JP2015194494A - Position-determination method and position-determination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To swiftly and accurately determine position of a target.SOLUTION: The position-determination apparatus: sets a transmission trigger signal, an orientation direction and a transmission time on a transmission wave; generates the transmission wave according to the transmission trigger signal; radiates a transmission wave to the space in an orientation direction; receives a reflection wave from the target as a reception signal; detects a propagation time required for the radio wave to reciprocate between an antenna 4 and the target from the reception time and the transmission time of the received signal; stores the refractive index spatial distribution of the atmosphere in a space to which the radiation is made by the antenna 4; and determines the position of the target based on the propagation time, the orientation direction and the refractive index spatial distribution.

Description

  The present invention relates to a position locating method and a position locating apparatus for locating a target position from observation results.

  When a remote target such as an aircraft or an artificial satellite is observed using a radar placed on the ground, a radio wave reciprocating between the radar and the target propagates in the atmosphere for a relatively long distance. When the refractive index of the atmosphere is constant (uniform distribution) regardless of the altitude from the ground surface, the radio waves travel straight, so the propagation time for the radio waves to travel back and forth between the antenna and the target, and the antenna pointing direction (= Radiation direction of radio waves), the position of the target can be accurately determined by simple geometry. The orientation accuracy in this case is determined by the measurement accuracy of the radio wave propagation time and the pointing accuracy of the antenna.

このように、標準的な大気においては、屈折指数Ｎは高度の増加とともに指数関数的に単調減少し、高度およそ５０ｋｍ以上では０（ｎ＝１：真空）となることがわかる。 However, as is well known, the refractive index spatial distribution in the atmosphere is not uniform, varies depending on the position, and changes particularly in the altitude direction. Since the refractive index of the atmosphere is determined by three meteorological factors of air temperature, atmospheric pressure, and water vapor pressure, it changes from moment to moment according to weather conditions. As is often the case, it decreases exponentially with increasing altitude. An atmospheric refractive index spatial distribution model having such characteristics is called a standard atmospheric model. As an example of the standard atmospheric model, the refractive index spatial distribution of the atmospheric air in the mid-latitude region shown in Non-Patent Document 2 is shown in FIG. In FIG. 10, the vertical axis represents the height from the ground surface, and the horizontal axis represents the refractive index. The relationship between the refractive index N and the refractive index n (definition of the refractive index N) is given by the following equation (1).

Thus, in the standard atmosphere, it can be seen that the refractive index N decreases monotonically exponentially with an increase in altitude and becomes 0 (n = 1: vacuum) at an altitude of about 50 km or more.

As described above, since the refractive index in the atmosphere is not uniform and has a distribution, radio waves propagating in the atmosphere cannot travel straight, and are refracted according to Fermat's principle. For this reason, in order to increase the positioning accuracy of a target located far away, refraction of radio waves due to the refractive index spatial distribution of the atmosphere must be considered.
For example, the method of Patent Document 1 is known as a target location method that takes into account the refraction of radio waves. In this method, radio wave refraction is corrected using an equivalent earth radius KR obtained by multiplying an actual earth radius R by an equivalent earth radius coefficient K (constant).

JP 2002-286836 A

Recommendation ITU-R P.453-10, The radio refractive index: its formula and refractivity data. Recommendation ITU-R P.835-5, Reference standard atmospheres.

なお、ｈは地表面からの高さであり、ｎ（ｈ）は高度ｈにおける屈折率である。上式（２）からわかるように、屈折率が高度に対して線形に変化する場合は、等価地球半径係数Ｋは高度に依存しない定数となり、等価地球上では伝搬光路が直線となる。しかしながら、非特許文献１，２で示されているように、実際の屈折率高度分布は非線形であるため、Ｋは高度の関数となる。このため、等価地球を用いる方法では、大気による電波屈折の補正に大きな誤差が生じる。 Here, the equivalent earth radius coefficient K is defined by the following equation (2).

Note that h is a height from the ground surface, and n (h) is a refractive index at an altitude h. As can be seen from the above equation (2), when the refractive index changes linearly with respect to the altitude, the equivalent earth radius coefficient K is a constant independent of the altitude, and the propagation optical path is a straight line on the equivalent earth. However, as shown in Non-Patent Documents 1 and 2, since the actual refractive index height distribution is non-linear, K is a function of altitude. For this reason, in the method using the equivalent earth, a large error occurs in correction of radio wave refraction by the atmosphere.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a position locating method and a position locating apparatus capable of locating a target position at high speed and with high accuracy.

