JPH0534447A - Multistatic radar method - Google Patents

Abstract

PURPOSE:To provide a multistatic radar method whereby the position of a target can be measured with high accuracy by utilizing angle information about azimuth and angles of elevation without electromagtnetic wave transmission time decided according to the positional relationship among a sending station, the target and a receiving station. CONSTITUTION:Three(or two) sending stations 5 are disposed in different positions and electromagnetic waves modulated so that they are mutually irrelevant are radiated toward a target 4. The waves reflected at the target are received at a receiving station 6 and the position coordinate of the target is calculated according to the time taken for the electromagnetic waves to be transmitted from the sending station to the receiving station and the position coordinates of the sending and receiving stations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement in the accuracy of position measurement of a target in a multistatic radar system.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a conventional multi-static radar system disclosed in, for example, Japanese Unexamined Patent Publication No. 1-217285, and FIG. 8 is a diagram showing an arrangement of transceiver stations during its operation. In the figure, 1 is a transmitting station provided with a transmitter 11, a transmitting antenna 12, and a timing device 13, 2 is a receiving antenna 21, a receiver 22, an azimuth / elevation angle calculator 23,
The receiving station 3 provided with the
A target position display device 1 including a position display device 32 and a target position display device 4 are targets.

The operation of the multi-static radar system configured as described above will be described with reference to the drawings. The electric wave transmitted from the transmitter 11 of the transmitting station 1 through the transmitting antenna 12 is reflected by the target 4, received by the receiving antennas 21 of the two receiving stations 2 arranged at different positions, amplified and detected by the receiver 22. After that, the azimuth and elevation calculator 23 calculates the target azimuth and elevation.

During this time, the synchronization between the transmitting station and the receiving station is achieved by the timing devices 13 mounted on the transmitting station 1 and the receiving station 2, respectively.
Kept by 24. Since the positions of the two receiving stations 2 are known or measurable, the distance Δr between them is easily obtained, and the position calculator 31 performs triangulation with the above two azimuth angles and elevation angles to obtain the target. The position is calculated and displayed on the position display 32. In this case, the measurement system of azimuth and elevation, that coincides with the beam width O _B, beam width O _B is given by O _B = lambda / D using the antenna aperture diameter D and the wavelength lambda, present at a distance R The target position measurement error ε is ε =
It is given by RO _B = λR / D. Now, set the wavelength λ to 0.03
If a target position at a distance of 100 km is measured using an antenna with m and an aperture diameter of 1 m, the measurement error is 3 km.

[0005]

In the conventional multi-static radar system, since the target position is calculated by using the azimuth angle and the elevation angle as described above, the measurement error of the target position increases in proportion to the distance. In addition, since the angle resolution function is limited by the antenna aperture diameter, there is a problem that a huge antenna is required to reduce the angle measurement error.

The present invention has been made to solve the above-mentioned problems, and radio wave propagation determined by the positional relationship between the transmitting station and the target and receiving stations without using the azimuth and elevation angle information. It is an object of the present invention to provide a multi-static radar system that can measure a target position with high accuracy by using time.

[0007]

The multistatic radar system according to the first aspect of the present invention is arranged at different positions, and the radio waves modulated so as to be uncorrelated with each other are shifted to different transmission timings with respect to the same target. Are separated by a single demodulator that synchronizes with the transmission timing of each transmitting station and that receives the radio waves reflected from the target, and a demodulator that separates the received radio waves by each transmitting station. A target position calculating means for calculating a target position coordinate using the radio wave propagation time of each radio wave, the position coordinate of each transmitting station, the position coordinate of the receiving station, and the speed of light is provided.

Further, the multistatic radar system according to the second aspect of the present invention includes a transmitting station that radiates radio waves to a target and a plurality of radio stations that are arranged to receive radio waves reflected from the target at different positions. It is provided with a receiving station and a target position calculating means for receiving the radio wave propagation time, the position coordinate of the receiving station, the position coordinate of the transmitting station and the speed of light obtained by each receiving station by a predetermined communication means and calculating the position coordinate of the target. is there.

[0009]

In the receiving station according to the first aspect of the present invention, the radio waves radiated and reflected by the same target from a plurality of transmission stations are separated for each transmission station, and the radio wave propagation time of each radio wave and the position of each transmission station are separated. The target position coordinates are obtained by solving a multi-dimensional simultaneous equation using the coordinates, the position coordinates of the receiving station, and the speed of light C as known parameters.

