JPH0510607B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a multi-item measuring method that can extremely easily obtain the values of a plurality of drifting measured items at the same time without using any special equipment. Regarding.

[Technical background of the invention and its problems]

The conventional methods used to measure the amount of drift over multiple items are to make all the necessary measurements in the shortest possible time, or to prepare as many measuring instruments as there are items to be measured. I was trying to perform simultaneous measurements.

However, in the former method, a time difference remains between the measurement times of each measured item, and it cannot be adopted when there is a measured item that requires a long time to measure. Furthermore, in the latter method, it is necessary to prepare as many measuring instruments as the number of items to be measured, so it is not practical, especially when there are many items to be measured or expensive measuring instruments must be used. Another problem is that even if multiple measuring instruments are connected and controlled via a bus such as the IEEE488 bus for simultaneous measurement, a special control device must be prepared in order to send triggers to all of them at the same time. There is. Furthermore, there are some items to be measured that cannot be measured at the same time.

The above-mentioned drawbacks of the conventional techniques become a major problem when high-precision measurement is required.

[Purpose of the invention]

The present invention solves the above-mentioned drawbacks of the prior art and provides a method for measuring multiple items that can obtain values at the same time of multiple drifting items with high precision and without the need for special equipment. The purpose is to

[Summary of the invention]

In order to achieve the above object, in the present invention,
Among a plurality of items to be measured, the values are measured in order of decreasing drift, and then the values are measured in reverse order. By averaging the measured values obtained in this way for each measured item or performing other arithmetic processing as necessary, the values of each of the multiple measured items at the intermediate time of various measurements, that is, at the same time, can be calculated. It can be calculated.

The reason for performing measurements in this order is as follows.

In order to reduce the error when calculating the value of the amount of drift at the reference time (the above-mentioned "same time") from the times in its vicinity, it is generally necessary to satisfy the following conditions: 1) The actual measurement 2) Minimize the deviation of the measured value from the reference time value as much as possible (the smaller the deviation of the measured value, the smaller the residual error that cannot be corrected by the correction calculation).

Furthermore, considering the purpose of the present invention, which is "highly accurate measurement of multiple items," it is desirable from the viewpoint of overall balance that almost uniform accuracy be obtained for all items.

Furthermore, the time relationship between the time when a certain item is measured and the reference time must be as similar as possible to the relationship between the time when another item is measured and the reference time. For example, if item A is measured at the reference time -
100mS and -50mS, and for item B, the reference time is +50mS and +100mS because these measurements are performed in completely different time relationships with respect to the reference time, so there is no difference in the measured values of both items. This is undesirable because the appearance of drift and, ultimately, the errors in the values of each item may vary. Also,
In order to avoid such non-uniformity, if all measurements are taken before (or vice versa after) the reference time, compared to the method of measuring some before and the rest after, the above The degree of departure from condition 1 increases.

Therefore, under the constraints assumed by the present invention,
For each item, perform measurements across the reference time (in other words, the first measurement is made before the reference time,
It is desirable that the second measurement be performed after the reference time.

When performing measurements across such reference times, in order to measure all items with almost uniform accuracy, it is necessary to
The measurement conditions may be made more advantageous for items with larger errors. Specifically, considering condition 2) above, it is necessary to make the interval between two measurements shorter for items with larger drifts.
In other words, if you first measure each item in order of the smallest drift, measure the item with the largest drift, and then measure each item in the reverse order, the above conditions will be satisfied and the reference time ( central time)
The value of each item in can be calculated with almost uniform high accuracy for all items.

Of course, for items to be measured whose drift is sufficiently small, the above-mentioned round-trip measurement may be omitted and only one measurement may be performed.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows an example of a configuration for carrying out the multiple-item measuring method of the present invention.

FIG. 1 is a block diagram for measuring high frequency power using a thermistor power sensor. Here, 11 is a high frequency power supply, 13 is a thermistor power sensor, 15 is a high precision voltmeter, 17 is a bus, 19
is a control device that controls the voltmeter 15 via the bus 17.

