - O / fc

 n max- ("- {

For example, for the case depicted in FIG. 2 b

 - I - :: - ± 1, Ie. L. -: „,,, -; ± t "

 -C / 113KS

Using this method, tuning the generator of shock excitation according to the ratio (2) can be performed using a known value Tn or Tn, specified from a reference device, but unknown in absolute time units. In the first case, this method can be used to measure the absolute value of Dg, and in the second case, only measure the relative deviation A

On fi1-. 2 c shows the case when in the ratio (2) is chosen f 0,. In this case, the frequency of the voltage 6gp is higher than the frequency (J - ,,, in Fig. 26. As can be seen, the region of unambiguity is less here than in

the previous case, namely Atmax - but

but with the same values of At, the value for FIG. 2 in (ULH Di-) is larger than for FIG. 2 a (assuming the amplitudes of the amplitudes are equal (/ gene and f / gene). Therefore, for the case shown in Fig. 20, the accuracy of the instantaneous values of L / and, consequently, the values of Am is higher. Thus By applying a generator with a higher frequency, it is possible to improve the accuracy of the measurement, due to the narrowing of the range of the At. In particular, in Nribor, based on this method, it is possible to provide several ne / switchable generators with a frequency of .m; - (t. . Different cf and k), thanks to what: ipHooj) will become multi-scale.

In section 1, when one of the pulses forming from., The first interval is absent, the remaining one; The impulse will trigger the startuja genera of shock excitation, however, by changing the MniOuCHi-ioro value of U, there will not be a uc ijcvBJieno, l Neither meter 3 output after; i, and the zero voltage will turn out to be another cycle. This rezu.CH - / gat will be the same as if the measurement of At did not take place at all in this center; 1. Consequently, there will be lack of any data for a false judgment about the value of Am.

Claims (1)

Invention Formula A method for measuring time intervals by converting an interval to an analogous value, for example, voltage, from: to the bottom of the shock-excited contact; this is where the shock excitation generator of this circuit is started simultaneously with the HiniciKCM first pulse forming the measured time interval , characterized in that the UTR, in order to eliminate erroneous readings when one of the pulses enters, the frequency and the initial phase of the oscillator oscillations are set so that the voltage removed from it passes through zero at the moment corresponding to the end of the time interval at its nominal value, the instantaneous value of this voltage and its sign are measured at the moment of the appearance of the second pulse, by which the value and sign of the deviation of the time interval from the nominal value are judged.