According to the second aspect of the invention, the propagation time of the radio wave obtained by receiving the radio waves radiated and reflected by the target from a single transmitting station at a plurality of receiving stations having different receiving positions, respectively. , Position coordinates of own station, position coordinates of transmitting station, speed of light C
Each received signal of is transmitted to the target position calculation means through a predetermined communication means, and the calculation means uses the position coordinates of the transmitting station and the receiving station, each propagation time, and the speed of light transmitted from each receiving station as parameters. The target position coordinates are obtained by solving the simultaneous equations.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 5 is a transmitting station, 6 is a receiving station, and 4 is a target. 2 and 3 are diagrams showing the configurations of the transmitting station 5 and the receiving station 6, respectively. In FIG. 2, 51 is a transmitting antenna, 52 is an amplifier, 53 is a reference signal generator, and 54 is a reference signal generator.
Is a modulator, 55 is a carrier generator, and 56 is a timing device. In FIG. 3, 61 is a receiving antenna, 62 is an amplifier, 63 is a phase detector, 64 is a reference signal generator, 65 is a demodulator, 66 is a time measuring device, 67 is a target position calculating device, 6
Reference numeral 8 is a display.

The operation of the multistatic radar system of the present invention configured as described above will be described with reference to the drawings. In the three transmitting stations 5 arranged at different positions, the high frequency signal (carrier) generated in the carrier generator 55 is generated in the reference signal generator 53 in the modulator 54 so as to be uncorrelated with each other between the different transmitting stations. It is modulated by the generated reference signal, amplified by the amplifier 52, and radiated from the transmission antenna 51 to the target 4.

Radio waves (modulated high frequency signals) radiated from the three transmitting stations 5 are reflected by the target 4 and received by the receiving antenna 61 of the receiving station 6. At this time, the radio wave transmitted from each transmitting station 5 is the distance from the transmitting station 5 to the target 4 and
Since the distance propagates from the target 4 to the receiving station 6, a delay time corresponding to this distance is generated between the transmission time and the reception time.

Radio waves received by the receiving antenna 61 are amplified by an amplifier 62, detected by a phase detector 63, and then individually demodulated by a demodulator 65 into three types of demodulated signals corresponding to each transmitting station. It The three types of demodulated signals are generated by the reference signal generator 64. In the transmitting station 5 and the receiving station 6, the time measuring devices 56 and 66 incorporated therein, respectively.
By doing so, the time is adjusted and a synchronized reference signal is generated.

The demodulated signal separated for each transmitting station is input to the target position calculating device 67, and the times T ₁ , T ₂ , and T ₃ required for each propagation are measured. Furthermore, the position coordinates (x ₁ , y ₁ , z ₁ ) of the three transmitting stations 5 (x ₂ , y ₂ , z ₁ )
₂ ), (x ₃ , y ₃ , z ₃ ) and the position coordinates (x ₀ , y ₀ , z ₀ ) of the receiving station 6 and the speed of light C are known or measurable parameters. By solving the simultaneous three-way equation shown in Equation 1, the target position coordinates (x,
y, z) is calculated.

[0016]

[Equation 1]

The target is displayed on the display 68 using the calculated target position coordinates (x, y, z). At this time,
The measurement accuracy of the target position coordinates (x, y, z) depends on the measurement error of the delay time (transmission time) between transmission and reception, but this error has been achieved by the current radar as well, and is 10 ns to 100 ns. Can be reduced to about 3 m to 30 m, which is 1/1000 to 1 of the error 3 km of the conventional device.
/ 100 can be achieved. Further, when the observation target is limited to the target existing on the ground or the sea, the altitude z is known (z = 0 and the unknowns are two, x and y in the position coordinate of the target. Therefore, in this case, The number of transmitting stations is sufficient to be two, and the target position (x, y) can be calculated by solving the simultaneous binary equation shown in Expression 2.

[0018]

[Equation 2]

Example 2. 4, 5 and 6 are embodiments of the invention according to claim 2, FIG. 4 is a diagram showing a multi-static radar system according to the present invention, FIG. 5 is a diagram showing a configuration of a transmitting station, and FIG. It is a figure which shows the structure of a receiving station. In the figure,
Reference numeral 69 is a communication means for transmitting the position coordinates of the transmitting station and the receiving station obtained at each receiving station and the radio wave propagation time between transmission and reception to the target position calculating device 67, and the components of other symbols are respectively implemented. The same or equivalent device as in Example 1 is shown.

