JPH04147037A - Device for measuring density of object floating in space - Google Patents

Abstract

PURPOSE:To obtain an accurate measurement result constantly by performing relative evaluation of average power in reference to a detected maximum power from received power which is obtained by collecting time-series waves scattered to the rear. CONSTITUTION:A light-emitting element 6 is driven through a timing clock generation circuit 8 and a transmission circuit 7 and pulse-shaped infrared rays from the element 6 are emitted to a target W through a transparent protection plate 3. Then, scattering light which is scattered by the target W is received by a light-receiving element 9 through a transparent protection plate 2 and an optical lens 4. Reception voltage for each pulse hit from the element 9 is integrated at a reception circuit 10 and a reception pulse integration voltage V (V1 - Vn) which is integrated for each specified cycle is sampling-output. In a maximum value detection circuit 11, a maximum reception pulse integration voltage value Vm out of an integration voltage V is detected and an average value Va of the integration voltage V is detected at an average value detection circuit 12. Then, a ratio Q with the average value Va is obtained in a division circuit 13 in reference to a voltage value Vm and a measurement value is converted to a decibel value in a logarithmic conversion circuit 14.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for measuring the density of objects floating in space, and more specifically, it emits time-series pulsed energy waves into a measurement space to detect the density of objects floating in the space. The present invention relates to a density measuring device for objects floating in space that measures target density by receiving backscattered waves.

[Prior art 1] When a time-series pulsed energy wave is emitted into a measurement space and backscattered waves from a target such as rain or snow floating in the measurement space are received, the average value of the received pulse integrated voltage is equal to the target density. It is known that it responds to changes over time. Therefore, in the past, the average value of this received pulse integrated voltage was directly calculated,
Alternatively, rainfall intensity, etc., was measured by counting this average value or the time span that continued for a certain period of time. That is, conventionally, target density was measured based on the absolute value of received data.

By the way, this type of device transmits/transmits pulsed energy waves.
It has a receiving section, and this part is exposed to the outside, so if it gets dirty or damaged, the transmitted/received signal will be attenuated, and conventional evaluation using absolute values will cause measurement errors. Put it away. For example, if the light pulse emitting/receiving surface becomes dirty, this will lower the level of received backscattered waves, causing conventional devices to measure a lower amount of precipitation than the correct value. Moreover, as such contamination or damage progresses, the received light level further decreases, and the measurement range of the device becomes extremely narrow.

Also, is it generally known that the received power of backscattered waves from a target is controlled by the scattering coefficient (mainly dielectric constant) of particles?
Even if targets have the same particle size and particle density, if their scattering coefficients differ, the measured values of the target densities will differ.

[Problems to be Solved by the Invention] Conventional density measurement of objects floating in space as described above is performed as described above, and since the target density is measured using the absolute value of the received power, the measured value is transmitted/received. This included errors due to soiling of the parts and differences in the scattering coefficients of the target particles.

This invention was made to solve this problem, and even if the energy wave transmitting/receiving section is contaminated or damaged,
Another object of the present invention is to provide a density measuring device for objects floating in space that can always accurately measure target density even if the scattering coefficients of target particles differ.

[Means for Solving the Problems] A device for measuring the density of objects floating in space according to the present invention emits time-series pulsed energy waves into a measurement space and receives backscattered waves from a target floating in the space. In a space-floating object density measuring device that measures target density at a maximum power detection means for detecting, an average power detection means for detecting the average power of the n received powers, and a target density evaluation means for relatively evaluating the detected average power with reference to the detected maximum power. Be prepared.

[Operation 1] The device for measuring the density of objects floating in space according to the present invention collects time-series backscattered waves for a certain period of time and calculates n received power values (
P, ), the maximum power (Po) and average power (P8) are determined based on these received power values (P,), and the average power is calculated based on the obtained maximum power (P, n). It is a relative evaluation of (P6), and by this,
For example, even if the received power value (P,) is attenuated by snow accretion or drops on the transmitting/receiving section, the maximum power (P, , ) and the average power (P8) are attenuated to the same extent. So,
By performing a relative evaluation (for example, taking a ratio), the effects of attenuation can be canceled out.

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a snowfall intensity meter according to an embodiment of the present invention. In the figure, (1) is the main body of the snowfall intensity meter, (2), (3)
) is a transparent protective plate, (4) and (5) are optical lenses, (6
) is an infrared light emitting element, (7) is a transmitting circuit, (8) is a timing clock generation circuit, (9) is an infrared light receiving element, (10) is a receiving circuit, (11) is a maximum value detection circuit, (
12) is an average value detection circuit, (13) is a division circuit, (14)
) is a logarithmic conversion circuit.

Further, the area surrounded by diagonal lines in the figure is the field of view of this snowfall intensity meter, and (W) is the snowfall (target).

Next, the operation will be explained. FIG. 2 is an operation timing chart of the device shown in FIG.
A transmission pulse of H2 is generated for a period of time (tl), and this is repeated for a predetermined time (to). Transmission circuit (
7) drives a light emitting element (6) according to the transmission pulse signal, and the pulsed infrared light from this light emitting element (6) passes through the optical lens (5) and the transparent protection plate (3) to the target (W).
) is radiated towards.

On the other hand, the backscattered light scattered by the target (W) is received by the light receiving element (9) through the transparent protection plate (2) and the optical lens (4). This received wave detects individual particles (snowfall) within the field of view.
Since it is a composite wave of reflected waves from each particle, the phase of the reflected wave from each particle changes for each pulse hit due to the random arrangement of snowfall and the movement of each particle, and the received power (that is, received voltage) changes from moment to moment. fluctuate. Therefore, the receiving circuit (1
0) integrates the received voltage for each pulse hit, and
At every predetermined period (t2), received pulse integrated voltages (vl) to (Vo) obtained by integrating the received voltage in that section are sampled and output.