Figure 2 shows the thermistor power sensor 13 in Figure 1.
FIG. Here, the thermistor 27 to which the high-frequency power P is applied and the thermistor 29 for temperature compensation are each one side.
It consists of two bridges. The differential amplifiers 21 and 23 automatically bring these two bridges into equilibrium. The output voltages of the differential amplifiers 21 and 23 at this time are assumed to be W and V, respectively. Further, G is a ground potential. Furthermore, the voltage U shown in FIG.
the difference between the two voltages, i.e., V-W. Here, if the voltage U when the power P to be measured is not applied and when it is applied are respectively expressed as U ₀ and U ₁ , then the power P
As is well known, P={2V(U ₁ −U ₀ )+U ² ₀ −U ² ₁ }/(4RC)
...(1) is obtained as follows. However, in equation (1), C is a constant specific to the thermistor power sensor 13 used here. Also, R is R for each of the two bridges in Figure 2.
is the value of the resistance marked as .

However, as the ambient temperature changes, the voltage
Since U ₀ , U ₁ , and V drift, if there is a difference in the measurement time of the voltages U ₀ , U ₁ , and V used on the right side of equation (1),
If highly accurate power measurement is required, an accurate value of power P cannot necessarily be obtained. Furthermore, it is extremely difficult or impossible to obtain these measured values at the same time. Therefore, among these three items to be measured,
The measurements are carried out in the following order, noting that the drift of voltage V is much larger than the others.
That is, first the voltage U ₀ , then the voltage U ₁ , and then the voltage V
Then, in the reverse order, voltage V, voltage U ₁ ,
Measure the voltage U ₀ . The order of this measurement is shown in FIG. Note that, as can be seen from FIG. 3, measurements were performed three times at each measurement point. This is to obtain one measurement value by averaging three measurements in order to avoid the influence of noise and the like. Naturally, this number of times is not limited to three times.

The measured values U ₀₁ , U ₁₁ , V ₁ , V ₂ , obtained at times T ₁ to T ₆ with the time interval T _H as described above, respectively.
From U ₁₂ , U ₀₂ , voltage U ₀ at intermediate time _TM ,
The values of U ₁ and V are obtained by estimating the values as follows.

U ₀ = (U ₀₁ + U ₀₂ )/2, U = (U ₁₁ + U ₁₂ )/2 V = (V ₁ + V ₂ )/2 By substituting the values obtained in this way into equation (1), An accurate value of power P can be obtained.

Note that the order of measurement may be determined depending on other circumstances between items to be measured whose drifts are approximately the same.
For example, in the above example, the drifts of voltages U ₀ and U ₁ are approximately the same. However, of course these two voltages do not exist at the same time (the third
(The dashed line in the graph in the figure indicates an area where that voltage does not actually exist). Therefore, since it is preferable to use a value measured at the time when the power P is actually applied as the voltage V, the measurement order as described above is adopted.

In addition, in the above embodiment, in order to estimate the value of each measurement item at an intermediate time, linear approximation was performed based on two values at symmetric times with respect to the intermediate time, but of course other approximation methods can be used. You may also use

Furthermore, the measurement intervals can be freely set as necessary, and do not necessarily have to be set at equal intervals.

〔Effect of the invention〕

As described above, according to the present invention, values of a plurality of measured items at the same time can be obtained easily and with high accuracy. Therefore, the present invention is very effective when obtaining the value of another quantity indirectly from the values of a plurality of measured items. For example, in the above example, the repeatability of measurements using the conventional method is 0.1.
By adopting the method of the present invention, it was improved by two orders of magnitude to 16 PPM, which was about 0.3%.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a configuration for carrying out the multi-item measuring method of the present invention, FIG. 2 is a circuit diagram of the part that generates the signal under test in FIG. 1, and FIG. FIG. 3 is a diagram illustrating an example of the multiple-item measuring method of the present invention, which is performed using the configuration and circuit shown in FIG. 2; 11... High frequency power supply, 13... Thermistor power sensor, 15... Voltmeter, 17... Bus, 19...
...Control device, 21, 23...Differential amplifier, 27,
29...Thermistor, P...Power.

Claims (1)

[Claims] 1. A multi-item measuring method for obtaining the values of a plurality of drifting measured items at the same time, comprising: measuring the values of the plurality of measuring items in descending order of drift, and then measuring in reverse order; A method for measuring multiple items, characterized in that the values of the plurality of measured items at intermediate times are calculated based on the measured values obtained.