JPH10206535A - Radar-screening region supporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grasp the direction of a ship even at a water region where no radar information such as island shade can be obtained by successively calculating the speed of a traveling target and a predicted position in a radar radio wave shielding region based on information of Doppler frequency and distance to the traveling target being measured by a plurality of transmission and reception means for Doppler measurement. SOLUTION: An object target tracking means 2 is widely adopted, for example, for preventing collision of ships and aircraft and inputs information of the image and position of each target from a radar device 1 and a trigger signal for tracking. A display device 3 inputs and displays the image and position information of a tracked target from the target-tracking means 2, and converts position information that is inputted from polar coordinates to rectangular coordinates via a coordinate conversion means as needed for raster display. Transmitters and receivers 5 and 6 for Doppler measurement discharge radio waves in UHF and VHF bands into air, and a target speed/position operation means 7 successively calculates the speed and the predicted position of the traveling target within a radar radio wave shielding region based on the information of the Doppler frequency and the distance to the traveling target being measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for supporting loss of radar information in a radar radio wave shielding area.

[0002]

2. Description of the Related Art Radar is radio detection and rangin.
An abbreviation of g, which emits radio waves from its own transmitter and receives the radio waves reflected back from the target with a receiver to detect the target, and its distance, direction, and moving speed. It is a wireless observation device that obtains information such as For example, radar is also used as a device that can monitor and monitor a moving target (such as a ship) at sea using radio waves from a land-based monitoring station in order to monitor marine traffic.
There is no practical device that can be used for this purpose.

A disadvantage of this radar is that a target cannot be detected in a shielding area of radar radio waves. FIG. 7 is a diagram illustrating a radar covered area and a radar shielded area.
In FIG. 7, the point O is a radar installation position, and it is assumed that a marine traffic monitoring radar installed at the point O monitors a moving target traveling in the bay. Also, there is one island in the bay, and the radar radio wave from point O does not reach this island shade, so the range of this island shade seen from point O is the radar shielding area. The time t ₀ , t ₁ , t ₂ ,
Positions at t ₃ and t ₄ are P ₀ , P ₁ , P ₂ , P
₃ and P ₄ , the position P ₀ and the position P ₀ Although P ₄ This target can be detected because it is radar covered region, position P ₁
Can not be detected this target for between P ₃ is a radar shield region from. That is, the radar is in a state where the target is lost.

[0004]

As described above, in a sea surveillance radar for a harbor or an archipelago, the target being monitored is located in a radar shielded area such as an island shade or a bridge or a building structure. When entering, there is a problem that the target is lost and the tracking of the target by the radar cannot be continued.
As a conventional countermeasure against this, in addition to the conventional radar (this is assumed to be # 1 radar), a new radar (this is referred to as # 1 radar)
2 radar), and the shielding area of # 1 radar is #
Position that will be the coverage area of 2 radar (for example, point Q in FIG. 7)
The problem was solved by installing it. However, installing two radars in one harbor has the economic problem of doubling the cost of a maritime surveillance system, and assigns different frequencies to the two radars to avoid interference between the two radar waves. Although it is necessary, there still remains a problem that it is not easy to obtain a desired radar frequency assignment.

[0005]

SUMMARY OF THE INVENTION A radar shielding area support apparatus according to the present invention is installed so as to have an antenna directivity including a shielding area for radar radio waves within its own coverage area from different positions, and each of them has a predetermined period. A radio wave of a predetermined frequency with a predetermined pulse width is transmitted by the antenna directivity characteristic every time,
Receives reflected radio waves from a moving target existing in its own coverage area, measures the Doppler frequency based on the moving speed of the moving target, and measures the distance from its own installation position to the moving target. Transmitting and receiving means for Doppler measurement,
A target velocity for sequentially calculating the velocity and the predicted position of the moving target within the radar wave shielding area based on information on the Doppler frequency and the distance to the moving target measured by the plurality of Doppler measurement transmitting / receiving units, respectively. And a position calculating means. As a result, when a conventional maritime surveillance radar system tracks a marine-going target, the target tracking operation is continued even in water areas where radar information cannot be obtained due to radar shielding areas such as island shade, and the movement of ships etc. Can be grasped.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of a radar shielding area support device according to Embodiments 1 and 2 of the present invention. In FIG. 1, reference numeral 1 denotes a radar device, which in this example is a radar for monitoring marine traffic. 2 is a target tracking means,
A video of each target, information on its position, and a trigger signal are input from the radar device 1 to track each target. The target tracking means 2 is a means widely used in, for example, a collision preventive device for a ship or an aircraft, and includes a track and speed of the target moving from the past to the present and a future (that is, the next An estimated position (when the antenna is rotated) is predicted and calculated by a Kalman filter or the like, and tracking is performed using a tracking gate. A display device 3 is a device (for example, a PPI display device) that inputs and displays the video and position information of the tracking target from the target tracking means 2. In some cases, the position information input to the display device 3 may be converted from polar coordinates to rectangular coordinates via coordinate conversion means (not shown) and displayed on a raster display device. A target tracking display device using a conventional radar is constituted by the above-described devices and means.

