JPH09184880A - Forest tree height measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the heights of forest trees exactly, easily and surely by sing a measuring technique of interference synthetic aperture radar. SOLUTION: A short wave length interference synthetic aperture radar system (A) transmits a transmission wave WST of short wave length reflective at the topmost leave part of forest trees from a transmission/reception antenna 1, receives the reflecting wave WSR with the transmission/reception antenna 1 and a reception antenna 2 and obtains the information of the height of the topmost of the forest trees with a signal processor 11 based on the phase difference of the received signal from the receiver 7. A long wave length interference synthetic aperture radar system (B) transmits a transmission wave WLT of long wave length reflective at the bottom ground part of forest trees from a transmission/reception antenna 3 together with a transmission wave WST of short wave length, receives the reflecting wave WLR with the transmission/ reception antenna 3 and a reception antenna 4 and obtains the information of the height of the ground with a signal processor 11 based on the phase difference of the received signal from the receiver 7. From these obtained information of heights of the topmost of the forest trees and the bottom ground, the heights of the forest trees are calculated with the signal processor 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terrain height information (DEM: Digital El
The present invention relates to a forest tree height measuring device that measures the height of a forest tree by using a data processing technique of an interference synthetic aperture radar (INSAR) that obtains contour data or contour data.

[0002]

2. Description of the Related Art Conventionally, the height of forest trees has been measured on the ground using a known laser measuring instrument. In this case, the user goes out to the vicinity of the tree to be measured, installs a laser measuring device, and performs the measurement.

With respect to such a measurement of the height of a tree, Japanese Patent Laid-Open Publication No. Hei 4-248307 discloses a "radar device for measuring the distance between transmission lines". This conventional example measures a distance between a power transmission line and a survey area having a tree having a trouble. Hover a helicopter over the study area,
A radar wave is transmitted from the antenna of the installed transmission line separation distance measurement radar device to the survey area where there is a hindrance, the tree is identified based on the reflection time difference, and the separation distance from any conductor of the transmission line is measured. ing.

[0004]

However, according to the above-mentioned publications, it is possible to easily measure the depth of a mountain or the like where it is difficult to perform manual measurement from the ground by using a helicopter, and at the same time to use a forest or the like. Although the measurement can be easily performed over a wide area, the distance between the helicopter and the ground is not measured, and the height of the forest tree cannot be measured.

The present invention has been made to solve the above-mentioned problems in the prior art, and has disclosed an interference synthetic aperture radar (IN).
Provided is a forest tree height measuring device capable of accurately, easily and surely measuring the height of a forest tree using a measurement technique of SAR).

[0006]

Means for Solving the Problems To achieve the above object, an invention according to claim 1 is a forest tree height measuring device mounted on a flying object for measuring the height of forest trees. A radio wave of a short wavelength reflected at the top leaf portion of the forest is transmitted from the transmission / reception antenna, and the height of the top of the forest tree is determined based on the phase difference between the reception signals received by the transmission / reception antenna and the reception antenna. A first interferometric synthetic aperture radar system for obtaining depth information, a radio wave of a long wavelength reflected on the ground at the bottom of the forest tree at the same time as the first interferometric synthetic aperture radar system, transmitted from a transmitting / receiving antenna, and the reflected wave And a second interference synthetic aperture radar system that obtains height information of the bottom of the forest tree from the phase difference received by the transmitting / receiving antenna and the receiving antenna, and a forest tree measured by the first interference synthetic aperture radar system. Upper part And height information, there is a structure and a calculation processing means for calculating the height of forest trees and a height information of the ground at the bottom of forest trees has been measured by the second interference synthetic aperture radar system.

According to a second aspect of the present invention, there is provided a forest tree height measuring apparatus, wherein each of the first and second interference synthetic aperture radar systems comprises:
A transmission unit for transmitting a pulse signal of a chirp wave, a switching unit for transmitting and receiving a pulse signal from the transmission unit, or a transmission and reception antenna for outputting a reception signal of a reflected wave, and a pulse signal from the transmission unit And a circulator for transmitting the reflected wave received signal received by the receiving antenna through the switching unit, and a receiving unit that processes the received signal received by the transmitting / receiving antenna and the receiving antenna from the switching unit. And a height information processing unit that obtains the height information of the top of the forest tree from the phase difference between the two received signals output by the reception unit, or the height information of the ground at the bottom of the forest tree. .

