JP3379483B2 - Radar equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly to a radar device effective for detecting and measuring the position of a target such as a helicopter hovering.

[0002]

2. Description of the Related Art A radar device is an electronic device that radiates a radio wave to a target object and receives the reflected wave to detect or determine the presence or absence of the target object and its position, and is used for many purposes. .

For example, it is known that the detection of a helicopter during hovering can be distinguished from other targets because the radar reception signal has a wide frequency spectrum due to its rotor blades. FIG. 12 shows an example of a strong reflection signal received when a blade (rotary blade) of a helicopter during hover passes through an axis perpendicular to the radar and helicopter axes. FIG. 13 is a spectrum of the signal of FIG. 12 viewed on the frequency axis.

A radar signal processing device for identifying a helicopter from the spread of the spectrum as shown in FIG. 13 is disclosed in, for example, Japanese Utility Model Laid-Open No. 63-90181.
Such a conventional radar reception signal has a configuration as shown in FIG. That is, the pulse Doppler filter 141 to which the radar reception signal is input, the constant false alarm probability circuit 142, the frequency axis OR circuit 143, the gate circuit 144, the comparator 145 for comparing the output of the pulse Doppler filter 141 and the reference value 146, and And a zero Doppler detection circuit 147. The output of the zero Doppler detection circuit 147 controls the gate circuit 144 to send the output to a display (not shown).

This conventional radar signal processing apparatus uses a received signal reflected from a target, clutter or the like, which will be described later with reference to FIG.
Amplitude information in the distance direction is obtained for each filter bank by the pulse Doppler filter shown in, and the target is identified by the Doppler characteristic of the reflected object based on this information.

[0006]

The problem of the above-mentioned prior art is that the circuit configuration of the antenna becomes complicated in order to improve the accuracy of position measurement. The reason will be described below.

From the helicopter during hover, FIG.
As shown in FIG. 5, the rotation of the blade provides a periodic reception signal. To detect a helicopter while hovering,
An observation time of at least one cycle of blade rotation is required, which requires a radiation pattern with a wide beam width. However, since the beam width is proportional to the angle measurement accuracy, a wide beam width deteriorates the position measurement accuracy.

Therefore, as a means for improving the position measurement accuracy, Japanese Patent No. 2828336 (Japanese Unexamined Patent Publication No. 3-1727).
No. 88) discloses "Doppler Radar for Helicopter Detection and Position Measurement", but there is a monopulse angle measurement, reception multi-beam, etc., but this complicates the structure and circuit configuration of the antenna and is expensive.

For example, FIG. 15 shows a block diagram of a radar device for performing monopulse angle measurement. This radar device includes an antenna 150, a circulator 151, a transmitter 152, receivers 153 and 154, a signal processing device 155, and an indicator 1.
It consists of 56.

The antenna 150 is composed of a plurality of antenna elements 1.
50a, distribution combiner 150b, and sum / difference distribution combiner 15
Has 0c. The signal processing device 155 also has a target identification circuit 155a and a position measurement circuit 155b. That is, in the case of monopulse angle measurement, the sum / difference distribution / combining circuit 150c is required to form the pattern of the sum beam and the difference beam, and the receiving system for each of the sum and the difference is required. As above, the complexity is as described above.

Further, the radar device using the receiving multi-beam shown in FIG. 16 includes a transmitting antenna 160, complicated receiving antennas 161a to 161d, a transmitter 162, and a receiver 16 corresponding to each receiving antenna 161a to 161d.
3a to 163d, the signal processing device 164, and the display 165.
It is composed of

The signal processing device 164 is provided for each receiver 163a.
-163d connected to target identification circuits 164a-164
It has d and a position measuring circuit 164e. As the antenna, an antenna having a wide beam width is used as the transmitting antenna 160, and an antenna having a narrow beam width is used as the receiving antennas 161a to 161d. Receiving antennas 161a-16
A plurality of 1d's are required to cover the transmission beam width. Further, it is necessary to use a plurality of receivers 163a to 163d and target identification circuits 164a to 164d of the signal processing device 164 corresponding to the receiving antennas 161a to 161d. Therefore, there is a problem that the circuit configuration becomes complicated and the structure becomes large.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a radar apparatus suitable for detecting and measuring the position of a helicopter during hovering by using an antenna that is simple, compact and lightweight. It is to be.

