JPH0754529B2 - Repeated data collection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention sequentially samples data that is repeatedly input by an AD converter, such as measurement of backscattered light that returns when light is incident on an optical fiber. Then, the present invention relates to a repetitive data acquisition device for converting a digital value into a digital value and adding the digital data at the corresponding sampling time.

"Prior Art" The measurement of the backscattered light is used, for example, for detecting a fault point of an optical fiber, and when an optical pulse is incident on the optical fiber, it returns to the light incident side in the scattered light generated in each part of the optical fiber. The level of incoming scattered light (backscattered light) is continuously measured, and the time course of the level of the backscattered light is observed to detect a failure point and obtain an attenuation rate. The backscattered light returning from such an optical fiber has a very small level of about -50 dB with respect to the level of the incident light.
Therefore, to measure this backscattered light, the incident light is repeatedly incident on the optical fiber, and each backscattered light that returns repeatedly is sampled at a cycle corresponding to the resolution, and the data at the corresponding sampling points are added and averaged. Then, the S / N is being improved.

For example, as shown in FIG. 5, the level of backscattered light is a curve.
As shown in 11, it is a signal that decays with time.This signal is sampled at the sampling points indicated by the x points, that is, sampling is performed with the sampling clock 12, and each sampling data is converted into a digital value by the AD converter. ing.

For example, when measuring backscatter data for an optical fiber of 100 km, assuming that the number of each data is 500, the interval per point is 200 m. Currently available
The conversion period of the AD converter is about 0.1 microsecond. It has the ability to convert the backscattered light every 10 m. Therefore, there are as many as 20 pieces of data that can be taken within 200 m, but in the past, one piece of data was used for every 200 m without using these data. For example, 2 ¹⁶ measurements were performed and the corresponding data was used. Was averaged to improve S / N. Therefore, the measurement time is very long, and when viewed from the AD converter, the maximum conversion speed is not effectively used.

An object of the present invention is to provide a repetitive data acquisition device that can effectively use the maximum conversion speed of an AD converter and can perform a large number of averaging in a short time.

"Means for Solving Problems" The present invention samples one back-reflected light at a period of 1 / n of a period corresponding to a conventional desired resolution and adds consecutive n samples. To obtain sample data corresponding to the resolution, obtain similar sample data for a large number of backscattered light, and add the corresponding sample data to obtain the desired data. The same S / N at 1 / n times the number of incidents)
Can be obtained. That is, the repeatedly input data is sequentially sampled by the AD converter and converted into digital values, and the respective digital values are sequentially held in the plurality of first latches. The n (n is an integer of 2 or more) first
An adder is provided for each latch to add the contents of the n first latches. The addition results of the p (p is an integer of 2 or more) adders are latched into p second latches, respectively. The contents of the second latch are stored in the memory. Each time the input data is repeated, the holding in the first latch, the addition by the adder, the holding of the addition result in the second latch, and the cumulative addition of the contents of the second latch to the corresponding sampling point of the memory Is controlled by the control unit.

As described above, in the present invention, for example, only n pieces of sampling data are conventionally used as valid data, but in the present invention, the n pieces of data are added and are effectively used as one representative value. It That is, in the prior art, the data of only the same points of the input data are always added and averaged, but in the present invention, the data between the sampling points of the input data are added and used as the representative data between them, and only AD Since a large amount of data can be obtained by effectively utilizing the ability of the converter and a large amount of data can be added and averaged, data can be collected in a short time.

[Embodiment] FIG. 1 shows an embodiment of a repetitive data collecting apparatus according to the present invention. Repetitive data is input from the input terminal 21, sampled at a constant period by the AD converter 22, and converted into a digital value.

In the present invention, the conversion capability of the AD converter 22, that is, sampling at the maximum speed and conversion into a digital value is performed, and the converted digital value is the first latch L _{11 to} L _44.
Are sequentially latched. In the order of the first latch, four contents in this example are added by the adders 23 _{1 to} 23 ₄ . That is, the contents of the first latches L _{11 to} L ₁₄ are added by the adder 23 ₁ , and the contents of the first latches L _{21 to} L ₂₄ are added by the adder 23 ₂ . The addition results added by the adders 23 _{1 to} 23 ₄ are latched in the second latches L _{1 to} L ₄ . The added data in the second latches L _{1 to} L ₄ are stored in the memory areas 24 _{1 to} 24 ₄ .

Every time data is repeatedly input to the input terminal 21 in the control unit 25, the operation of the AD converter 22, the sequential latch to the first latch, each addition operation in the adder, and the latch of the addition result to the second latch are performed. Further, the data latched in the second latch is input to the corresponding region of the memory, that is, the storage region of the same sampling point data, and the data is cumulatively added.