According to a third aspect of the present invention, there is provided a forest tree height measuring device, comprising: a recording unit for recording the height data of the forest tree calculated by the calculation processing unit on a recording medium; and the height data stored in the storage medium on a map. And a map data processing means for displaying the map data.

According to a fourth aspect of the present invention, there is provided a forest tree height measuring device including self absolute position measuring means for measuring a self absolute position, wherein the self absolute position data measured by the self absolute position measuring means is used as forest tree height data. At the same time, the recording means stores the information in a storage medium.

The forest tree height measuring apparatus according to a fifth aspect of the present invention is configured to use a global azimuth measuring system and / or an inertial navigation system as the self-absolute position measuring means.

According to the forest tree height measuring apparatus of the present invention having the above-mentioned structure, the short wavelength of light reflected from the uppermost leaf portion of the forest tree to be measured from a flying object such as an aircraft or a satellite. The height information of the top of the forest tree is obtained based on the phase difference between the received signals transmitted by the radio waves and received by the two antennas. At the same time, a long wavelength radio wave reflected on the bottom of the forest tree is transmitted, and the height information of the bottom of the forest tree is obtained from the phase difference received by the two antennas, and the obtained forest tree is obtained. The height of the forest tree is calculated from the height information of the top of the tree and the height information of the ground at the bottom of the forest tree. Therefore, the height of the forest tree can be accurately, easily and reliably measured using the interference synthetic aperture radar (INSAR) measurement technique.

According to a third aspect of the present invention, there is provided a forest tree height measuring apparatus which includes a global azimuth measurement system (GPS) and an inertial navigation system (IN) in accordance with measured forest tree height data.
Since the self-absolute position data measured in S) is stored and represented on the map, the absolute position when the height of the forest tree is measured, that is, the position of the measurement point on the map is reliably determined. Become like

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a forest tree height measuring apparatus according to the present invention will be described in detail with reference to the drawings. FIG.
1 is a block diagram showing a configuration of an embodiment of a forest tree height measuring device according to the present invention. The example shown in FIG. 1 is mounted on an aircraft or satellite projectile, and uses an interference synthetic aperture radar (INSA).
The height of the forest tree in the measurement target area is measured by applying the measurement technique of R).

In order to measure the height up to the top leaf portion of the forest tree, a short wavelength interference synthetic aperture radar system A having a short wavelength, for example, transmitting and receiving in the X band, and a bottom portion of the forest tree In order to measure the height to the ground, a long-wavelength interference synthetic aperture radar system B having a longer wavelength than the X band, for example, transmitting and receiving in the P band is provided.

The short-wavelength interference synthetic aperture radar system A radiates the transmission wave WST in the X-band and transmits the radiated transmission wave WST.
Reflected wave WSR reflected from the top leaf of forest tree at ST
Transmitting and receiving antenna 1 for receiving
And a receiving antenna 2 for receiving the reflected wave WSR.

Further, the long-wavelength interference synthetic aperture radar system B has a transmission wave W in the P-band, longer in wavelength than the X-band.
The transmitting and receiving antenna 3 for radiating LT and receiving the reflected wave WLR in which the radiated transmission wave WLT is reflected on the bottom ground of the forest tree, and the receiving antenna 4 for receiving the reflected wave WLR
Are provided.

A switching unit 5 for switching between transmission and reception of the transmitting / receiving antenna 1 in the short wavelength interference synthetic aperture radar system A.
And a switching unit 6 for switching between transmission and reception of the transmission / reception antenna 3 in the long wavelength interference synthetic aperture radar system B.

Further, the reflected wave WSR at the transmitting / receiving antenna 1 and the antenna 2 in the short wavelength interference synthetic aperture radar system A
And a transmitting unit 8 for transmitting a linear frequency modulated wave (chirp signal) which is a transmission wave WST.

