SU1196802A1 - Method and apparatus for digital measuring of time intervals - Google Patents

Description

The invention relates to the field of measurement technology, in particular

to the measurement of time intervals, it can be used in automation, computing, transformation. The aim of the invention is to improve the measurement accuracy and simplify the method of its implementation. The method involves the formation of

the reference pulse sequence, the pulse filling of this sequence of the measured time interval, the counting of these pulses laid down on the measured interval, and the analysis of the states of this sequence at the beginning and end of the measured interval. This goal is achieved by the fact that in the analysis of isolated events, consisting in the fact that the state of the pulse sequence corresponds to a logical one. From the result of counting the pulses of the reference sequence, subtract the value equal to half of the number of selected events. A device for measuring time intervals', which implements the method, contains a pulse frequency generator ^, a frequency, a counter, a trigger, and four logic elements. ^In:: that it additionally introduced trigger counting. The operation of the device is explained in the description of the invention according to the block diagram and timing diagrams. 2 sec. f-ly, 2 ill.

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The invention relates to measuring equipment, in particular to the measurement of time intervals, and can be used in automation, computing, instrument making. five

The purpose of the invention is to improve the measurement accuracy and simplify the method.

FIG. 1 presents time diagrams illustrating the essence of the method; n ^ fig, 2 '- functional Yu scheme of the device for measuring time intervals.

The measured interval T _{x is} filled with the pulse sequence of the reference frequency of the type square type with a period X (Fig. 1a).

In the general case for the measured interval T _{x is} true

T _х = кТ + ДЦ + дс _г , 20

where k * 1, 2, 3, ...;

DC, - uncertainty in

the location, respectively, of the start and stop pulses 25 relative to the reference frequency.

Depending on the values of ds., Ds _{g, the} moments of the beginning and end of the measured time interval T _x may fall into the state "1" or? 0 "of the reference pulse sequence. All possible cases are shown in Fig. 1b, g, e of.

Because. for plot b (Fig. 1), the beginning and end of Τ _χ fall on "0" $ 5

the pulse sequence, we denote this case as “00”. For plot g (Fig. 1), we have "01", i.e. the beginning of T _x falls on "0", and the ending on "1" of the pulse sequence. Accordingly, for the plot: FIG, 1 e "10", and for the plot, c "11".

Plots b, d, d, e, and h (Fig. 1) dotted lines show the areas in which the start and end times T _x can be located for the corresponding case.

For the plot of b "00", the beginning of Τ _χ is located within the interval of ΐ-to them? - 50 pulse sequence, the end of T _x - within the interval of mn.

From the plot and b (Fig. 1) it can be seen that for the case "00" is true

k1 + 0.57 <T _x ^ k7 + 1.57. 55

The true value of the result of digital measurement K _{C (L} is within

к + 0,5 с Н „ _st с к + 1,5.

Plots v, d, g, and u (Fig. 1) show the signals obtained as a result of the logical multiplication of the pulse sequence and the potential signal equal in duration to the interval T _x . We accept that the result of measuring the time interval is equal to the number of positive fronts on these plots ..

Then for the case "00" from the plot to the result of the digital measurement Τ _Χ Ν _Ο0 =

“К + 1 (as in the considered example to ^β 2, and the number of counted fronts is 3 '). Error of measurement result Δ = N - L _isl . Taking into account the range of probable values Ν „ _{£ Τ} . · The measurement error for the case" 00 "is distributed in the region

% „· '^ Ied nlks * D * oo' * Ν · ο _Ο * Ν„ _ιΤΗ „ _Η

Substituting the boundary values Ν „ _£ ϊ, we get

0.5. <,.

For the case of "01", the beginning of T _x lies in the interval ί-k, the ending - in the interval of pr

k'7 <T _x * k7 + 2ι, therefore

k + 1 <Ν _{Μ (γ} <gk + 2.

From the plot d, the measurement result is Ν ₀₁ - k + 2, therefore,

0 <Δ _Ο1 with 1.

For the case of "10" to 7 t _x ^ 7k + and; to N ist <k + 1.

From the plot and measurement result Ν _<0 =

“K + 1, therefore, 0 g. 1.

For the case of "11" Κ + 0.57 T _x sk. + 1.57;

k + 0.5- = N _{I £ T} c to + 1.5.

From the plot and measurement result

* = k + 2, therefore

0.5 s D ,, / <1.5.

The proposed measurement method includes the correction of the measurement result N by decreasing it by half the number of events consisting in the coincidence of the beginning or end of Tu with the “1” state of the pulse sequence.

Corrected measurement result Ν _κ = N - 0.5? _c , where £ _£ is the number of events. It is easy to show that it is equal to the number "1" in the accepted designation of the cases given in the diagrams,

"00" - £ _c -0, "01", "10" - = 1; “11” - £ _with “2.

Thus, the adjusted

measurement results are:

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Ν _Μ ““ No. _{b (>} , “= k + 1 (no correction is made);

^I 4ι · "0.5 - to + .2 - 0.5k 1 .5 * ·

"Hz · ⁼ Ν> ο '- 0.5 - to + 1 - 0.5 to + 0.5;

Ν _{κ% 4} , = Ν _ν - 1 -к + 2-1- к + 1.