In FIG. 1, reference numerals 5 and 6 denote # 1 and # 2 Doppler measuring transceivers, respectively, and reference numeral 7 denotes a target speed / position calculating means. Is composed. FIG. 2 is a diagram showing an example of installation positions and directional characteristics of the # 1 and # 2 Doppler measurement transceivers of FIG. 1, and FIG. 3 is a diagram showing transmission and reception timings of the # 1 and # 2 Doppler measurement transceivers of FIG. FIG. 3A shows the first embodiment.
FIG. 3B shows the timing of the second embodiment. FIG. 4 is a diagram for explaining the target speed / position calculation method of FIG. 1, and FIG. 5 is a flowchart for explaining the operation of the radar occlusion area support apparatus of FIG.

In FIG. 2, a point O is an installation position of the radar device 1, and a marine traffic monitoring radar installed at the point O monitors a moving target traveling in the bay. There are two islands. Therefore, the illustrated radar shielding area exists in the shade of the island. The # 1 and # 2 Doppler measuring transceivers 5 and 6 have antenna directivity characteristics (for example, one point in FIG. 2) including a radar radio wave shielding area in their own coverage area from different positions (for example, points A and B in FIG. 2). (A chain line and a two-dot chain line).

# 1, # 2 Doppler measurement transceivers 5, 6
Both transmit pulse radio waves repeatedly at regular intervals and calculate the Doppler frequency and the distance to the target from the received signal from the moving target, but avoid mutual interference between the two transmitted and received radio waves The method for this is different between the first embodiment and the second embodiment. In the first embodiment, since the # 1 and # 2 Doppler measurement transceivers 5 and 6 have different transmission frequencies f ₁ and f ₂ , respectively, as shown in FIG. Time can be synchronized. In this case, for example, a transmission trigger signal may be input from the radar device 1 and transmission may be performed in synchronization with the trigger signal.

# 1, # 2 Doppler measurement transceivers 5, 6
Are, for example, U
Radio waves having specific frequencies of f ₁ and f ₂ in the HF or VHF band, a pulse width of t ₀ (for example, 1 to 10 μs), and a repetition period of T (for example, 1 to 10 ms) are emitted into the atmosphere (see FIG. 3). (See the transmission waves f ₁ and f ₂ in (a)). When the moving target exists in each of the covered areas, the received waves reflected from the moving target and subjected to the Doppler shift are received by the Doppler measuring transceivers 5 and 6 at # 1 and # 2, respectively (FIG. 3). (A) of the received wave f ₁ ± Δf ₁ and f ₂ ± Δf ₂ (see FIG. 2A). # 1, # 2 Doppler measurement transceivers 5, 6
Is an operation that is independent of radar, so in general, shortly before a moving target enters the radar shielding area,
The antenna directivity is set so that the reflected radio waves can be sufficiently received shortly after the radar shielded area (see the dashed-dotted line and the dashed-dotted line in FIG. 2).

When a wave signal having a frequency f (wavelength λ) is transmitted from a certain measurement point to a moving target, the reflected wave from the moving target having a relative velocity V _{r in the} direction to the measuring point is Doppler. Undergoes a shift and its Doppler frequency f
It is well known that _D is expressed by the following equation (1), where C is the propagation speed of the radio wave. However, the wavelength λ is λ = C / f. f _D = 2V _r · f / C = 2V _r / λ (1) Accordingly, by measuring the Doppler frequency (difference between the transmission frequency and the reception frequency), the relative velocity V _r can be obtained from the following equation (2). . V _r = C · f _D / 2f (2)

FIG. 4A shows the velocity vector V of the moving target at the point P and the relative velocity vectors V _rA and V _rB of the moving target with respect to the points A and B, respectively. Here, the relative speed vector V _rA with respect to the point A is a direction away from the point A, and the relative speed vector V _{rB with} respect to the point B.
Is a direction approaching the point _B , so that the scalar quantities V _rA , V _B are multiplied by unit vectors v _A , v _B which are positive when approaching and negative when _approaching .
_Can be converted to _rB . When V _rA is negative, the Doppler frequency f _DA is also negative, and when V _rB is positive, the Doppler frequency f _DB
Also has a positive relationship.

