SU913327A1 - Device for measuring time interval between symmetrical pulses - Google Patents

Description

The invention relates to a pulse technique and can be used in devices of television and pulse technique to determine the coordinates and time intervals.

A device for measuring time intervals is known, comprising two counters, four triggers, a coincidence circuit, five AND elements, an OR element, two delay lines, a digital meter and a digital display circuit {1).

However, when measuring the time interval between two pulses, the amplitudes and durations of which can vary, such a device has low accuracy and contains a significant number of elements.

The closest to the technical essence of this invention is a device for measuring the time interval between symmetric pulses, containing a threshold amplifier, whose input is the input of the device whose output is connected to the input of the first trigger, with the inputs of the first elements OR and AND, the output of the first trigger is connected. to the second input of the first element And to the input of the vure element And, the output

2

The first element AND is connected to the second input of the first element OR, the output of which is connected to the input 5 of the third element AND, and through the element NOT to the second input of the second element AND whose output is connected to the input of the fourth element AND, the second input of which is connected to the output 10 of the filling pulse generator and the output is connected to the input of the second OR element, the output of which is connected to the counter input, the output of the filling pulse generator through the second trigger is connected to the second • 5 input of the third element And, the output of which is connected to the second the input of the second element OR [2].

The disadvantage of such a device is low measurement accuracy even with large signal-to-noise ratios _? due to the possibility of false positives of the counter, as well as the fact that the state of the second trigger after the end of the measurement does not 25 carry information about the duration of the measured interval.

The purpose of the invention is to increase the point

measurements.

This goal is achieved by the fact that

30 device containing a threshold

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the amplifier, whose input is connected to the input bus, and the output to the input of the first trigger and the first inputs of the first OR and AND elements, the second input of the latter is connected to the output of the first trigger and the first input of the second. AND gate, the second input of which soe- ³ of the connections with the output of the first OR gate through the NOT element, an output of second AND gate connected to the first input of the third AND gate, the second input Ko ... torogo connected to the output pulse duty generator, and an output connected to the first input of the second OR element, the output of which is connected to the counter input, the second trigger and the fourth AND element, one of the 5 inputs of which is connected to the output of the first OR element, the second input of which is connected to the output of the first AND element, Exit pulse generator 20 filling cos coupled to a second input of AND gate whose output; through the second connected in series, the trigger and the pulse shaper is connected to the second input 25 of the second element OR.

The drawing shows a block diagram of the device.

The device contains a threshold amplifier 1, triggers 2 and 3, elements 4-7 AND, generator 8 pulses, padding, elements 9 and 10 OR, driver 11 pulses, element 12 NOT and counter 13. Output threshold amplifier 1 is connected with the entrance of a trigger-35 ger 2, from the entrance; ®! elements 4 AND and 9 OR. The output of trigger 2 is connected to the second input of element 4 I and to the input of element 5 I. The output of element 4 I is connected to the second input of the element. ^ That 9 OR, the output of which is connected to the input of element 6 AND and through element 12 is NOT to the second input element 5 I. The generator output 8 filling pulses are connected to the second input of element 6 I to the input of element 7 I, 45 whose second input is connected to the output of element 5 I. The output of element b I through trigger 3 and the driver®

11 pulses are connected to the input of element 10 OR, the second input of which is connected to the output of element 7 AND,

and the output is connected to the input of the counter 13, the outputs of which together with the output of the trigger 3 are the outputs of the device. 55

The device works as follows. ·

The impulse ’'Start', which arrives at the input of the threshold amplifier 1, is normalized in it in amplitude and causes trigger 2 to be switched before this. A high voltage appears at the output of trigger 2 (state '1' ').

As a result, the output of element 9 OR also appears high

voltage and, therefore, the element b And opens, allowing the passage on the trigger 3 counting pulses from the generator 8 filling pulses. At the output of the trigger 3 in this case there are pulses with a frequency equal to half the frequency of the counting pulses. These pulses through the pulse shaper 11, which forms short pulses according to a positive voltage drop, and element 10 OR arrive at the input of the counter 13. At the output of element 12, NOT at this time there is a low voltage (logical “0”) that covers element 5 AND , and it, in turn, closes element 7 AND, thereby preventing the passage of counting pulses from generator 8 through element 10 OR to the input of counter 13. After the “Start” pulse ends at the output of threshold amplifier 1, element 4 AND closes, output element 9 or arr A low voltage closes the 6 I element. Therefore, the counting pulses to the trigger 3 are no longer received and a code corresponding to half the pulse width “Start *” at the output of the threshold amplifier 1 will be recorded in the counter.

Since after the end of the “Start” pulse, the trigger 2 is in a state with high output voltage and the output of element 12 is NOT high voltage, the output of element 5 also will be the voltage opening element 7 I. At the same time, the counting pulses from generator 8 pass through the element 10 OR to the counter 13. If at this time the trigger 3 is in a state with high output voltage, then after the formation of 11 pulses at this time there will be a low voltage that does not affect the operation of the element 10 OR and the counter 13. When the pulse arrives Stop 'at the entrance The force 1 trigger 2 is tilted to its original state with a low output voltage. Element b AND opens with a signal from element 9 OR (as during the “Start” pulse ¹ ), and with the same signal passing through elements 12 NOT and 5 AND, element 7 And closes. Therefore, now the counter, as in the presence of the “Start” signal, will pass pulses with a frequency equal to half the frequency of the counting pulses.

At the end of the signal "Stop" at the output of the threshold amplifier 1 at the output of element 9 OR - low voltage, the closing element b And, and since the output of the trigger 2 low voltage, then at the output of the element 5 And low voltage, closing element 7 I. In this case, the pulses to the input of the counter 13 do not pass and the counting is stopped until the next signal appears.

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'' Start ' ¹ . In the interval between the “Stop” and “Start” pulses, it is necessary to reset the counter 13 and the trigger 3, and to eliminate the failures - the trigger 2.

Thus, as a result, the output of the counter 13 has a time code corresponding to the sum of half the durations of the '' Start '' and '' Stop '' pulses and the duration of the gap between them, which with the symmetric 'Start' 'and' 'Stop' 'pulses corresponds to the duration of the interval between their midpoints. The lowest code bit is determined by the state of trigger 3.

The increase in accuracy compared with the known device is due to the absence of possible false alarms of the counter 13 when the element 6 is opened. And the possibility of using information from the trigger output 3. In case the “Start” and “Stop” pulses are synchronized with the counter pulses, As is the case when processing a video signal with multi-element photodetectors, the accuracy of time interval measurement is equal to half the interval duration of the counting pulses for any duration of the '' Start '' and '' Stop '' pulses.

Claims (1)

Claim Device for measuring the time interval between symmetrical pulse containing a threshold amplifier, the input is connected to: the input bus, and the output with the input of the first trigger and the first inputs of the first elements OR and AND, the second input of the last connected to the output of the first trigger and the first input of the second element, And the second input which is connected to the output of the first element OR through the element NOT ,, the output of the second element AND is connected to the first 'input of the third element AND, the second input of which is connected to the output of the generator of filling pulses, and the output connected to the first input of the second element OR, output d soe15 union of which to the counter input of the second trigger and the fourth element AND, one of the inputs of which is connected to the output of the first element OR, the second input of which is connected to the output 20 of the first element AND, distinguished by the fact that, in order to improve the measurement accuracy, a pulse shaper is inserted into it, and the output the pulse generator 25 is connected to the second input of the fourth element AND, the output of which is connected through the serially connected second trigger and the driver of the pulses to the second input of the second element OR. ¹³⁰