  The position locating method according to the present invention includes a setting step for setting a transmission trigger signal, a directivity direction and a transmission time for a transmission wave, a transmission wave generating step for generating a transmission wave according to the transmission trigger signal set in the setting step, and an antenna. The transmission / reception step for radiating the transmission wave generated in the transmission wave generation step toward the space and receiving the reflected wave from the target as the reception signal in the directivity direction set in the setting step, and the reception time of the reception signal in the transmission / reception step And a transmission time detection step for detecting a propagation time for a radio wave to reciprocate between the antenna and the target from the transmission time set in the setting step, and a memory for storing the refractive index spatial distribution of the atmosphere in the space where the antenna emits radiation Step, propagation time detected in propagation time detection step, Orientation set in step, and on the basis of the refractive index spatial distribution stored in the storage step, and has a target position location step of locating the position of the target.

  Further, the position locating device according to the present invention includes a controller that sets a transmission trigger signal, a directivity direction and a transmission time for a transmission wave, a transmitter that generates a transmission wave according to the transmission trigger signal set by the controller, and a control An antenna that radiates a transmission wave generated by a transmitter to space and receives a reflected wave from a target as a reception signal, and a reception time of the reception signal by the antenna and a controller A receiver that detects the propagation time of radio waves traveling back and forth between the antenna and the target from the set transmission time, a storage device that stores the refractive index spatial distribution of the atmosphere in the space that is radiated by the antenna, and reception The target position is determined based on the propagation time detected by the machine, the pointing direction set by the controller, and the refractive index spatial distribution stored in the storage device. It is obtained by a target position location device.

  According to this invention, since it comprised as mentioned above, a target position can be located at high speed and with high precision.

It is a block diagram which shows the structural example of the position location apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the position location apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating the operation principle of the position location apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the result of approximating the refractive index space distribution of a standard atmospheric model. It is a block diagram which shows the structural example of the position location apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structural example of the position location apparatus which concerns on Embodiment 3 of this invention. It is a flowchart which shows operation | movement of the position location apparatus which concerns on Embodiment 3 of this invention. It is a figure explaining an example (dichotomy) of the calculation of the directivity direction by the antenna directivity direction calculator in Embodiment 3 of this invention. It is a flowchart which shows an example (dichotomy) of the calculation of the directivity direction by the antenna directivity direction calculator in Embodiment 3 of this invention. It is a figure which shows the refractive index space distribution of a standard atmospheric model.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a block diagram showing a configuration example of a position locating device according to Embodiment 1 of the present invention.
As shown in FIG. 1, the position locator includes a controller 1, a transmitter 2, a transmission / reception switch 3, an antenna 4, a receiver 5, a storage device 6, and a target position locator 7. Here, the controller 1, the transmitter 2, the transmission / reception switch 3, the antenna 4, and the receiver 5 propagate in the direction of the antenna 4 (radiation angle of radio waves) and the propagation of radio waves between the antenna 4 and the target. A basic radar unit that transmits time to the target position locator 7 is configured.

  The controller 1 sets a transmission trigger signal, a directivity direction, and a transmission time for a transmission wave. The controller 1 is executed by program processing using a CPU based on software. The transmission trigger signal set by the controller 1 is transmitted to the transmitter 2, the data indicating the directivity direction is transmitted to the antenna 4 and the target position locator 7, and the data indicating the transmission time is transmitted to the receiver 5. .

  The transmitter 2 generates a transmission wave according to the transmission trigger signal from the controller 1. The transmission wave generated by the transmitter 2 is transmitted to the antenna 4 via the transmission / reception switch 3.

  The transmission / reception switch 3 switches the output destination according to the input source of the signal. Here, when a transmission wave is input from the transmitter 2, the transmission / reception switch 3 outputs the transmission wave to the antenna 4. In addition, when a reception signal is input from the antenna 4, the transmission / reception switch 3 outputs the reception signal to the receiver 5.

  The antenna 4 radiates a transmission wave from the transmitter 2 to the space in the directivity direction set by the controller 1 and receives a reflected wave from the target as a reception signal. A reception signal received by the antenna 4 is transmitted to the receiver 5 via the transmission / reception switch 3.

  The receiver 5 detects a propagation time in which a radio wave reciprocates between the antenna 4 and the target from the reception time of the received signal by the antenna 4 and the transmission time set by the controller 1. Data indicating the propagation time detected by the receiver 5 is transmitted to the target position locator 7.