In this embodiment, the radio wave radiated from one transmitting station 5 toward the target 4 is reflected by the target and is received by a plurality of receiving stations 6. The operation of each receiving station 6 is the same as that of the first embodiment, but since the transmitting station 5 is single, the formula for determining the target position coordinates (x, y, z) is 1 of the formula 1. I can only ask for one.

Therefore, via the communication means 69, the position coordinates (x ₀ , y ₀ , z) of the transmitting station 5 which are the parameters of this equation.
₀ ), the position coordinates (x _i , y _i , z _i ) of the receiving station 6 and the radio wave propagation time T _i between transmission and reception are transmitted to the target position calculation device 67. Here, i is an arbitrary number of {1, 2.3}.

When the target position calculating device 67 obtains the above parameters from three different receiving stations 6, the target position calculating device 67 solves the formula 1 to obtain the position coordinates (x, y,
z) is calculated.

This means that the position coordinates (x ₃ , y
₃ , z ₃ ), a third transmitting station or receiving station is added, and delay times T ₁ , T ₂ , T ₃ between transmitting and receiving with respect to the three transmitting stations or receiving stations and position coordinates (x ₁ , y ₁ , z
₁ ), (x ₂ , y ₂ , z ₂ ), (x ₃ , y ₃ , z ₃ ) and the position coordinates (x ₀ , y ₀ , z ₀ ) of the receiving station or the transmitting station and the speed of light C, The position coordinates (x, y, z) in the three-dimensional space of the target existing on the ground, on the sea surface, or in the air are calculated. Further, when the above parameters can be obtained only from two different receiving stations 6, the equation (2) is solved to obtain the position coordinate (x, y) of the target on the ground or the sea surface.

At this time, the target position calculating device 67 and the display 68 can be installed at any place as long as they can communicate with each receiving station 6, and can also be built in each receiving station.
As the communication means 69, wireless and arbitrary means can be used, and use of a telephone line as a wired communication means is also conceivable.

[0025]

As described above, according to the first aspect of the invention, the position coordinates of the target can be calculated from the propagation times of the radio waves transmitted from the plurality of transmitting stations.
The measurement accuracy can be improved as compared with the method using the elevation angle.

According to the second aspect of the invention, even in one transmitting station, by combining the propagation times of the radio waves received by the plurality of receiving stations, the target position can be obtained in the same manner as in claim 1. The coordinates can be obtained with high accuracy.

[Brief description of drawings]

FIG. 1 is a layout diagram showing a layout of transmitting stations and receiving stations during operation of a multi-static radar according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a transmitting station according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a receiving station according to the first embodiment of the present invention.

FIG. 4 is a layout diagram showing a layout of transmitting stations and receiving stations during operation of the multi-static radar according to the second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a transmitting station according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram showing a configuration of a transmitting station according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing configurations of a transmitting station and a receiving station in a conventional multistatic radar system.

FIG. 8 is a layout diagram showing a layout of transceiver stations during operation of a conventional multi-static radar.

[Explanation of symbols]

4 goals 5 transmitter 6 Receiving station 61 demodulator 67 Target Position Calculation Device 69 Communication means

Claims (2)

[Claims] 1. A plurality of transmitting stations arranged at different positions and radiated to the same target by shifting transmission timings of radio waves modulated so as to be uncorrelated, and synchronized with the transmitting timing of each transmitting station. A single receiving station that receives the radio waves reflected from the target, a demodulator that separates the received radio waves for each transmitting station, the radio wave propagation time of each separated radio wave, the position coordinates of each transmitting station, and the receiving station. And a target position calculating means for calculating the position coordinate of the target using the position coordinate and the speed of light. 2. A transmitting station that radiates radio waves to a target,
Predetermine a plurality of receiving stations arranged to receive the radio waves reflected from the target at different positions, and the radio wave propagation time obtained at each receiving station, the position coordinates of the receiving station, the position coordinates of the transmitting station, and the speed of light. A multi-static radar system, comprising: a target position calculating means for calculating a position coordinate of a receiving target by a communication means.