JPH0990067A - Time measurement method between two analog electrical pulses - Google Patents

Abstract

(57) Abstract: Time measurement between two analog electric pulses having no constant amplitude repeated at an arbitrary frequency is performed with high accuracy. SOLUTION: Each of the two analog electric pulses for measuring the interval is converted into a logic signal by a converter, and the number of output pulses of a separate oscillator is set at the beginning (leading edge) of the two pulses.
And between the logical difference signal and each end (trailing edge) of the two pulses to determine the time between both analog electrical pulses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the time between two analog electric pulses which do not have a constant amplitude and which are repeated at an arbitrary frequency.

[0002]

2. Description of the Related Art For example, when a pulse signal is output in proportion to the rotational speed of a gear that rotates at a high speed to measure the rotational speed from the pulse interval, or when an optical pulse is emitted to a reflector such as a reflecting mirror. Then, when measuring the distance to the reflector from the round-trip time of the light pulse, or measuring the position of the break point from the time until the light pulse is reflected at the break point through the light pulse through the broken optical fiber In some cases, or as in experiments, for example, measuring the internal gain of a detector with a photomultiplier tube, the rise time of the electrical pulse is much slower than the required measurement accuracy and the time between two electrical pulses is Is very long compared to the pulse width of each electrical pulse, it is necessary to accurately measure the time between two pulses.

[0003]

For example, when distance measurement is performed from the time between two pulses, the amplitude of each pulse is not constant due to temperature and atmospheric fluctuations. In order not to affect the fluctuation of the above, the temporal median value of each pulse is obtained, and the time difference between the temporal median values is taken as the time difference between both pulses. The conventional method of finding the median time of each pulse is to differentiate the pulse waveform and use the position of the maximum value or the minimum value where the differential value becomes zero as the time median value of each pulse. The accuracy cannot be obtained, and the measurement accuracy of 30 picoseconds, which is equivalent to the measurement accuracy of less than 5 mm required for distance measurement, cannot be satisfied.

On the other hand, an oscillator and a counter for counting the number of pulses generated from the oscillator are separately provided, and from the generation time point of the first pulse of the two pulses to be measured to the generation time point of the latter pulse. A method is known in which the time between two pulses is measured from the number of pulses counted by a counter. In this method, it is possible to satisfy the above-mentioned measurement accuracy of about 30 picoseconds by increasing the oscillation frequency of the oscillator. However, in this method, the measurement accuracy varies greatly depending on how each pulse generation time point is specified. If the amplitude of the pulse to be measured is constant, the pulse generation time point is specified under the same conditions for each pulse. However, if the pulse amplitude fluctuates as described above, the condition for specifying the pulse generation time is not constant for each pulse, and the method cannot be applied.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to improve the accuracy of time measurement between two analog electric pulses even when the amplitude is not constant.

In the measuring method of the invention, two analog electrical pulses enter one signal line with one comparator, or two separate lines each with one comparator. And convert the analog electric pulse into a logic signal. Especially in the case of a high speed signal, it is desirable to use a comparator whose output side is ECL compatible so that the switching time is extremely fast and the signal can be reprocessed in a shorter time than the pulse width of the pulse to be measured. The comparator provides a switching time of about 1 nanosecond. However, the switching time corresponds to a measurement error of 15 cm when applied to distance measurement, for example, and is never satisfactory. Therefore, in order to avoid being affected by the measurement limit of the comparator and the rise time of the analog electric pulse to be measured, after converting the pulse into a logic signal by the comparator, the second pulse is started from the beginning of the first pulse. From the end of the first pulse to the second
Measure the time to the end of the pulse. A method of counting the number of pulses generated by a separately provided oscillator is used for the time measurement. Then, the time from the center of the first pulse to the center of the second pulse is obtained by dividing the sum of both measured times by 2. According to this method, it is irrelevant to the fluctuation of the amplitude of the pulse to be measured and the measurement limit of the comparator, and to the rising time of the pulse to be measured. Further, by repeating the measurement, it is possible to improve the measurement accuracy up to the point where the residual error becomes a systematic error.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for measuring the time between two analog electric pulses of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic diagram of an electronic circuit arrangement for implementing a method for measuring the time between two analog electrical pulses, which are repeated at arbitrary frequencies but whose amplitudes are not constant (including statistically distributed cases). . FIG. 2 shows a logic pulse diagram.