Further, a receiving unit 9 for performing processing such as frequency conversion and detection on the received signals from the transmitting and receiving antennas 3 and 4 in the long wavelength interference synthetic aperture radar system B and outputting the signals, and a pulse signal of the transmitted wave WLT. Sending unit 10 for sending
And a signal processing unit 11 for calculating the height of the forest tree and taking in and outputting the absolute position data. The signal processing unit 11 includes a height information processing circuit for obtaining height information of the top of the forest tree in the short wavelength interference synthetic aperture radar system A, and a bottom information processing circuit in the long wavelength interference synthetic aperture radar system B. And a calculation processing circuit that calculates the height of the forest tree from the two pieces of height information.

Further, the height data of the forest tree calculated by the signal processing unit 11 and the absolute position data thereof are stored in, for example, a magnetic recording medium, and the recording unit 12 is installed on the ground and the data of the magnetic recording medium is stored. A data processing device 13 for performing processing such as writing height data of a forest tree measured on a map based on the data, and a short-wavelength interference synthetic aperture radar system A
And an operation control unit 14 for controlling transmission / reception operations and the like in the long-wavelength interference synthetic aperture radar system B.

Further, the receiving antenna 2 in the short wavelength interference synthetic aperture radar system A is connected, and the circulator 15 for transmitting the chirp signal from the transmitting unit 8 and the receiving antenna 4 in the long wavelength interference synthetic aperture radar system B are connected. A circulator 16 that is connected and transmits a chirp signal from the transmission unit 10 is provided. Further, GPS radio waves Wa, Wb, Wc, W from GPS satellites in the sky
d and a self-absolute position (latitude,
GPS that outputs (longitude, altitude) data to the signal processing unit 11
And a receiver 21.

Next, the operation of this embodiment will be described. In the short-wavelength interference synthetic aperture radar system A, an X-band transmission signal output by the transmission unit 8 from above the forest tree in the measurement target area is transmitted as a transmission wave WST from the transmission / reception antenna 1 through the circulator 15 and the switching unit 5. The transmission wave WST is a chirp wave, and its pulse frequency is determined so that the reflected wave from the ground and the transmission wave are not simultaneously transmitted and received by the transmission / reception antenna 1. The switching unit 5 switches after the transmission so that the transmitting / receiving antenna 1 and the circulator 15
The received signal from the receiving antenna 2 through the receiver is input to the receiving unit 7. That is, a reception signal of the reflected wave WSR, which is a reflection of the transmitted wave WST at the uppermost leaf portion of the forest tree, is input to the receiving unit 7.

Similarly, in the long-wavelength interference synthetic aperture radar system B, a transmission signal in the P-band having a long wavelength output from the transmission unit 10 is transmitted from the transmission / reception antenna 3 via the circulator 16 and the switching unit 6 as a transmission wave WLT. From above the forest trees. After this transmission, the switching unit 6 switches, and the reception signal from the reception antenna 4 via the transmission / reception antenna 3 and the circulator 16 is input to the reception unit 9. That is, a reception signal of the reflected wave WLR in which the transmitted wave WLT is reflected on the ground at the bottom of the forest tree is input to the receiving unit 9.

In this case, the short wavelength interference synthetic aperture radar system A
The transmission in the long wavelength interference synthetic aperture radar system B is performed simultaneously under the control of the operation control unit 14. That is, the transmission wave WST having the short wavelength and the transmission wave WLT having the long wavelength are simultaneously transmitted to the forest trees in the same measurement target area, and the height of the forest trees is measured. Then, the receiving unit 7 performs frequency conversion, detection, and the like on the received signal of the reflected wave WSR, and outputs the signal to the signal processing unit 11. The receiving unit 9 also performs frequency conversion, detection, and the like on the received signal of the reflected wave WLR and outputs the signal to the signal processing unit 11.

In the GPS antenna 20, the sky 4
GPS radio waves Wa to Wd from more than one GPS satellites are received, and the received signals are input to the GPS receiver 21. The GPS receiver 21 calculates its own absolute position (latitude, longitude, altitude) data from the received signal, and
Output to The signal processing unit 11 calculates the height of the forest tree in the measurement target area and sends it to the recording unit 12 together with the GPS receiver 21's own absolute position data.