The accuracy of the corrected measurement result DK is determined by the expression

Νκ " _{Μ £ ΤΜΑΚΙ} D _to <Ν * and for the cases considered will be

(к + 1) - (к + 1,5) ЛК „ ₀₀ '<Х (к +' 1) - (к + 0,5);

-0.5 <lk » _O0 « 0.5;

(to + 1.5) - (to + 2) * DK. ₀ , "

₅ (k + 0.5) - (k + 1);

-0.5 & k. _o , 0.5;

(to + 0.5) - (to + 1)

с (к + 0,5) - к;

-0.5 <dk ", ₀ "<0.5;

(0 (к + 1) - (к + 1,5) гдЦ, <

. 4c (k + 1) - (k + 0.5);

-0.5 s. ks ^ h g. 0.5.

The results of the calculations are given

in the table.

Happening location Limit of interval ^T ' Without correction With correction Result measuring Limit errors Magnitude corrections Adjusted result Limit to yugresh- "00" g (k + 0.5) ΐ (to + 1.5) k + 1 from -0.5 to 0.5 0 k + 1. . from -0.5 Up to 9.5 "01" g (k + 1) e (k + 2) to + 2 0-1 -0.5 to + 1.5 from -0.5 TO 0.5 "ten" 1 to g (k +) k + 1 0-1 -0.5 k + 0.5 from -0.5 up to 0.5 "eleven" X (k + 0.5) ^ (to + 1.5) to + 2 0.51.5. -one k + 1 from -0.5 up to 0.5

Thus, the method provides simultaneous correction of both, | and DS _g , while reducing the resulting error to + 0.5+.

A device for implementing a method for measuring time intervals contains a generator of 1 pulses eta- loon sequence, a reversible counter 2, elements OF and 4, the element OR 5, short-circuit trigger 6, the counting trigger 7, the element 8 delay. The first inputs of the elements And 3 and 4 are connected to the output of the generator 1. The second input of the element And 3 is connected to the output of the trigger 6, the installation inputs of which are connected to the tires "Start" and

’Stop.

The output of the element TH 3 is connected to the input of the addition of the counter 2. To the second input of the element AND 4 through the element OR

o connected tires "Start" and "Stop". The output of element 4 is connected to the C input of the trigger 7, the output of which through the delay element 8 is connected to the input of the subtraction of counter 2. The output of the trigger 7, in addition, is the output of a fraction of the fractional part of counter 2.

The device works as follows.

On the signal "Reset" counter 2 and

⁵ θ triggers 6 and 7 are set to the zero state. With the arrival of the "Start" pulse, the trigger 6 is set to "1", opening the element 3 for the passage of the pulses of the generator 1 to the input

55 addition of counter 2. With the arrival of the "Stop" pulse, trigger 6 returns

in the initial state, closing the element 3.

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Pulses "Start" and "Stop" through the element OR 5 arrive at one of the inputs of element 4. If at the moment of impulse "Start" or "Stop" at the output of the generator 1 "1", then at the output of element ₅ a pulse is formed.

In the case of "00" during the measured interval at the output of the element 4, not a single pulse is formed, the trigger 7 remains in the initial state. The result of the measurement is the result of counting at the input of the addition of counter 2, i.e. no correction is made.

In the case of "01" or "10" trigger 7 15

triggered once, while the difference from its output affects the input of the subtraction of counter 2, it will be subtracted from the content "1". But; as at the end of the measured interval in the discharge with a weight of 0.5 units, i.e. in the trigger 7, will be one, then the result of the account on the addition input is adjusted by 0.5 units.

In the case of "11", trigger 7 triggers twice and returns to the initial state. “1” is subtracted from the contents of counter 2, as in the previous case, but since the trigger 7 at the end of the measured interval 0 is in the state “0”, the result of counting by the addition of the counter 2 is corrected by 1 unit.

Delay element 8 required for separation at the inputs of the counter 2 po- ₃₅ positively drops at time "Start" for the cases of "10" and "11" if the counter 2 operates in positive changes. If counter 2 operates according to negative ratios of dam, then delay element 8 carries these differences at the moment of the “Stop” impulse for cases “01” and “11”.

In the second case, the input element 8 must be connected to the inverse output of the trigger 7.

Thus, the device provides simultaneous correction of errors & C and, while reducing the resulting error to ₅₀ ± 0.5 G.

Claims (1)

Claim 1. The method of digital measurement of time intervals, including the formation of a reference pulse sequence, the filling of the pulse of this sequence of the measured time interval, counting the pulses of the reference pulse sequence, stacked on the measured interval, and analysis of the states of the reference pulse sequence at the time of the beginning. and the end of the measured interval, characterized in that, in order to improve the measurement accuracy and simplify the method, the analysis distinguishes events that the State of the pulse sequence corresponds to the logical "1" and subtract the value of the reference pulse sequence from the result of pulse counting half the number of selected events. I 2. A device for digital measurement of time intervals, containing a pulse generator of a reference frequency, a counter, two elements AND, the first inputs of which are connected to the output of the pulses of a reference frequency of the generator, a trigger, 8 and E. The inputs of which are connected respectively to the "Start" and "Stop" buses, and the direct output is connected to the second input of the first element AND, the OR element and the delay element, characterized in that, in order to increase the measurement accuracy, a counting trigger has been entered into it, tires " Start "and" Stop "through the OR element connected to the second input of the second element AND, the output of which is connected to the C input of the counting trigger, the output of which through the delay element is connected to the input of the counter subtraction and is the output of the digit fraction of the counter result, to the addition input of the counter connected to the output of the first element And and the K-inputs of the counter and the counting trigger are combined and connected to the Reset bus. 1196802 ΚΪ Γ ~ 1 g 1 g ι 1 01 - I__ □ ί ................ G ^- ΓΊ P e_ί! " ! Γ "Ί G_G “TS_P_ Ft.1 Branch PPP "Patent", Fu? Uzhgorod, Project St., 4