[0014]

In order to solve the above-mentioned problems, the radar device according to the present invention adopts the following characteristic structure.

(1) Radiation pattern of 360 ° azimuth all around
An antenna formed by one lobe and one null
Having the antenna mechanically or electronically in the azimuth direction
Rotate the lobe part of the radiation pattern of the antenna
Identification means for detecting and identifying a target from the received signal of
And the target position from the received signal of the null part of the antenna
With target processing means consisting of position measuring means for measuring
A radar device comprising:

(2) A plurality of antennas are used as the antenna.
To the antenna element, the phase shifter, and the antenna element or
And a distributor / combiner for distributing and synthesizing signals from the analog elements.
The radar device according to (1) above.

(3) The phase shifter includes the plurality of antennas.
Connected to the rest of the antenna elements except one of the elements
The radar device according to (2) above.

(4) Support the distributor / combiner of the antenna.
Connected to the transmitter and receiver via a curator
The radar device according to (2) above.

(5) A dipole as the antenna element
The above (1), (2), (3) using an antenna or
The radar device according to (4).

(6) A pin diode is used as the phase shifter.
According to the above (2) radar device using a digital phase shifter
Place

(7) First and second antennas are provided.
A pair of antennas is used, and the circular
Supply the transmission signal to the second antenna.
Signal of the phase shifter and the circulator by connecting the phase shifter
Of (1) above, which inputs the signal to the receiver via a combiner
apparatus.

(8) The first antenna is omnidirectional
Rays of the above (7) using one having a radiation pattern
Da device.

[0023]

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a radar device according to the present invention will be described in detail below with reference to the accompanying drawings.

First, FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a radar device according to the present invention. The radar device of FIG. 1 includes an antenna 1, a circulator 6, a transmitter 7, a receiver 8, a signal processing device 9 and a display 12. The antenna 1 has a plurality of antenna elements 2, phase shifters 3, 4 and a distributor / combiner 5. The signal processing device 9 also includes a target identifying circuit 10 and a position measuring circuit 11.

The phase shifters 3 and 4 change the phase of the antenna element 2. The distributor / combiner 5 distributes power to each antenna element 2 and combines the power. The antenna 1 has a function of mechanically rotating by a rotation mechanism (not shown). The circulator 6 receives the transmission signal Tx from the transmitter 7 and the receiver 8
The received signal Rx is separated. The transmitter 7 transmits the transmission signal Tx
Is output. The receiver 8 detects the received RF (radio frequency) signal Rx and outputs a video signal. Target identification circuit 1
0 identifies a target (eg, helicopter). The position measuring circuit 11 measures the position of the target. Display 1
2 displays information detected by the signal processing device 9, that is, the target identifying circuit 10 and the position measuring circuit 11.

Next, the operation of the radar device of FIG. 1 will be described. The transmission signal Tx output from the transmitter 7 is input to the distributor / combiner 5 in the antenna 1 via the circulator 6. The distributor / combiner 5 distributes / combines electric power to each antenna element 2. Either equal distribution or non-uniform distribution may be used to obtain a desired radiation pattern.
The transmission signals distributed by the distributor / combiner 5 are given phase shift amounts φ1 and φ2 by the phase shifters 3 and 4, and the phase between the three antenna elements 2 is adjusted. Pin (PIN) for phase adjustment
A digital phase shifter using a diode may be used, but the phase may be changed by adjusting the length of the pattern on the cable or the RF substrate. Further, there may be a line whose phase is not adjusted.

The purpose of the phase adjustment by the phase shifters 3 and 4 is to obtain a desired combined pattern by the antenna element 2. The signals whose phases have been adjusted by the phase shifters 3 and 4 are input to the antenna element 2 and radiated from the antenna element 2 into space. The present invention requires a radiation pattern with a wide beamwidth. Therefore, for the antenna element 2, for example, a dipole antenna or the like that is nearly omnidirectional is used. In addition to the dipole antenna, it is needless to say that another well-known antenna having a radiation pattern having a wide beam width may be used.

A desired composite pattern can be obtained by arranging a plurality (three in the example of FIG. 1) of the antenna elements 2 described above and adjusting the phases thereof. Figure 3
An example of a combined pattern of the antenna element 2 having a desired directivity is shown in FIG. A signal radiated from the antenna 1 to the space is reflected by a target, clutter or the like, and is received by the antenna 1 as a reception signal. This state is shown in FIG. In this example, there is a first target such as a helicopter, a second target that is a moving target, and clutter. As shown in FIG. 4, since the antenna 1 of the present invention has a wide lobe, it receives all signals such as targets and clutter existing in directions other than the null point of the beam.