FIG. 2 is a diagram for explaining the principle of measurement when obtaining height information (DEM) of a measurement target area (terrain and contour lines) using an interference synthetic aperture radar. In FIG.
When the transmission wave WST (WLT) is transmitted from the transmitting / receiving antenna 1 (3) toward the target forest tree H, this transmission wave WST (WLT) is transmitted.
The ST (WLT) is reflected, and is simultaneously received by the transmitting / receiving antenna 1 (3) and the receiving antenna 2 (4) arranged at different heights. In this case, a phase difference occurs between the received signals of the reflected waves WSR (WLR) received by the two antennas. This phase difference φ is given by the following equation 1 with respect to the measurement target region T.

Φ = 2π / λ (L−La) = 2π / λ (dx · sin θ−dy · cos θ) (1) λ: wavelength dx, dy: distance between horizontal and vertical components between two antennas L , La: Distance between two antennas and measurement target area T θ: Off nadir angle

Therefore, when the position of the measurement target area T changes, two antennas, ie, the transmitting and receiving antenna 1
The distances L and La between (3) and the measurement target area T between the receiving antenna 2 (4) change, and the phase difference φ
Changes, resulting in interference fringes. Here, when the measurement target region T is a plane, the fringes are parallel to the flight direction, but when the measurement target region T has undulations, the fringes are curved interference fringes. The interference fringes include height information as well as distance information. By subtracting parallel interference fringes when the measurement target area T is assumed to be a plane from this curve, a phase difference image including only height information of the measurement target area T can be obtained. The height of the forest tree in the measurement target region T is calculated using such an interference synthetic aperture radar measurement technique (data processing technique).

FIG. 3 is a diagram for explaining the reflection state of the transmitted wave WST (WLT) on a forest tree. As shown in FIG. 3 (a), the transmission wave WST in the X-band having a short wavelength radiated from the transmitting / receiving antenna 1 is reflected at the uppermost leaf portion, and the reflected wave WSR is simultaneously transmitted to the transmitting / receiving antenna 1 and the receiving antenna 2. Received. Also, as shown in FIG. 3B, the transmission wave W in the P band having a long wavelength radiated from the transmission / reception antenna 3.
LT reflects on the bottom ground of the forest tree, and its reflected wave WLR
Are simultaneously received by the transmitting / receiving antenna 3 and the receiving antenna 4.

The phase difference signal of the received signal is transmitted from the receiving unit 7 in the short wavelength interference synthetic aperture radar system A and the receiving unit 9 in the long wavelength interference synthetic aperture radar system B to the signal processing unit 1.
1 is input. The signal processing unit 11 performs the data processing described with reference to FIG. 2 and (Equation 1) to calculate the respective heights of the top leaf portion of the forest tree and the ground at the bottom of the forest tree.

That is, the short wavelength interference synthetic aperture radar system A
Transmits the X-band transmission wave WST having a short wavelength reflected at the top leaf portion of the forest tree, and this reflected wave WSR
Is calculated from the height Ha of the uppermost leaf portion of the forest tree. Further, by using the long wavelength interference synthetic aperture radar system B,
The transmission wave WLT in the P-band having a long wavelength reflected on the ground at the bottom of the forest tree is radiated, and the height Hb of the ground at the bottom of the forest tree is calculated from the reflected wave WLR. Signal processing unit 1
In step 1, the height Hb of the lowermost ground of the forest tree is subtracted from the height Ha of the uppermost leaf portion of the forest tree to calculate the height of the forest tree.

The signal processing unit 11 fetches the absolute position data from the GPS receiver 21 together with the measured height data of the forest trees and sends it to the recording unit 12, where it is stored. Thereafter, the magnetic recording medium recorded by the recording unit 12 is processed by the ground data processing device 13. For example, data processing for writing height data of the measured forest trees on a map is performed.

Although the self-absolute position is measured using the GPS receiver 21 in this embodiment, another system may be used. For example, the inertial navigation system (IN
Data such as S) may be used.

The signal processing unit 11 obtains the height information of the top and bottom of the forest tree and performs data processing for calculating the height of the forest tree. A signal processing unit is separately provided for each of the synthetic aperture radar systems A and B so that the height information of the top and bottom of the forest tree is obtained, respectively. You may make it calculate it. In other words, using two interferometric synthetic aperture radars, the heights of the forest trees at the top and bottom of the forest trees measured at short wavelengths and long wavelengths, respectively, are used to measure the height of the forest trees using an image processing device. May be calculated.