  The storage device 6 stores the refractive index spatial distribution of the atmosphere in the space where the antenna 4 emits radiation. The storage device 6 is configured by an HDD, a DVD, a memory, and the like. The storage device 6 may store specifications of a function that approximates the refractive index spatial distribution. Here, examples of the function include a function that approximates a change in the square of the refractive index of the atmosphere in the radial direction of the earth or a function that approximates a change in the refractive index of the atmosphere in the radial direction of the earth. Data indicating the refractive index spatial distribution stored in the storage device 6 or the specifications of a function approximating the distribution is transmitted to the target position locator 7.

  The target position locator 7 determines the target position based on the propagation time detected by the receiver 5, the pointing direction set by the controller 1, and the data from the storage device 6. The target position locator 7 is executed by a program process using a CPU based on software.

  Next, the operation of the position locating apparatus configured as described above will be described with reference to FIG. Note that the storage device 6 stores the refractive index spatial distribution of the atmosphere in the space radiated by the antenna 4 or specifications of a function approximating the distribution (storage step). Data indicating the refractive index spatial distribution stored in the storage device 6 or the specifications of a function approximating the distribution is transmitted to the target position locator 7.

  In the operation of the position locator, as shown in FIG. 2, first, the controller 1 sets a transmission trigger signal, a directivity direction, and a transmission time for a transmission wave (step ST201, setting step). The transmission trigger signal set by the controller 1 is transmitted to the transmitter 2, the data indicating the directivity direction is transmitted to the antenna 4 and the target position locator 7, and the data indicating the transmission time is transmitted to the receiver 5. .

  Next, the transmitter 2 generates a transmission wave according to the transmission trigger signal from the controller 1 (step ST202, transmission wave generation step). The transmission wave generated by the transmitter 2 is transmitted to the antenna 4 via the transmission / reception switch 3.

  Next, the antenna 4 radiates the transmission wave from the transmitter 2 to the space in the directivity direction set by the controller 1, and receives the reflected wave from the target as a reception signal (step ST203, transmission / reception step). . A reception signal received by the antenna 4 is transmitted to the receiver 5 via the transmission / reception switch 3.

  Next, the receiver 5 detects the propagation time for the radio wave to reciprocate between the antenna 4 and the target from the reception time of the received signal by the antenna 4 and the transmission time set by the controller 1 (step ST204, propagation). Time detection step). Data indicating the propagation time detected by the receiver 5 is transmitted to the target position locator 7.

  Next, the target position locator 7 locates the target position based on the propagation time detected by the receiver 5, the pointing direction set by the controller 1, and the data from the storage device 6 (step ST205, Target location step).

Next, the operation principle of the position locating device of the present invention will be described with reference to FIG.
Here, the earth is a true sphere, and the distance from the center of the earth is r. Further, the refractive index is n, and when r <r _N , the refractive index depends on r, and when r> r _N , the refractive index is 1 independent of r. It is assumed that the radio wave is radiated at an elevation angle β = β ₀ from a position at a distance r = r ₀ from the earth center.

The distance D _t (ground range, great circle distance) measured along the ground surface from the radiation position (the position of the antenna 4) to the target position is strictly given by the following equation (3).

Further, the propagation optical path length P _t ′ from the antenna 4 to the target is strictly given by the following equation (4).

  If the ground range and the propagation optical path length are obtained, the target position can be obtained in consideration of the propagation time of the radio wave and the radiation angle of the radio wave (directivity direction of the antenna 4).

ここで、ｃ₁，ｃ₂，ｃ₃は定数であり、最小２乗法等により近似誤差が最小となるように定められる。 Here, the integrals of the equations (3) and (4) are obtained if the denominator root sign is a power series of the second order or less with respect to r, ie, the term of {n (r)} ² can be approximated by the following equation (5). This eliminates the need to evaluate the integral numerically, and enables the ground range and propagation optical path length to be obtained analytically, that is, at high speed.

Here, c ₁ , c ₂ , and c ₃ are constants, and are determined by the least square method or the like so that the approximation error is minimized.

ここで、ａ₁，ａ₂，ａ₃は定数であり、最小２乗法等により近似誤差が最小となるように定められる。 There are two possible methods of approximating the spatial distribution of the refractive index squared with the function form of Equation (5). One is a method of directly approximating the spatial distribution of the square of the refractive index as shown in Equation (5). Another method is a method of approximating the refractive index N as shown in the following equation (6).