FIG. 4B shows a method of measuring the position of point P. By measuring the times t _A and t _B from the time when the pulsed radio wave is transmitted from the measurement points A and B to the time when the reflected radio wave is received from the moving target at the point P, respectively, the measurement points A and B are measured. distance R _AP to point P can be obtained _{R BP (R AP = t a} · C / 2, R BP = t B · C
/ 2, where C is the propagation speed of the radio wave). If the distance R _AB between the measurement points A and B is known, the position of the point P can be measured by the principle of triangulation.

# 1, # 2 Doppler measurement transceivers 5, 6
Is the Doppler frequency f _DA , f _DB and the moving target P every predetermined repetition period T (for example, the above 1 to 10 ms).
The distances R _AP and R _{BP up} to this point can be measured. However, in order to improve the measurement accuracy, it is desirable to average the measured values. Therefore, the target velocity / position calculating means 7 in FIG. 1 receives the measured values of f _DA , f _DB , R _AP , and R _BP measured by the # 1 and # 2 Doppler measuring transceivers 5 and 6, for example, The average value of each of the ten measured values is obtained, and the calculation is performed using the information obtained by the averaging process. In this case, even when the transmission repetition period T is 10 ms, averaging information is obtained every 10 T = 100 ms (0.1 seconds), and the position change of the moving target during this 0.1 second is obtained. , The effect of improving the measurement accuracy by the averaging process is greater. Accordingly, in the following description, data such as f _DA , f _DB , R _AP , R _BP and V, V _rA , V _rB , v _A , and v _{B obtained} therefrom will be described as data after averaging processing.

When the position P of the moving target is determined by radar or the measuring method shown in FIG. _4B , the values of V _rA and V _rB are _obtained from f _DA and f _DB by using the above equation (2). Ask for it,
Using the point P as a starting point of each velocity vector, FIG.
As shown in, the magnitude of the relative velocity vector V _rA an extension passing through the point P from the point A, also respectively plotting the magnitude of the relative velocity vector V _rB on a straight line extending from the point P to the point B. And the tip P _A of the relative velocity vector V _rA, and a leading end P _B of the relative velocity vector V _rB, the intersection of two straight lines ruled perpendicularly each plotting the point P such that the tip of the velocity vector V Thus, the velocity vector V can be obtained.

If the above schematic description is represented by a general function,
It looks like this: In this example, the coordinate origin of each point is the installation position O of the radar device 1. Now the measurement points A, B, the coordinate position of the moving target _{P (X A, Y A)} , (X
_B, Y _B), (X _P, as Y _P), when the velocity vector of the moving target that is V, the measurement point A, the relative velocity vector V _rA for B, V _rB the following function (3), (4 ) Expression. V _rA = F (X _A , Y _A , X _P , Y _P , V) (3) V _rB = F (X _B , Y _B , X _P , Y _P , V) (4)

Accordingly, the Doppler frequencies f _DA and f _{DB at the} measurement points A and B are given by the following functions (5) and (5), respectively, assuming that the unit vectors in the directions of the points A and B from the moving target are v _A and v _B , respectively. It is shown by equation (6). f _DA = f (X _A , Y _A , X _P , Y _P , V, v _A ) (5) f _DB = f (X _B , Y _B , X _P , Y _P , V, v _B ) ( 6) Here, the velocity vector V of the moving target is a component V in the X-axis direction.
_{Since x} and the component V _Y in the Y-axis direction are combined, the above equations (5) and (6) can be expressed as equations (7) and (8). f _DA = f _A (X _A , Y _A , X _P , Y _P , V _X , V _Y , v _A ) (7) f _DB = f _B (X _B , Y _B , X _P , Y _P , V _{X, V Y, v B)} ... (8)

The target tracking operation of FIG. 1 will be described with reference to the flowchart of FIG. The numerical value following S in the figure indicates a step number. First, the target tracking means 2 obtains information on the initial position (X _P0 , Y _P0 ) of the moving target from the radar device 1 before the moving target enters the radar shielding sea area (see S1 in FIG. 5). ). In this case, velocity information can also be obtained by target tracking by the radar, but this is about the reference value of the velocity vector obtained from the Doppler frequency.

