SU1597859A2 - Meter of time intervals - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure time intervals. The aim of the invention is to improve the noise immunity of the device. The time interval meter contains the generator 1 of the reference frequency, the control trigger 2, the time selectors 3, 6, the scaling circuit 4, the counter 5 pulses, the element NOT 7, the block 8 of the prohibition. The emergence of new connections due to the introduction of element I 9 makes it possible to achieve the objective of the invention by eliminating the component of the error caused by the uncertainty of the time of arrival of the measured signal. 1 il.

Description

ate yu

00

ate yu

Yu

The invention relates to the measurement technique and is an improvement of the invention according to the author. St. N ° 669332.

The purpose of the invention is to improve the noise immunity of the device.

The drawing shows a structural diagram of the meter time intervals.

The time interval meter contains a reference frequency generator 1, a control trigger 2, a first time selector 3, a counting circuit 4, a pulse counter 5, a second time selector 6, a HE element 7, a prohibition block 8, and an AND 9 element whose output is connected to a control the input of the selector 6, the second input of the element And 9 is connected to the output of the element NO 7, and the first input to the output of the trigger 2, the control input of the selector 3 and the input of the block 8, the first output of the block 8 is connected to the second input of the counter 5, and the second output - to the third input of the counter 5, the first input connected to the output of the selector 3, connected by a signal input to the output of the generator 1 and the signal input of the selector 6, the output of which is connected to the counting input of the counting circuit 4, the input bus meter is connected to the input element HE 7, the R input of the counting circuit 4 and the second input trigger 2, the first input of which is connected to the output of the scaling circuit 4.

Control trigger 2 is an RS-type trigger, the R input of which is the first input of trigger 2, the S input is the second input of trigger 2, and the direct output is the output of trigger 2.

The time selectors 3 and 6 are the AND element, the first input of the AND element is the signal input of the selector, the second input of the AND element is the control input of the selector, and the output of the AND element is the output of the selector

The conversion factor N of recalculation scheme 4 is determined by the formula

N Z Uconst f,

where A is a tconst-selected time constant greater than the duration of the maximum inter-pulse interval in the measured burst;

f is the pulse frequency of the generator 1 of the reference frequency.

Pulse counter 5 is a summing counter, the counting input of which is the first input of counter 5, the enable input of the parallel code recording is the second input of the counter 5, and the receive inputs of the parallel code are the third input of the counter 5,

The prohibition block 8 contains a pulse driver that operates on the leading edge of the input signal, an additional code register and a code recording node connected by its outputs to the register inputs, the shaper output pulse duration being less than the reference frequency generator 1, and the code recording node The register contains 0 additional code for the value of the recalculation coefficient N of the scaling circuit 4. The input of the pulse shaper - the input of block 8, the output of the shaper of pulses -, the first output of block 8, and the outputs of Register reg. 5 second output of block 8.

In the initial state of the time interval meter, at the output of the element NOT 7 there is a logic level G, and at the output of the trigger 2 and at the output of the element AND 9 0 the level of logic O, and the generator 1 pulses do not pass through the selector 3 to the counter input of the counter 5 and through the selector 6 to the counting input of the counting circuit 4, the initial state of the counter 5 can be any one, and the initial state of the counting circuit 4 is zero.

When a signal meter is received on the input bus, it is a burst of pulses; the first signal pulse

0 at the S-input sets at the output of trigger 2 the level of logic 1, at the output of the element NOT 7 - the level of logic O and confirms the R input of the zero state of the scaling circuit 4. The transition of the logical 5 O into logical 1 from the output of trigger 2 is fed to the input block 8 prohibition, where the formation of a pulse, the leading edge of which carries information about the change in the value of the input signal. This pulse from the first output of the prohibition block 8 by the leading edge writes into the counter 5 of the register of the prohibition block 8 an additional code of value N. At the same time, the logic level 1 from the output of the trigger 2 gives a permission for the generator 1 to pass through the counting input of the counter 5.

At the end of the first impulse of the input signal at the output of the element And 9, the logic level 1 is set, since the first input of the element And 9 from the output of the trigger 2 contains the logic level 1, and the second input of the element 9 from the output of the element 7 sets the logic level one.

The level of logic G from the output of the element And 9 gives permission to pass through the selector 6 pulses of the generator 1 to the counting INPUT of the counting circuit 4.

The second input signal pulse via the S-input confirms the logic level 1 at the output of trigger 2, sets the logic level O at the output of the element 7, and sets the recalculation circuit 4 at the R input to the zero state. At the same time, the logic level O from the output of the element NE 7 the second input sets at the output of the element And 9 the level of logic O, prohibiting the passage through the selector 6 of the pulses of the generator 1 to the counting input of the scaling circuit 4. At the end of the second pulse of the input signal, a process similar to cession after the first input pulse.

Such a cycle of operation of the meter ends with the moment of the end of the last pulse of the input signal when logic level 1 is set at the output of element 9, which gives permission for pulse 1 of generator 1 to pass through the counting input of the counting circuit 4. After the counting input of the counting circuit 4 generator 1 pulses, the number of which is equal to the value of the recalculation coefficient N, recalculation circuit 4 generates an overflow pulse that sets the logical level O on the R output of the trigger 2 output. This level of logic O prohibits the passage of the generator 3 pulses through the selector 3 to the counting input of counter 5 and simultaneously sets the output of element I 9 to the logic level O, which prohibits the passage of generator 3 pulses through the selector 6 to the counting input of counting 4, leaving the recalculation circuit 4 in the zero state.

Thus, the counting input of the counter 4 receives the number of pulses of the generator 1, proportional to the duration of the input signal and the value of the selected time constant. Since the additional code 4 of the value N is recorded in the counter 5 before the measurement, after the completion of the measurement the code corresponding to the duration of the input signal is written in the counter 5.

The algorithm of the meter operation when performing measurements of a pulse signal waveform is similar (a pulse wave signal is a burst of pulses, the number of pulses in which is one).

The use of simple means (an additional element and new connections) in the proposed meter makes it possible to eliminate the loss of information when measuring the duration of a pulse-shaped signal and to improve noise immunity. In addition, when measuring the duration of a burst of pulses, the component error is excluded due to the uncertainty of the time of arrival of the measured signal and determined by the formula

 P

.., oo%,

where G1 - the duration of the first pulse signal:

- G1 is the duration of the first interpulse interval in the signal:

GA-duration of the measured signal.

As a result, for example, when measuring the duration of radiation of a laser in free-running mode with parameters of GA 200 MKS, G1 5 MKS MKS, the measurement error is reduced by the value g 5%.

Claims (1)

Invention Formula Meter time intervals for auth. St. Ns 669332, distinguished by the fact that, in order to improve the noise immunity of the device, an element I is entered into it, the first input of which is connected to the output of the element NO, the second input to the output of the trigger, and the output to the control input of the second time selector.