Here, a ₁ , a ₂ , and a ₃ are constants and are determined by the least square method or the like so that the approximation error is minimized.

  As described above, the standard atmospheric refractive index space profile is given by an exponential function and has the characteristics shown in FIG. Therefore, regardless of which of the two methods is used, it is difficult to accurately approximate the whole up to an altitude of about 50 km with Equation (5) or Equation (6). In order to increase the approximation accuracy, the atmosphere is divided into a plurality of layers such as altitudes of 0 to 10 km, 10 to 20 km,..., And approximation by equation (5) or equation (6) is performed in each layer. Good. However, increasing the number of layer divisions increases the amount of computation, which is inconvenient for applications such as target real-time tracking. Therefore, the number of layer divisions needs to be determined appropriately in consideration of the required target positioning accuracy and allowable positioning time. In order to obtain a high approximation accuracy with a small number of divisions, it is effective to use an optimization method such as a genetic algorithm (GA) or Particle Swarm Optimization (PSO).

  FIG. 4 is a diagram showing a result obtained by approximating the refractive index space distribution (FIG. 10) of the summer atmosphere in the mid-latitude region shown in Non-Patent Document 2 with Expression (6). In this calculation, the altitude is divided into 6 layers of 0 to 5 km, 5 to 10 km, 10 to 20 km, 20 to 30 km, 30 to 40 km, and 40 to 50 km. It can be seen from FIG. 4 that the distribution shown in FIG. 10 can be approximated with high accuracy using equation (6).

  As described above, according to the first embodiment, the radiation angle of the radio wave (the direction of the antenna 4), the propagation time of the radio wave between the antenna 4 and the target, the refractive index space distribution of the atmosphere, Since the position of the target is determined using the method, the refractive index spatial distribution of the atmosphere can be considered more accurately than the conventional method, and the target position can be determined at high speed and with high accuracy.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing a configuration example of a position locating device according to Embodiment 2 of the present invention. In the position locating device according to the second embodiment shown in FIG. 5, the storage device 6 is deleted from the position locating device according to the first embodiment shown in FIG. 1, and a refractive index distribution calculator 8 and a refractive index distribution approximate function calculation are obtained. A device 9 is added. Other configurations are the same, and only the different parts are described with the same reference numerals.

  The refractive index distribution calculator 8 calculates the refractive index spatial distribution of the atmosphere in the space radiated by the antenna 4 based on meteorological data (temperature, pressure, humidity altitude distribution data) obtained by high-rise meteorological observation. It is. Data indicating the refractive index spatial distribution calculated by the refractive index distribution calculator 8 is transmitted to the refractive index distribution approximate function calculator 9 or directly to the target position locator 7.

The refractive index distribution approximation function calculator 9 approximates the refractive index spatial distribution calculated by the refractive index distribution calculator 8 with a function. At this time, the optimum number of layers and layer thickness are set, and the coefficient of the approximate function in each layer is obtained. Here, examples of the function include a function that approximates a change in the square of the refractive index of the atmosphere in the radial direction of the earth or a function that approximates a change in the refractive index of the atmosphere in the radial direction of the earth. Data indicating the specifications of the function used in the approximation by the refractive index distribution approximate function calculator 9 is transmitted to the target position locator 7.
The refractive index distribution calculator 8 and the refractive index distribution approximate function calculator 9 are executed by a program process using a CPU based on software.

  The target position locator 7 has a propagation time detected by the receiver 5, a pointing direction set by the controller 1, and a refractive index spatial distribution or refractive index distribution approximation function calculated by the refractive index distribution calculator 8. Based on the specifications of the function used in the approximation by the calculator 9, the target position is determined.

  In the first embodiment, the existing atmospheric refractive index space distribution is used. However, the refractive index spatial distribution of the atmosphere is sensitive to observation conditions such as observation region, observation season, observation time zone, etc., and it is not always optimal to use existing statistical data.

  The Japan Meteorological Agency regularly conducts high-rise weather observations using radiosondes at 16 weather stations and marine weather observation vessels nationwide. By creating an atmospheric refractive index spatial distribution model based on altitude distribution data of air temperature, atmospheric pressure, and humidity obtained from high-rise meteorological observations using radiosondes, the optimal model for each observation condition can be updated in near real time. It is thought that it is effective for improving the positioning accuracy.