Even before the moving target enters the radar shielding sea area, the # 1 and # 2 Doppler measuring transceivers 5 and 6 operate at the Doppler frequencies f _DA and f _DA of the moving target existing in their own coverage areas. _{The DB} is repeatedly measured, and the target speed / position calculating means 7 acquires an averaged processing value of the measured value (FIG. 5).
S2). Here, the positions of the measurement points A and B (X _A ,
Y _A ) and (X _B , Y _B ) are known, and the initial position P ₀ of the target is obtained from the radar device 1 via the target tracking means 2. The unit vectors v _A and v _{B of the} vector components are also determined, and the unknowns are only V _x and V _y for the target velocity / position calculation means 7.

Then, the target velocity / position calculating means 7 solves the simultaneous equations of the equations (7) and (8) to obtain the X-axis and Y-axis components V _X and V _Y of the velocity vector. (See S3 in FIG. 5). Next, the initial position (X _P0 ,
Y _P0 ) and the Doppler frequencies f _DA , observed at points A and B,
by using the velocity vector V calculated from f _DB, calculates the next (for example, after the 10T) first predicted position where the Doppler frequency is obtained (this position is X _P1, Y _P1) (Figure 5
S4)). That is, _assuming that the unit vectors of the velocity component vectors V _X and Y _Y in the X and Y axis directions at the initial position (X _P0 and Y _P0 ) are v _X and v _Y , respectively, the first predicted position (X _P1 , Y _P1 ) Can be calculated from the following equations (9) and (10). X _P1 = X _P0 + V _X · v _X · 10T (9) Y _P1 = Y _P0 + V _Y · v _Y · 10T (10)

If the first predicted position (X _P1 , Y _P1 ) is still within the radar coverage, the predicted position can be confirmed or corrected by the detection position obtained by the radar after 10T, and The velocity vectors V _X and V _Y obtained from the Doppler frequency can also be compared with radar information. When the same type of information can be obtained from both the radar and the Doppler measurement transceiver, the radar information is usually more accurate for the position information (since the azimuth and distance of the target can be directly detected by the radar, For speed information, the accuracy is better if obtained from the Doppler frequency. Therefore, it is desirable to use information with higher accuracy.

However, the first predicted position (X _P1 , Y _P1 )
There (see P ₁ in FIG. 7) in the case of radar shielding region, use of the predicted position as the start point of the next velocity vector. And the Doppler frequencies f _DA , f observed again after 10T
_{From the DA} , the target velocity / position calculating means 7 calculates the velocity vectors V _X , V _X starting from the first predicted position (X _P1 , Y _P2 ).
_Y is calculated again (see S5 in FIG. 5). Then, the next Doppler frequency is obtained again by the velocity vectors V _X and V _Y starting from the first predicted position (X _P1 , Y _P1 ).
The second predicted position (X _P2 , Y _P2 ) is calculated (S6 in FIG. 4).
See).

As described above, the target speed / position calculating means 7 starts from the radar detection position before the moving target enters the radar shielding area, and obtains the velocity information based on the Doppler frequency obtained at this start point. Next, an operation of predicting a first position at which a Doppler frequency is obtained, and then predicting a second position at which a Doppler frequency is further obtained based on velocity information based on the Doppler frequency obtained at the first predicted position. By repeating this, the speed and position information of the moving target in the radar shielding area is sequentially supplied to the target tracking means 2. The target tracking means 2 does not obtain radar information while the moving target is in the radar shielded area, and therefore continues the target tracking operation based on the information supplied from the target speed / position calculation means 7 instead. Then, the tracking position and the speed of the target are displayed on the display device 3 (see S7 in FIG. 5).

However, if the calculation of the predicted position is repeated after entering the radar shielded area, errors in each prediction are added up. In such a case, the target speed / position calculation means 7 sets The distance R ₁ from the position to the point A and the distance R ₂ from the predicted position to the point B are calculated, and when the next Doppler frequency is obtained, the distances are actually measured from the # 1 and # 2 Doppler measuring transceivers 5 and 6. Compared with the distances R _AP and R _BP from points A and B input as values to the moving target (see FIG. 4B), errors ε ₁ = R _AP −R ₁ and ε ₂ = R _BP when one of the absolute values of -R ₂ exceeds a predetermined threshold value, the measured value R
_The predicted position is corrected to the target position calculated based on _AP and _RBP (see S8 and S9 in FIG. 5).