Figure 3 shows the received pulse integrated voltage (vl) obtained in this way.
-(V,) are arranged in descending order, and here they are shown as the received pulse integrated voltage (4) or the maximum voltage (V,).

FIG. 4 is a graphical representation of the situation of FIG. 3 in the form of envelopes, in which a plurality of envelopes measured for different target densities are shown. In the figure, (V,,) indicates the envelope when the target density is the smallest, and when the average voltage of the received pulse integrated voltages (■1) to (V,) at this time is determined, (
V, ). Similarly, (V, □) indicates the envelope when the target density is slightly larger than the above, and the average voltage at this time is (V, □). Furthermore, (■a5) shows the envelope when the target density is the highest, and the average voltage at this time is (V as). Thus, each average voltage has (V-+) < (V, □) < (V-3) <
As described above, there is a relationship of (V, 4) < (V, s), and the target density can be measured by finding this average voltage.

By the way, if the received pulse integrated voltage is collected over a predetermined period of time (to) as in this embodiment, it is found that every wrapped cotton has a substantially constant maximum received pulse integrated voltage (~',,,). notice.

Generally, the received power (P) of backscattered light is (however, K:
Optical constant, 0 Particle scattering cross section, D, particle density in space, R: Distance from projector to target) ) is constant, the peak power (P, . . . ) caused by a large scattering cross section (a) or a small distance (R) is always included.

Returning to FIG. 1, the maximum value detection circuit (11) detects the maximum received pulse integrated voltage value (Vo) from among the received pulse integrated voltages (vl) to (V, ). On the other hand, the average value detection circuit (12) detects the received pulse integrated voltage (V, ) ~ (V,
The average value (V, ) of ) is detected by. Then, the division circuit (13) performs a relative evaluation of this average value (V,) using the maximum received pulse integrated voltage value (vl) as a reference, and calculates the ratio of these values according to ) is converted into a decibel value according to S = 201'og Q, where S = 101'ogQ when the measured value (Q) is a power ratio.

Here, if the transparent protection plates (2) and (3) become dirty, the received pulse integrated voltages (Vl) to (Vn) will also attenuate accordingly, but this will now be the basis for calculating the average value (V,). The average attenuation coefficient at the time of detection of the received pulse integrated voltage (■1) ~ (V,) is (21 + attenuation at the time of detection of the received pulse integrated voltage (V,) corresponding to the maximum received pulse integrated voltage value (■.) If the coefficient is a2, then the 11 constant straightness (S) is [5 is,
However, compared to the progress of contamination, the received pulse integrated voltage (v
If the collection time (to ) of l) is sufficiently short, a1 丑α2
According to this embodiment, it is a transparent protection plate (2).

Even if dirt occurs in (3), the attenuation due to this is canceled out by the relationship between the denominator and numerator, so that no error occurs in the measurement results.

Furthermore, this allows the effective measurement range, which was conventionally about 50% of the full scale, to be expanded to about 90%.

In addition, according to the present invention, since a relative evaluation is performed between (■8) and (V, , ), accurate measurement results that are faithful to the target density can be obtained even if the scattering coefficient of the target differs depending on the installation location of the device. is obtained.

Furthermore, in conventional rainfall radars and snow radars that use electromagnetic waves, it is necessary to estimate a reflection coefficient called a radar reflection factor to convert reflected power into precipitation intensity.
If there is an estimation error in this, it will lead to an error in the measurement of precipitation intensity, but if the present invention is applied, the reflection coefficient will not be involved, so there is an advantage that the measurement accuracy can be improved.

Although a snowfall intensity meter is shown in the above embodiment, a precipitation intensity meter or other spatially floating object density measuring device may be used.

In addition, although the above embodiments used infrared rays, the present invention is applicable to turbidity meters that use light waves, radar rain/snow needles that use electromagnetic waves, or devices that non-contactly measure floating objects in space using sound waves. can also be applied.

[Effects of the Invention] As explained above, this invention uses the detected maximum power as a reference to evaluate the average power relative to it, so it is always accurate even if the transmitting/receiving section is contaminated or the scattering coefficient of the target is different. In addition to obtaining accurate measurement results, it also has the effect of widening (maintaining) the effective range of measurement.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a snowfall intensity meter according to an embodiment of the present invention, Fig. 2 is an operation timing chart of the device shown in Fig. 1, and Fig. 3 shows received pulse integrated voltages (■, ) to (Vn) in descending order. The arranged graph diagram, Figure 4, shows the average voltage (V, ) ~ (V,
5) is a graph diagram showing, as an envelope, a sequence of corresponding received pulse integrated voltages using 5) as a parameter. (1) is the main body, (2), (3) are transparent protective plates, (4),
(5) is an optical lens, (6) is an infrared light emitting element, (7
) is a transmission circuit, (8) is a timing clock generation circuit,
(9) is an infrared light receiving element, (10) is a receiving circuit, (11)
) is the maximum value detection circuit, (I2) is the average value detection circuit, (I
3) is\

Claims (1)

[Scope of Claims] A density measuring device for a space-floating object that measures target density by emitting time-series pulsed energy waves into a measurement space and receiving backscattered waves from a target floating in the space, comprising: receiving means for collecting backscattered waves of the sequence for a predetermined period of time to obtain n received powers; maximum power detecting means for detecting the maximum power from among the n received powers; and an average of the n received powers. An apparatus for measuring the density of objects floating in space, comprising: average power detection means for detecting power; and target density evaluation means for relatively evaluating the detected average power with reference to the detected maximum power.