  The following two methods can be considered as methods for creating a spatial refractive index spatial distribution model from temperature, atmospheric pressure, and humidity altitude distribution data obtained by upper meteorological observation. One is a method of directly approximating the measured raw data itself using the equation (5) or the equation (6). The other is a method of correcting the approximate function data stored in the storage device 6 of the first embodiment so that the error from the measured raw data is minimized.

  As described above, according to the second embodiment, instead of the existing atmospheric refractive index spatial distribution, an atmospheric refractive index spatial distribution model is created using meteorological data obtained by high-rise meteorological observation. Since it comprised, compared with Embodiment 1, the target position location accuracy improves more.

Embodiment 3 FIG.
In the first and second embodiments, the controller 1 sets the directivity direction of the antenna 4 and determines the target position. However, this method cannot observe a desired observation position. In an actual application, for example, it is often the case that a desired observation position is set for a specific artificial satellite or the like whose orbit is known, and a pointing direction for observing the position is set. Therefore, Embodiment 3 shows a configuration for solving the above.
FIG. 6 is a block diagram showing a configuration example of a position locating device according to Embodiment 3 of the present invention. The position locating device according to the third embodiment shown in FIG. 6 is obtained by adding an antenna pointing direction calculator 10 to the position locating device according to the first embodiment shown in FIG. Other configurations are the same, and only the different parts are described with the same reference numerals.

The storage device 6 transmits data indicating the stored refractive index spatial distribution or data of the function approximating the distribution to the target position locator 7 and the antenna directivity direction calculator 10.
The antenna directivity direction calculator 10 calculates the directivity direction of the antenna 4 based on the input observation position and data from the storage device 6. The antenna directivity direction calculator 10 is executed by a program process using a CPU based on software. Data indicating the directivity direction calculated by the antenna directivity direction calculator 10 is transmitted to the antenna 4 via the target position locator 7 and the controller 1.

The controller 1 does not set the directivity direction but sets only the transmission trigger signal and the transmission time for the transmission wave.
Further, the antenna 4 radiates a transmission wave from the transmitter 2 into the space toward the directivity direction calculated by the antenna directivity direction calculator 10 and receives a reflected wave from the target as a reception signal.
Further, the target position locator 7 determines the target position based on the propagation time detected by the receiver 5, the directivity direction calculated by the antenna directivity direction calculator 10, and the data from the storage device 6.

  Next, the operation of the position locating apparatus configured as described above will be described with reference to FIG. Note that the storage device 6 stores the refractive index spatial distribution of the atmosphere in the space radiated by the antenna 4 or specifications of a function approximating the distribution (storage step). Data indicating the refractive index spatial distribution stored in the storage device 6 or specifications of a function approximating the distribution is transmitted to the target position locator 7 and the antenna directing direction calculator 10.

In the operation of the position locator, as shown in FIG. 7, first, the antenna pointing direction calculator 10 receives the observation position (step ST701). This observation position is latitude, longitude, altitude, etc., and is input by the operator. For example, in an artificial satellite or the like whose orbit is known, it is possible to accurately know when and where it is located, and therefore an observation position for the artificial satellite can be set.
Next, the antenna directivity direction calculator 10 accepts data from the storage device 6 (step ST702).

Next, based on the observation position received in step ST701 and the data received from the storage device 6 in step ST702, the antenna directivity direction calculator 10 calculates the directivity direction of the antenna 4 for radiating radio waves to the observation position. (Step ST703). An iterative method is used in the calculation of the directivity direction. Details of this calculation process will be described later. Data indicating the directivity direction calculated by the antenna directivity direction calculator 10 is transmitted to the antenna 4 via the target position locator 7 and the controller 1.
Steps ST701 to ST703 correspond to the antenna directing direction calculation step of the present invention.

  Next, the controller 1 sets a transmission trigger signal and a transmission time for the transmission wave (step ST704, setting step). The transmission trigger signal set by the controller 1 is transmitted to the transmitter 2, and data indicating the transmission time is transmitted to the receiver 5.

  Next, the transmitter 2 generates a transmission wave according to the transmission trigger signal from the controller 1 (step ST705, transmission wave generation step). The transmission wave generated by the transmitter 2 is transmitted to the antenna 4 via the transmission / reception switch 3.

  Next, the antenna 4 radiates the transmission wave from the transmitter 2 to the space toward the directivity direction calculated by the antenna directivity direction calculator 10, and receives the reflected wave from the target as a reception signal (step ST706, ST706). Send / receive step). A reception signal received by the antenna 4 is transmitted to the receiver 5 via the transmission / reception switch 3.