While the moving target being tracked exists in the radar shielding area, that is, while the position information of the target cannot be obtained from the radar apparatus 1 via the target tracking means 2 (S10 in FIG. 5).
5), and the target speed / position calculation means 7 performs the processing in S5 to S5 in FIG.
The processing of S10 is repeatedly performed. When the moving target enters the radar coverage again and radar information can be obtained again, the target speed / position calculation means 7 delivers the final target position and speed information to the target tracking means 2. To end the operation. The target tracking means 2 updates the position information of the delivered target position and speed information to the position detected by the radar (since the radar position information has higher accuracy),
Based on these information, the target tracking in the radar coverage area is continuously performed, and the display of the tracked target on the display device 3 can be continuously performed.

In FIG. 1, the target tracking means 2 and the target speed / position calculation means 7 have been described as separate means. However, this means performs the conventional operation and performs the operation of the present invention. This is for the purpose of separately describing means and the present invention, and the present invention is not limited to this configuration. For example, the operations of the two units may be performed by one personal computer or the like.

According to the first embodiment as described above, by providing at least two Doppler measurement transceivers covering the radar shielding area such as an island shade, the conventional marine surveillance radar system and the like When a target is tracked, the target tracking operation can be continued even in a water area where radar information cannot be obtained, and it is possible to grasp a trend of a ship or the like, which greatly contributes to sea monitoring.

Embodiment 2 FIG. FIG. 3B is a diagram showing the transmission and reception timings of the # 1 and # 2 Doppler measurement transceivers according to the second embodiment of the present invention. In the second embodiment, in order to enable the two Doppler measurement transceivers 5 and 6 to transmit radio waves of the same frequency f, respectively, and to avoid mutual interference of radio waves, the transmission time of each fixed period T is alternately set to # 1 Doppler measurement. To the transceiver for transmission 5 and the transceiver for Doppler measurement # 2. Then, the transmission time is set to t ₁ , t ₂ , t ₃ , t ₄
..., the # 1 Doppler measurement transceiver 5 transmits only at the transmission times t ₁ , t ₃ , t _5, ..., And the # 2 Doppler measurement transceiver 6 transmits the transmission times t ₂ , t ₄ , t ₆ . Only to send to.

In the second embodiment, the transmission cycle of each of the Doppler measuring transceivers 5 and 6 is 2T (see FIG. 3B). For example, when 2T is 10 ms, two Doppler frequencies of 10 Is obtained every 0.1 second, and even if the moving speed is obtained every 0.1 second, the operation of the present invention is not affected at all. Since it is not easy to obtain the current assignment of the radio wave of the desired frequency, the effect that a plurality of transmitters can transmit the radio wave of the same frequency is great. If there are two or more Doppler measurement transceivers, for example, three units # 1, # 2, and # 3, the transmission time is set to #
, # 1, # 2, # 3, # 1, # 2, # 3,... May be sequentially assigned, and each transmitter may transmit only at the transmission time assigned to itself.

Embodiment 3 FIG. 6 is a diagram showing a configuration of a transponder for a Doppler signal according to Embodiment 3 of the present invention. In the third embodiment, the transmission outputs of the # 1 and # 2 Doppler measurement transceivers 5 and 6 in FIG. 1 are low power, the directional characteristics of the antenna are omnidirectional, and the target is small (therefore, the radio wave is small). The effective reflection area of the target is also small) and at a long distance, etc., a sufficient reflection signal cannot be directly obtained from the moving target within the coverage area, and as a result, the measure for the case where the Doppler frequency cannot be measured is shown. I have. In the third embodiment,
When the direct reflected power from the moving target received by the Doppler measurement transceiver installed at the observation point as described above is too small, a transponder is mounted on the moving object, and the transponder's transmission wave is received. It is intended to obtain the following reception power.

In FIG. 6, reference numeral 10 denotes a Doppler signal transponder mounted on a moving body,
1, a transmission antenna 12, an amplifier 15, a delay circuit 16, a transmitter 17, and a switch 18. 20
Is a Doppler measurement transceiver installed at the observation point. In this example, UHF or VHF transmits and receives radio waves of a specific frequency, and measures Doppler frequency from a mobile object.