The incoming analog electrical pulse 1 is within the analog modulation range of an amplifier not shown. The analog electric pulse 1 which is an analog signal is converted into a logic signal 19 by the comparator 2 using the reference voltage 22 as a threshold value. The reference voltage 22 is set so that a sufficient S / N ratio can be secured and erroneous detection can be eliminated with an extremely high probability. The output of the comparator 2 is ECL compatible and has a positive output terminal and an inverting output terminal. The ECL compatibility control signal 3, which is applied before the entry of the first analog electrical pulse, is used to convert the outputs 4, 5 of the fast ECL flip-flop 6 to their respective logic states on the rising edge. Flip flop 6
Q output 5 of is connected to its own data input 7. One output of the comparator 2 and one output of the flip-flop 6 are passed through the ECL-NOR gate 8, and the other output of the comparator 2 and the other output of the flip-flop 6 are ECL-NO.
It is passed through the R gate 9. The outputs of the two NOR gates 8 and 9 are logically ORed by the fixed wiring 10 of the ECL output, and are guided to the clock input 11 of another high speed ECL flip-flop 12. The flip-flop 12 has been set to the ground state in advance by the control pulse. Another flip-flop 13 prevents three or more analog electrical pulses converted into logic signals from working in the flip-flop 12. By the periodic inversion of the flip-flop 6, the positive side pulse or the negative side pulse is passed through the NOR gates 8 and 9, respectively. As a result, the flip-flop 12 produces at its output 14 a gate pulse 14a at which the converted analog electrical pulse is inverted from the leading edge to the leading edge and from the trailing edge to the trailing edge. The gate pulse 14a is sent to the NOR gate 17, and the NOR gate 17 gates the time counting pulse output from the high-frequency precision oscillator 15 into the counter 16. A high frequency precision oscillator 15 between the two leading edges and between the two trailing edges of the two analog electric pulses thus converted.
The number of output pulses of 1 is counted by the counter 16. On the other hand, the second counter 18 separately counts the number of divided pulses. The oscillation frequency of the high-frequency precision oscillator 15 is set to, for example, 30
With an oscillator frequency of 0 megahertz and one period corresponding to 100 divided pulses, a measurement accuracy of about 30 picoseconds can be obtained. By increasing the number of divided pulses corresponding to one cycle, it is possible to set the time much shorter than the rising time of the analog electric pulse, and from the center of the first analog electric pulse to the center of the second analog electric pulse. From the measurement result of 1, the influence of the rise time and the fall time of the analog electric pulse is almost eliminated, and the measurement accuracy can be improved.

By applying the method of the present invention, the time between two analog electrical pulses is measured by indirectly measuring the time between the centers of the two analog electrical pulses, thereby varying the amplitude of each analog electrical pulse. It is hardly affected by the rise time or the limit of the processing speed of the comparator. Further, the measuring method of the present invention can be implemented by an extremely simple circuit technical means. Further, according to the present invention, since the variation in the amplitude of the analog electric pulse to be measured and the limit of the processing speed of the comparator are not affected, the time measurement accuracy is significantly improved.

FIG. 3 shows a second embodiment of a circuit configuration for carrying out the present invention by extracting portions different from those shown in FIG. The two analog electrical pulses enter two separate lines. In that case, one comparator 2A, 2B is connected to each of the two lines, and E of each comparator 2A, 2B is connected.
CL compatibility positive output 19/20 is ECL compatibility OR / N
It is directed to an OR gate 21, whose negative and positive outputs are respectively directed to separate ECL compatible NOR gates 8 and 9. NOR gates 8 and 9 are alternately turned on by flip-flop 6 shown in FIG. Incidentally, the portions other than those shown in FIG. 3 are equivalent to those of the circuit shown in FIG.

[0012]

According to the present invention, the time measurement between two analog electric pulses which do not have a constant amplitude and which is repeated at an arbitrary frequency is performed by the variation in the amplitude of each analog electric pulse, the rise time or the processing of the comparator. Obtained with almost no effect on the speed limit, a significant improvement in time measurement accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an electronic circuit device for implementing the time measuring method of the present invention.

[Figure 2] Logic pulse diagram

FIG. 3 is a partial schematic view of a second electronic circuit device for carrying out the time measuring method of the present invention.

[Explanation of symbols]

 1 analog electric pulse 2 comparator 6 flip-flop 12 flip-flop 15 high frequency precision oscillator 16 counter 17 NOR gate 19 logic signal 22 reference voltage

Claims (3)

[Claims] 1. A method of measuring the time between two electrical measurement signals in the form of short analog electrical pulses, which have non-constant or statistically distributed amplitudes and which can be repeated at any frequency, The measurement of two analog electric pulses each makes a total measurement, and the high speed compensator converts the analog electric pulse into a logic signal having the same width as the analog electric pulse of the voltage value applied to the reference input of the compensator 2. , Directly using the time between the two leading edges of these logic signals and the time between the two trailing edges in equal proportions as start-stop times for counting the switching ends of the oscillator or integrating the voltage and A method for measuring the time between two analog electric pulses, characterized in that it is used as a start / stop time for subsequent digitization of the integrated voltage value and addition of this value. 2. The method according to claim 1, for measuring the time between two measurement signals in the form of short analog electrical pulses which are repeatable at any frequency.
[Emitter-Coupled Logic] A flip-flop 6 which has a compensating output for compatibility, positive and negative outputs respectively being led to ECL compatibility NOR gates 8 and 9 and which is switched by the control signal 3 before the entry of the measurement signal. The NOR gates 8 and 9 are alternately turned on so that the outputs of the two NOR gates 8 and 9 are logic O.
Flip-flop 12 collected in R circuit 10 and divided by two
, Which was previously grounded by the control signal 3 to the clock input 11 of the, the gate signal from the leading edge to the leading edge and from the trailing edge to the trailing edge of the measurement signal converted into the logic signal is Alternately formed at the output of flip-flop 12 and time measuring and evaluating this gate signal at the same rate for subsequent evaluation, and divide by two so that each flip-flop 12 has two or more gates per passage of two measurement signals. A method for measuring the time between two analog electrical pulses, characterized in that the formation of a signal is blocked by another flip-flop 13, which is also grounded by the control signal 3. 3. A method as claimed in claim 1, for measuring the time between two measurement signals in the form of short analog electrical pulses, which can be repeated at any frequency. If each line has a second measurement signal entering the other line, one for each line with an ECL compatible output.
Positive outputs 19 and 20 of each compensator are ECL compatible OR / N
A method for measuring the time between two analog electrical pulses, which is collected in an OR gate 21, the positive and negative outputs of which are reprocessed in the same way as the compensator output of claim 2.