FIG. 2 is a diagram for explaining the operation of the present invention, in which the input analog signal 11 (FIG. 2A) is input to the input terminal 21, and the conventional sampling is performed as shown in FIG. 2B, for example. As shown in, the data was acquired by sampling with 4 times Tad. However, in the present invention, sampling is performed at intervals of the conversion maximum capacity cycle Tad of the AD converter as shown in FIG. 2C, and each sampled data is sequentially converted into the first latches L ₁₁ , L ₁₂ , L ₁₃ ... Each is remembered. Thus in latched to the first latch sequentially the data of the AD converter 22, sequentially latch from the first latch L ₁₁ again when the latch at the end of the first latch L _44.

From the time t ₁ when the first latch L ₁₄ was first loaded with data, the last first latch L ₄₄ was loaded with data, and the first latch L was again loaded.
Between time T _u between time t ₂ immediately before capturing the data to the ₁₁ of the first group first latch, that is added to data of L ₁₁ to L ₁₄ in the adder 23, the addition result Second latch L ₁
Then, the data of the latched second latch L ₁ is cumulatively added to the corresponding data of the area 24 ₁ in the memory 24. The respective data of the first latches L _{21 to} L ₂₄ are similarly added by the adder 23 ₂ immediately after the data is taken into them, and the addition result is written in the second latch L _2, and the second
Transferring data obtained by adding to the latches in the region 24 ₂ of the memory.

As shown in FIG. 1, when one first latch is used a plurality of times for one input data, cumulative addition is made for data at corresponding points of repeatedly input data. The storage in the area 24 ₁ for the data added first in the first group and the addition value of the data added next, that is, the data taken in after the time point t ₂ are different in the same area 24 ₁ . Memorized in. Therefore, when the repetitive data is next input to the analog terminal 21 and the data is similarly fetched, the first added data is cumulatively added to the data of the first stored portion of the data memory area 24 _1. Is done. That is, in the memory, the data of the cumulative addition portion of the corresponding sampling points is cumulatively added for each input data.

As described above, in the example of FIGS. 1 and 2, four times as much data is collected as in the conventional data collection,
When collecting the same number of data, the data collection time will be 1/4. In the case of collecting data at the same time, data with a higher S / N ratio can be obtained. In addition, in the case of cumulative addition, it takes a considerable time to perform the operation of reading from the memory 24, adding with new data, and writing to the same address, but in the adder 23, for example, as shown in FIG. With the configuration, the addition results are cumulatively added one after another, and in this example, four addition results may be input to the second latch.
The processing for one group, that is, the cumulative addition to the memory 24 may be performed within the time of T _u , and this can be performed by taking a relatively long time. Moreover, many sample values can be taken by effectively utilizing the capabilities of each AD converter.

When the backscatter data of the optical fiber is measured using this device, its distance range, distance span, distance resolution,
The number of multiple additions, that is, the number n of the first latches to be added in FIG. 1, n = 4 in FIG. 1, n = 0 in the past, and the time required for processing when the number of input data is 2 ¹⁶ This is as shown in FIG. For example, the distance range is 10
When the distance resolution is 50 m when the distance span is 100 km and the distance span is 0 km, the measurement time of 65.5 seconds was conventionally required, but in the present invention, four first latches are added as in the embodiment of FIG. This will take 16.4 seconds. It will be appreciated that the measurement time according to the invention is short.

The number of the first latches to be added is not limited to 4 and can be appropriately selected. If the distance resolution is relatively low compared to the AD converter's capability, that is, if it is large, the number of additions can be increased, the effect is great, but if the distance resolution is high and measurement is performed for each short distance, AD conversion is performed. Since the range resolution approaches the capacity of the vessel, the effect of the present invention is reduced. Note that the present invention is not limited to the measurement of backscattering, in general, the input signal is repeated, and the repeated input signal is sampled as a digital value, and the corresponding sampling time portion is cumulatively added to S / It can be generally applied to improve the N ratio.

[Advantages of the Invention] As described above, according to the present invention, the ability of the AD converter can be effectively utilized, and therefore, the measurement can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the repetitive data collecting device according to the present invention, FIG. 2 is a time chart used for explaining the operation thereof, and FIG. 3 is a diagram showing an example of the adder thereof.
FIG. 5 is a diagram showing an example of data showing the effect of the present invention, and FIG. 5 is a diagram showing data collection by a conventional device.

Claims (1)

[Claims] 1. An AD converter sequentially samples data that changes substantially continuously and is repeatedly input at a cycle corresponding to a desired resolution, converts the data into digital values, and adds digital data at respective corresponding sampling points. In the repetitive data acquisition device, the sampling cycle of the AD converter is selected to be 1 / n (n is an integer of 2 or more) of the cycle corresponding to the resolution, and the digital values from the AD converter are sequentially held. First done
The latch and the first latch are provided for every n consecutive n.
P (p is an integer of 2 or more) adders for adding the contents of the first latches, p second latches for holding the addition results of the p adders, and the p A memory for accumulating the contents of the second latch of the second latch, holding the first latch every time the input data is repeated, adding by the adder, holding the addition result in the second latch, the second latch A repetitive data collecting device, which repeats the cumulative addition of the contents of the above to the corresponding one in the memory.