  Next, the receiver 5 detects the propagation time for the radio wave to reciprocate between the antenna 4 and the target from the reception time of the received signal by the antenna 4 and the transmission time set by the controller 1 (step ST707, propagation). Time detection step). Data indicating the propagation time detected by the receiver 5 is transmitted to the target position locator 7.

  Next, the target position locator 7 locates the target position based on the propagation time detected by the receiver 5, the directivity direction calculated by the antenna directivity direction calculator 10, and the data from the storage device 6 ( Step ST708, target position locating step). Thereby, a desired target can be observed by directing the antenna 4 in the calculated directivity direction.

Next, the calculation process of the directivity direction of the antenna 4 in step ST703 will be described with reference to FIGS. In the following description, the case of using the bisection method as an iterative method will be described as an example.
In FIG. 8, the inner circular arc is the ground surface, and the outer circular arc is the contour line of the height H of the observation position. Also, let P be the point on the contour line of altitude H. In addition, an angle formed by a straight line connecting the antenna 4 and the point P (broken line in FIG. 8) and a ground tangent at the position of the antenna 4 (dashed line in FIG. 8) is ELa. Further, the propagation path of the radio wave from the antenna 4 to the point P is indicated by a thin solid line, and the radiation angle of the radio wave from the antenna 4 is ELs.

  In the directivity calculation processing by the antenna directivity calculator 10, first, as shown in FIG. 9, i is set to 0, and initial values of ELs (i) and ELs (i + 1) are set (step ST901). Next, ELa (i) and ELa (i + 1) are calculated by the equation (3) and geometry (step ST902). Here, since the observation direction ELt is set and known by the operator, the values of ELs (i) and ELs (i + 1) have an observation direction ELt between them, and ELs (i) and ELs (i + 1). ) And the observation direction ELt may be set to be relatively large. For example, if the observation direction ELt is 45 degrees, ELs (i) may be set to 60 degrees, for example, and ELs (i + 1) may be set to 30 degrees, for example. At this time, for example, from the data described in the ITU-R recommendation, etc., it is known to some extent how much the propagation path is curved by the refractive index distribution in the atmosphere. Good. With this setting, the observation direction ELt always exists between ELa (i) and ELa (i + 1).

Next, ELa ′, which is the midpoint between ELa (i) and ELa (i + 1), and ELs ′, which is the midpoint between ELs (i) and ELs (i + 1), are calculated (step ST903).
Next, it is determined whether ELa ′ is smaller than ELt (step ST904).

If it is determined in step ST904 that ELa ′ is smaller than ELt, ELa (i + 1) is replaced with ELa ′, and ELs (i + 1) is replaced with ELs ′ (step ST905).
On the other hand, if it is determined in step ST904 that ELa ′ is equal to or greater than ELt, ELa (i) is replaced with ELa ′, and ELs (i) is replaced with ELs ′ (step ST906).

Next, it is determined whether the absolute value ΔEL of the difference between ELt and ELa (i) is smaller than a minute amount ε (step ST907, convergence determination step).
If it is determined in step ST907 that ΔEL is equal to or greater than ε, i is incremented, the sequence returns to step ST903, and the above operation is repeated.
On the other hand, if it is determined in step ST907 that ΔEL is smaller than ε, the sequence ends. The arithmetic average value of ELs (i) and ELs (i + 1) obtained by this processing is the directivity direction of the antenna 4 for radiating radio waves to a desired observation position.

  In addition, although the example which used the bisection method as the iterative method was shown above, it is not restricted to this, You may use the Newton method, the Halley method, the Brent method, the Decker method, etc. as an iterative method.

  As described above, according to the third embodiment, the antenna pointing direction calculator 10 that calculates the pointing direction based on the input observation position and the refractive index spatial distribution of the atmosphere is provided. 2, the desired target can be observed by directing the antenna 4 in the calculated directivity direction.

  In the above description, the antenna directivity direction calculator 10 is provided for the configuration of the first embodiment. However, the antenna directivity direction calculator 10 may be provided for the configuration of the second embodiment. In this case, the antenna directivity direction calculator 10 calculates the function of the input observation position and the atmospheric refractive index spatial distribution calculated by the refractive index distribution calculator 8 or the approximation used by the refractive index distribution approximate function calculator 9. The directivity direction is calculated based on the specifications.