Next, reception of a signal received by the antenna 1 will be described. The received signal is the antenna element 2
Are combined by the distributor / combiner 5 via the phase shifters 3 and 4, and further input to the receiver 8 as a reception signal Rx through the circulator 6. The receiver 8 detects the received RF signal and sends it to the signal processing device 9 as a video signal.

In the signal processing device 9, for example, a target identifying circuit 10 as shown in FIG. 14 identifies a helicopter (first target), a moving target (second target) other than the helicopter, clutter, and the like. The target identifying circuit 10 has amplitude information in the distance direction (horizontal axis in FIG. 5) for each filter bank by a pulse Doppler filter as shown in FIG. 5, for example. Based on this information, the filters are selected and identified in consideration of the Doppler characteristics of each target and clutter. Although the position of the target cannot be specified at this point, it is possible to detect the presence of the target.

In the example of FIG. 4, the helicopter, the moving target and the clutter are all received at points other than the null point of the radiation pattern of the antenna 1. Figure 5
4 shows amplitude information in the distance direction for each filter bank obtained based on the received signal received in the state of FIG.
Next, in FIG. 6, the antenna 1 rotates clockwise from the state of FIG. 4, the helicopter (first target) coincides with the null point of the radiation pattern of the antenna 1, and the moving target (first target) 2 target) and clutter are received at a point other than the null point of the radiation pattern of the antenna 1.

When the target is received at the null point, as shown in FIG. 7, the reference value of the signal level is set, and when the reference value is exceeded, there is a signal, and when the received signal is smaller than the reference value, the signal is output. Judge as none. The level of the reference value is set to an optimum value depending on the required position determination accuracy and S / N (signal to noise ratio). FIG. 8 shows the received signal R received in the state of FIG.
The amplitude direction in the distance direction for each filter bank obtained based on x is shown. In the state of FIG. 6, since the helicopter (first target) coincides with the null point of the radiation pattern of the antenna 1, the reception level becomes smaller than the reference value, and as shown in FIG. 8, there is no helicopter amplitude information.

Next, the position measuring circuit 11 compares the received signal in the state shown in FIG. 4 with the received signal in the state shown in FIG. Then, it is detected that the target exists in the direction in which the received signal level becomes smaller. For example, the received signal of the helicopter during hovering is as shown in FIG. This location information is
It is sent from the position measuring circuit 11 to a display (for example, a CRT screen) 12 and displayed there.

FIG. 10 shows an example in which a plurality of helicopters are present. In such a case, each helicopter can be separated and identified by increasing the distance resolution of the radar device. The received signal of each target varies depending on the distance, and is as shown in FIG. It can be detected that the first and second targets exist in the direction of bearing 1, and the third target exists in the direction of bearing 2.

Next, a second embodiment of the radar device according to the present invention will be described. FIG. 2 is a block diagram of the main part of the second embodiment. The radar device of FIG. 2 includes two antennas 13 and 14. A transmitter 7 and a combiner 17 are connected to the antenna 13 via a circulator 16. The antenna 14 includes a phase shifter 15 and a combiner 1
7 is connected. The receiver 8 is connected to the combiner 17.

The antenna 13 has an omnidirectional radiation pattern. The circulator 1 transmits the transmission signal from the transmitter 7.
The signal is received via 6 and radiates this transmission signal in the entire 360 ° azimuth. The signal received (reflected) from the target is
It is received by both antennas 13 and 14. Antenna 1
The signal received by 3 is input to the combiner 17 via the circulator 16. On the other hand, the received signal received by the antenna 14 is phase-adjusted by the phase shifter 15 and input to the combiner 17. The combiner 17 combines the received signals received by the antennas 13 and 14 and sends them to the receiver 8. still,
The signal processing device and the display connected to the subsequent stage of the receiver 8 may be the same as the corresponding device of FIG.

The radiation pattern of the antenna 14 has a directivity with a narrow beam width, and by adjusting the amount of phase shift by the phase shifter 15, the combined reception pattern of the antennas 13 and 14 becomes one lobe. Form a radiation pattern with one null point.

Although the preferred embodiment of the radar device according to the present invention has been described above, this is merely an example, and it is needless to say that various modifications can be made according to a specific application.