The Doppler measuring transceiver 20 shown in FIG. 6 has a specific frequency f from a transmitting antenna (not shown) like the # 1 and # 2 Doppler measuring transceivers 5 and 6 in FIG.
Then, a radio wave having a pulse width of t ₀ and a repetition period of T is emitted into the atmosphere. In the Doppler signal transponder 10 mounted on a moving object, first, a receiving antenna (for example, a rod antenna or the like) 11 transmits the specific frequency f which has propagated in the atmosphere.
And receives only a radio wave in a frequency band having a bandwidth of Δf before and after the center frequency, and supplies the received signal to the amplifier 15 via the switch 18.

The switch 18 shown in FIG.
The circuit between the output terminal and the input terminal of the amplifier 15 is normally closed so that the radio wave transmitted from the transmission antenna 12 of the Doppler signal transponder 10 is not directly input to the amplifier 15 via its own reception antenna 11. When the reception signal from the reception antenna 11 is supplied to the amplifier 15, the signal is opened immediately, and is closed again after a certain time has elapsed.

The amplifier 15 is a linear amplifier, and has a proportional relationship with the amplitude between input and output signals. The proportional constant has a uniform value over a predetermined range even if the magnitude of the input signal changes or the frequency slightly changes. Therefore, the input signal is linearly amplified and output without distorting the waveform of the input signal or changing the frequency or phase. The amplified signal output from the amplifier 15 is supplied to the delay circuit 16.

The delay circuit 16 delays the input signal from the amplifier 15 by a predetermined time τ (τ is generally set to a value slightly larger than the pulse width t ₀ ), and transmits the delayed signal. To the vessel 17. In the transmitter 17,
The input signal is linearly amplified and supplied to the transmission antenna 12 as a required power transmission signal. The transmission antenna 12 converts the transmission signal from the transmitter 17 into a radio signal having the same waveform, frequency, and phase as the radio signal received by the reception antenna 11, and a radio signal in which only the signal magnitude is linearly amplified. To radiate. Here, when the direction of the Doppler measurement transceiver 20 from the moving object is known, an antenna having a directional characteristic can be used as the transmitting antenna 12; Use an antenna or the like.

The Doppler measuring transceiver 20 irradiates the mobile body with its own transmission radio wave, and the received power of the radio wave directly reflected from the mobile body is small. Since the received power of the radio wave transmitted from the transponder 10 for Doppler signal after a delay of just enough is sufficiently large, the received frequency can be measured. The reception frequency has a frequency shift due to the Doppler effect. In this manner, the Doppler measuring transceiver 20 can measure the Doppler frequency based on the moving speed of the moving object or the distance from the moving object (assuming that the delay time τ is known). .

When the Doppler signal transponder 10 is used, when the transmission and reception timings of the # 1 and # 2 Doppler measuring transceivers 5 and 6 are as shown in FIG. 3B, two transmission waves are simultaneously transmitted. Since it never reaches the transponder and has the same frequency, there is no problem with one transponder. However, when the transmission / reception timing is as shown in FIG. 3A, there is a possibility that two transmission waves may reach the transponder at the same time. In this case, the transmission waves operate individually with the two received frequencies f ₁ and f _2. It is desirable to mount two transponders. Note Since the two transmission waves stochastically is small can reach simultaneously, even if one of the transponders, the reception wave of frequency f _1, f ₂ having reached at different times, as the frequency f _1, f ₂ can be transmitted as two response waves, respectively, so that the # 1 and # 2 Doppler measurement transceivers 5 and 6 can use the two transponders from one transponder in most areas, as well as the directly reflected waves. Each measurement can be performed by the response wave.

As described above, according to the third embodiment, the Doppler measuring transceiver installed at the observation point is mounted on the moving target even when sufficient receiving power cannot be obtained directly from the moving target. A sufficient reception power is obtained by receiving the response wave from the transponder, and the measurement can be performed as in the case of the directly reflected wave.