  Further, within the scope of the present invention, the invention of the present application can be freely combined with each embodiment, modified with any component in each embodiment, or omitted with any component in each embodiment. .

  DESCRIPTION OF SYMBOLS 1 Controller 2 Transmitter 3 Transmission / reception switch 4 Antenna 5 Receiver 6 Storage device 7 Target position locator 8 Refractive index distribution calculator 9 Refractive index distribution approximate function calculator 10 Antenna pointing direction Calculator.

Claims (14)

A setting step for setting a transmission trigger signal, a directivity direction and a transmission time for the transmission wave;
A transmission wave generation step of generating the transmission wave according to the transmission trigger signal set in the setting step;
A transmission / reception step of radiating the transmission wave generated in the transmission wave generation step to space and receiving a reflected wave from the target as a reception signal toward the directivity direction set in the setting step by an antenna;
A propagation time detecting step of detecting a propagation time of a radio wave reciprocating between the antenna and the target from the reception time of the received signal in the transmission / reception step and the transmission time set in the setting step;
A storage step of storing a refractive index spatial distribution of the atmosphere in a space radiated by the antenna;
A target position locating step for locating the target position based on the propagation time detected in the propagation time detecting step, the directivity direction set in the setting step, and the refractive index spatial distribution stored in the storing step; Orientation method. A storage step for storing the refractive index spatial distribution of the atmosphere;
Based on the input observation position and the refractive index spatial distribution of the atmosphere stored in the storing step, an antenna pointing direction calculating step for calculating a pointing direction;
A setting step for setting a transmission trigger signal and a transmission time for the transmission wave;
A transmission wave generation step of generating the transmission wave according to the transmission trigger signal set in the setting step;
A transmission / reception step of radiating a transmission wave generated in the transmission wave generation step into space and receiving a reflected wave from a target as a reception signal toward the directivity direction calculated in the antenna directivity direction calculation step by an antenna;
A propagation time detecting step of detecting a propagation time of a radio wave reciprocating between the antenna and the target from the reception time of the received signal in the transmission / reception step and the transmission time set in the setting step;
A target position locating step for locating the target based on the propagation time detected in the propagation time detecting step, the pointing direction calculated in the antenna directing direction calculating step, and the refractive index spatial distribution stored in the storing step; A position location method. In the storing step, specifications of a function approximating the refractive index spatial distribution are stored,
The position locating method according to claim 1 or 2, wherein, in the target position locating step, the position of the target is determined using the specifications of the function stored in the storing step. 4. The position locating method according to claim 3, wherein in the storing step, specifications of a function approximating a change in the square of the refractive index of the atmosphere in the radial direction of the earth are stored. 4. The position locating method according to claim 3, wherein in the storing step, specifications of a function approximating a change in the refractive index of the atmosphere in the radial direction of the earth are stored. A setting step for setting a transmission trigger signal, a directivity direction and a transmission time for the transmission wave;
A transmission wave generation step of generating the transmission wave according to the transmission trigger signal set in the setting step;
A transmission / reception step of radiating the transmission wave generated in the transmission wave generation step to space and receiving a reflected wave from the target as a reception signal toward the directivity direction set in the setting step by an antenna;
A propagation time detecting step of detecting a propagation time of a radio wave reciprocating between the antenna and the target from the reception time of the received signal in the transmission / reception step and the transmission time set in the setting step;
A refractive index distribution calculating step for calculating a refractive index spatial distribution of the atmosphere in a space where radiation is performed by the antenna, based on weather data obtained by high-rise weather observation;
A target position locating step for locating the target based on the propagation time detected in the propagation time detecting step, the directivity direction set in the setting step, and the refractive index spatial distribution calculated in the refractive index distribution calculating step; A position location method. A refractive index distribution calculating step for calculating a refractive index spatial distribution of the atmosphere based on meteorological data obtained by the upper meteorological observation;
Based on the input observation position and the refractive index spatial distribution of the atmosphere calculated in the refractive index distribution calculating step, the antenna directing direction calculating step for calculating the directing direction;
A setting step for setting a transmission trigger signal and a transmission time for the transmission wave;
A transmission wave generation step of generating the transmission wave according to the transmission trigger signal set in the setting step;
A transmission / reception step of radiating a transmission wave generated in the transmission wave generation step into space and receiving a reflected wave from a target as a reception signal toward the directivity direction calculated in the antenna directivity direction calculation step by an antenna;