[0035]

As is apparent from the above description, according to the forest tree height measuring apparatus of the first and third aspects of the present invention, the reflected wave of the short-wavelength radio wave transmitted from the flying object to the forest tree is converted into two waves. Based on the phase difference of the received signal received by the antenna,
While obtaining the height information of the top of the forest tree, the height information of the ground at the bottom of the forest tree based on the phase difference between the reflected signals of the long-wave radio waves transmitted simultaneously and received by the two antennas. It has gained. Since the height of the forest tree is calculated from these two information, the interference synthetic aperture radar (INS)
Using the AR) measurement technique, the height of forest trees can be accurately, easily and reliably measured.

According to the forest tree height measuring device of the third to fifth aspects, the global azimuth measurement system (GPS) and the inertial navigation system (IN) are used in conjunction with the measured forest tree height data.
Since the self-absolute position data measured in S) is stored and displayed on the map, the absolute position when the height of the forest tree is measured, that is, the position of the measurement point on the map can be reliably determined. Become like

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a forest tree height measuring device according to the present invention.

FIG. 2 is a diagram for explaining a measurement principle when obtaining height information of a measurement target region using the interference synthetic aperture radar in the embodiment.

FIG. 3 is a diagram illustrating a reflection state of a transmission wave on a forest tree in the embodiment. (A) is a figure which shows the reflection state in a forest tree when a wavelength is long. (B) is a figure which shows the reflection state in a forest tree when a wavelength is short.

[Explanation of symbols]

 A short-wavelength interference synthetic aperture radar system B long-wavelength interference synthetic aperture radar system 1,3 transmitting / receiving antenna 2,4 receiving antenna 5,6 switching unit 7,9 receiving unit 8,10 transmitting unit 11 signal processing unit 12 recording unit 13 data Processing unit 21 GPS receiver

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01S 13/90 G01S 13/90

Claims (5)

[Claims] 1. A forest tree height measuring device mounted on a flying object to measure the height of a forest tree, wherein a radio wave of a short wavelength reflected at a top leaf portion of the forest tree is transmitted from a transmission / reception antenna. And a first interference synthetic aperture radar system that obtains height information of the top of a forest tree based on a phase difference between reception signals received by the transmission / reception antenna and the reception antenna from the reflected wave; At the same time as the interference synthetic aperture radar system, a long-wave radio wave reflected on the ground at the bottom of the forest tree is transmitted from the transmitting / receiving antenna, and the reflected wave is transmitted to the forest tree from the phase difference received by the transmitting / receiving antenna and the receiving antenna. A second interference synthetic aperture radar system for obtaining height information of a lower ground, a height information of a top of a forest tree measured by the first interference synthetic aperture radar system, and a second interference synthetic aperture radar system so And a calculation processing means for calculating the height of the forest tree from the measured height information of the ground at the bottom of the forest tree. 2. A transmitting section for transmitting a chirp pulse signal to each of the first and second interference synthetic aperture radar systems, and a pulse signal from the transmitting section or reception of a reflected wave. A switching unit that switches between transmission and reception of a transmission / reception antenna to output a signal; and a pulse signal from the transmission unit is transmitted to the switching unit, and a reception signal of a reflected wave received by a reception antenna is transmitted through the switching unit. A circulator for processing a reception signal received by a transmission / reception antenna and a reception antenna from the switching unit; and a height information of a top of a forest tree from a phase difference between the two reception signals output by the reception unit. The forest tree height measuring device according to claim 1, further comprising: or a height information processing unit that obtains height information of the lowest ground of the forest tree. 3. A recording means for recording height data of a forest tree calculated by the calculation processing means on a recording medium, and a map data processing means for displaying the height data stored in the storage medium on a map. The forest tree height measuring device according to claim 1 provided with. 4. A self-absolute position measuring means for measuring a self-absolute position is provided, and self-absolute position data measured by the self-absolute position measuring means is stored in a storage medium by a recording means together with height data of a forest tree. The forest tree height measuring device according to claim 3, wherein: 5. The forest tree height measuring device according to claim 4, wherein a global azimuth measuring system and / or an inertial navigation system is used as said self absolute position measuring means.