[0039]

As described above, according to the present invention, the antennas are installed so as to have the antenna directivity including the shielding area of the radar radio wave within the own area from different positions.
A radio wave of a predetermined frequency with a predetermined pulse width is transmitted by the antenna directivity characteristic at a predetermined period, a reflected radio wave from a moving target existing within its own coverage area is received, and a Doppler frequency based on a moving speed of the moving target is received. A plurality of Doppler measurement transmitting and receiving means for measuring the distance from the installation position of the mobile object to the moving target, and a Doppler frequency and a moving target which are measured by the plurality of Doppler measuring transmitting and receiving means, respectively. Target speed / position calculating means for sequentially calculating the speed and predicted position of the moving target within the radar radio shielding area based on the distance information is provided, so that the conventional marine surveillance radar system or the like When performing tracking of a target, the target tracking operation is continued even in a water area where radar information cannot be obtained due to a radar shielding area such as an island shade,
There is an effect that a trend of a ship or the like can be grasped.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a radar shielding area support device according to Embodiments 1 and 2 of the present invention.

FIG. 2 is a diagram illustrating an example of installation positions and directional characteristics of # 1 and # 2 Doppler measurement receivers in FIG. 1;

FIG. 3 is a diagram illustrating transmission and reception timings of the # 1 and # 2 Doppler measurement transceivers of FIG. 1;

FIG. 4 is a diagram illustrating a calculation method of a target speed / position calculation unit in FIG. 1;

FIG. 5 is a flowchart illustrating the operation of the radar occlusion support apparatus of FIG. 1;

FIG. 6 is a diagram illustrating a configuration of a transponder for a Doppler signal according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a radar covered area and a radar shielded area.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 radar device 2 target tracking means 3 display device 4 target tracking display device using radar 5 # 1 Doppler measurement transceiver 6 # 2 Doppler measurement transceiver 7 target speed / position calculation means 8 radar shielding area support device 10 Transponder for Doppler signal

Claims (7)

[Claims] An antenna directional characteristic including radar shielding areas from different positions within its own coverage area, and a radio wave of a predetermined frequency and a predetermined pulse width at a predetermined period, respectively. Sent by
Receives reflected radio waves from a moving target existing in its own coverage area, measures the Doppler frequency based on the moving speed of the moving target, and measures the distance from its own installation position to the moving target. Doppler measurement transmission / reception means, based on information of the Doppler frequency and the distance to the moving target measured by the plurality of Doppler measurement transmission / reception means, respectively, based on the speed and prediction of the moving target within the radar radio wave shielding area. A radar shielding area support apparatus, comprising: a target speed / position calculating means for sequentially calculating a position. 2. The target velocity / position calculating means averages information on the Doppler frequency and the distance to the moving target measured by the plurality of Doppler measuring transmitting / receiving means a plurality of times, respectively, and the averaging process is performed. 2. The radar shielding area support apparatus according to claim 1, wherein the speed and the predicted position of the moving target within the shielding area of the radar radio wave are sequentially calculated based on the processed information of the Doppler frequency and the distance. 3. The target velocity / position calculating means starts from a radar detection position before the moving target enters the radar shielding area, and uses the next Doppler frequency information based on the Doppler frequency obtained at the start point. By repeating the operation of predicting the position where the frequency is obtained and then predicting the position where the next Doppler frequency is obtained based on the speed information based on the Doppler frequency obtained at the predicted position, the movement within the radar shielding area is repeated. 3. The radar shielding area support apparatus according to claim 1, wherein the speed and the predicted position of the target are sequentially calculated. 4. The target velocity / position calculating means predicts a position at which the next Doppler frequency is obtained, and measures the position at the time when each of the plurality of Doppler measuring transmitting / receiving means obtains the next Doppler frequency. The radar shielding area support apparatus according to claim 1, 2, or 3, wherein error correction of the predicted position is performed based on distance information from the set installation position to the moving target. 5. The transmission / reception means for Doppler measurement transmits radio waves of a predetermined pulse width at synchronized transmission times, and sets different transmission frequencies to avoid mutual interference of radio waves. The radar shielding area support apparatus according to any one of claims 1 to 4, wherein: 6. The plurality of Doppler transmitting / receiving units transmit radio waves of the same frequency only at transmission times assigned to themselves, alternately or in a predetermined order, from transmission times of a predetermined period, and The radar shielding area support apparatus according to any one of claims 1 to 5, wherein mutual interference is avoided. 7. The plurality of Doppler measurement transmitting / receiving means, instead of receiving directly reflected radio waves from a moving target existing in its own area, a transponder for a Doppler signal mounted on the moving target. The radar shielded area support apparatus according to any one of claims 1 to 6, wherein the apparatus receives a radio wave transmitted in response to the transmitted radio wave.