A propagation time detecting step of detecting a propagation time of a radio wave reciprocating between the antenna and the target from the reception time of the received signal in the transmission / reception step and the transmission time set in the setting step;
A target position for locating the target based on the propagation time detected in the propagation time detection step, the directivity direction calculated in the antenna directivity direction calculation step, and the refractive index spatial distribution calculated in the refractive index distribution calculation step A location method having an orientation step. A refractive index distribution approximation function calculating step for approximating the refractive index spatial distribution calculated in the refractive index distribution calculating step with a function;
The position of the target is determined using the specifications of the function used in the approximation in the refractive index distribution approximate function calculating step in the target position determining step. Positioning method. The position locating method according to claim 8, wherein, in the refractive index distribution approximation function calculating step, a change in the square of the refractive index of the atmosphere in the radial direction of the earth is approximated. The position locating method according to claim 8, wherein, in the refractive index distribution approximation function calculating step, a change in the refractive index of the atmosphere in the radial direction of the earth is approximated. A controller for setting a transmission trigger signal, a directivity direction and a transmission time for a transmission wave;
A transmitter for generating the transmission wave according to a transmission trigger signal set by the controller;
An antenna that radiates a transmission wave generated by the transmitter toward space and receives a reflected wave from a target as a reception signal toward a directivity direction set by the controller;
A receiver for detecting a propagation time in which a radio wave reciprocates between the antenna and the target from a reception time of a reception signal by the antenna and a transmission time set by the controller;
A storage device for storing a refractive index spatial distribution of the atmosphere in a space radiated by the antenna;
A target position locator for locating the target based on a propagation time detected by the receiver, a directivity direction set by the controller, and a refractive index spatial distribution stored in the storage device. Positioning device. A storage device for storing the refractive index spatial distribution of the atmosphere;
An antenna pointing direction calculator for calculating a pointing direction based on the input observation position and the refractive index spatial distribution of the atmosphere stored in the storage device;
A controller for setting a transmission trigger signal and a transmission time for a transmission wave;
A transmitter for generating the transmission wave according to a transmission trigger signal set by the controller;
An antenna that radiates a transmission wave generated by the transmitter to space and receives a reflected wave from a target as a reception signal, in a directivity direction calculated by the antenna directivity direction calculator,
A receiver for detecting a propagation time in which a radio wave reciprocates between the antenna and the target from a reception time of a reception signal by the antenna and a transmission time set by the controller;
A target position locator for locating the target based on the propagation time detected by the receiver, the directivity direction calculated by the antenna directivity direction calculator, and the refractive index spatial distribution stored in the storage device A position locator equipped with and. A controller for setting a transmission trigger signal, a directivity direction and a transmission time for a transmission wave;
A transmitter for generating the transmission wave according to a transmission trigger signal set by the controller;
An antenna that radiates a transmission wave generated by the transmitter toward space and receives a reflected wave from a target as a reception signal toward a directivity direction set by the controller;
A receiver for detecting a propagation time in which a radio wave reciprocates between the antenna and the target from a reception time of a reception signal by the antenna and a transmission time set by the controller;
A refractive index distribution calculator that calculates the refractive index spatial distribution of the atmosphere in the space where radiation is radiated by the antenna, based on weather data obtained by high-rise weather observation;
A target position locator for locating the target based on a propagation time detected by the receiver, a directivity direction set by the controller, and a refractive index spatial distribution calculated by the refractive index distribution calculator. A position locator equipped with and. A refractive index distribution calculator for calculating the refractive index spatial distribution of the atmosphere based on the meteorological data obtained by the upper meteorological observation;
An antenna pointing direction calculator that calculates a pointing direction based on the input observation position and the refractive index spatial distribution of the atmosphere calculated by the refractive index distribution calculator;
A controller for setting a transmission trigger signal and a transmission time for a transmission wave;
A transmitter for generating the transmission wave according to a transmission trigger signal set by the controller;
An antenna that radiates a transmission wave generated by the transmitter to space and receives a reflected wave from a target as a reception signal, in a directivity direction calculated by the antenna directivity direction calculator,
A receiver for detecting a propagation time in which a radio wave reciprocates between the antenna and the target from a reception time of a reception signal by the antenna and a transmission time set by the controller;
A target for locating the target based on a propagation time detected by the receiver, a directivity direction calculated by the antenna directivity direction calculator, and a refractive index spatial distribution calculated by the refractive index distribution calculator A position locator equipped with a position locator.

Images