[0040]

As can be understood from the above description, according to the radar device of the present invention, it is possible to detect and measure the position of a target such as a helicopter while hovering by using an antenna that is small and lightweight and has a simple circuit configuration. Is. The reason is,
The radar device according to the present invention uses an antenna having a radiation pattern whose radiation pattern covers the entire circumference of 360 ° at one lobe and one null point, detects a target with a single lobe of a wide beam, and detects the position of the beam. This is because the antenna configuration is simplified because the measurement is performed at the null point, and the circuit configuration of the reception system and the target signal processing device can be simplified accordingly.

[Brief description of drawings]

FIG. 1 is a block diagram of a preferred embodiment of a radar device according to the present invention.

FIG. 2 is a block diagram of a main part of another preferred embodiment of the radar device according to the present invention.

FIG. 3 is a diagram showing a radiation pattern of an antenna of the radar device according to the present invention.

FIG. 4 is a diagram showing a positional relationship between a radiation pattern of an antenna and a reflector of a radar device according to the present invention.

FIG. 5 is a diagram showing a Doppler characteristic of a received signal.

6 is a diagram showing a positional relationship between a null point of a radiation pattern and a reflector when the antenna is rotated from the position shown in FIG.

FIG. 7 is an explanatory diagram of a received signal at a null point of a radiation pattern.

8 is a diagram showing the Doppler characteristic of the received signal in the state of FIG.

FIG. 9 is a diagram showing a received signal when the null point of the radiation pattern of the antenna coincides with the azimuth of the helicopter during hovering.

FIG. 10 is a diagram showing a positional relationship between a radiation pattern and a plurality of helicopters.

FIG. 11 is a diagram showing the received signal level in the case of FIG. 10 as azimuth versus distance.

FIG. 12 is a diagram showing the relationship between time and received signal by a helicopter during hovering.

FIG. 13 is a diagram showing a spectrum of a received signal from a helicopter during hovering.

FIG. 14 is a block diagram of a conventional target identifying circuit.

FIG. 15 is a block diagram of a radar device that performs monopulse angle measurement.

FIG. 16 is a block diagram of a radar device that uses received multi-beams.

[Explanation of symbols]

1, 13, 14 antenna 2 antenna elements 3,4,15 Phase shifter 5 distribution synthesizer 6, 16 circulator 7 transmitter 8 receiver 9 Signal processing device 12 Display 17 synthesizer

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-19040 (JP, A) JP-A-63-44188 (JP, A) JP-A-5-2068 (JP, A) JP-A-6- 59030 (JP, A) JP-A-4-108201 (JP, A) Actual development Sho 63-90181 (JP, U) Actual development Sho 63-10476 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01S 3/00-17/88

Claims (8)

(57) [Claims] 1. A radiation pattern of 360 ° in all directions is one.
With an antenna formed of one lobe and one null,
Rotate the antenna mechanically or electronically in the azimuth direction.
The received signal of the lobe part of the radiation pattern of the antenna.
The target identification means for detecting and identifying the target from the
The position of the target is measured from the received signal of the null part of the antenna.
Comprising target processing means comprising position measuring means
A radar device characterized by. 2. A plurality of antenna elements as the antenna
And a phase shifter and to or from the antenna element
And a distributor / combiner for distributing and synthesizing signals from
The radar device according to claim 1, wherein the radar device is a radar device. 3. The phase shifter includes a plurality of antenna elements of the plurality of antenna elements.
Must be connected to the rest of the antenna elements except one
The radar device according to claim 2, wherein: 4. A circular combiner for the antenna
Connected to the transmitter and receiver via a transmitter
The radar device according to claim 2, wherein: 5. A dipole antenna as the antenna element
5. The method of claim 1, 2, 3 or 4 characterized in that
The radar device according to 1. 6. A demultiplexer using a pin diode as the phase shifter.
3. The method according to claim 2, wherein a digital phase shifter is used.
On-board radar device. 7. A pair of first and second antennas serving as the antenna
Use an antenna and attach a circulator to the first antenna
A transmission signal is supplied via the phase shifter to the second antenna.
Connect and combine the signals of the phase shifter and the circulator
Input to a receiver via a receiver.
The radar device according to 1. 8. An omnidirectional radiation pattern as the first antenna.
A device having a turn is used.
7. The radar device according to 7.