JPS6333686A - Low elevation angle target tracking instrument - Google Patents

Abstract

PURPOSE:To track a low elevation angle target with a high accuracy by adding an auxiliary tracking radar instrument with auxiliary tracking antennas having sharp antenna beam directivity in the direction of elevation angle to a tracking radar equipment. CONSTITUTION:An auxiliary tracking radar equipment with auxiliary tracking antennas 81a and 81b having sharp antenna beam directivity in the direction of elevation angle is added to a tracking radar equipment 2. When a low elevation angle target is tracked, the tracking antenna of the instrument 2 and the antennas 81a and 81b are controlled on the basis of an error in the elevation angle of the target obtained by the auxiliary tracking radar instrument. Thus, since the antennas have the sharp beam directivity in the direction of elevation angle, although they receive direct reflected waves from the target, they do not receive the waves reaching after one sea clutter, that is, the waves reaching from reflected image directions. In result, the elevation angle obtained as the output of the auxiliary tracking radar is highly accurate. Thus, the low elevation angle target is tracked with a high accuracy.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for accurately tracking a target at a low elevation angle using a radar device in a radio wave environment where multiple reflections exist, such as at sea. be.

[Conventional technology]

A monopulse method has been generally known as a tracking radar method.

Figure 4 is a principle diagram when a monopulse type tracking radar device is installed on a ship to track a low-elevation target, where (1) is a ship equipped with a tracking radar device, (2) is a tracking radar device, and (3) is a ship equipped with a tracking radar device. ) is the beam in the vertical plane of the antenna of the tracking radar device, f4) is the target, and (5) is the reflected image of the target due to reflection from the sea surface. Figure 5 is a principle diagram showing the principle of error angle detection in a monopulse tracking radar device, where (6) is the sum channel pattern of antennas in the vertical plane, and (7) is the same (difference between antennas in the vertical plane). In Fig. 5, the horizontal axis represents the elevation angle from the antenna center axis, and the vertical axis represents the signal strength, respectively. (6a), (7a)
? (6';') shows the arrival direction of the radio wave from the target +41 and the signal strength of the sum channel and the difference channel in that direction. (7b) shows the arrival direction of the radio wave from the reflected image (5) and its direction. shows the signal strength of the sum channel and the difference channel at .

[Problem that the invention seeks to solve]

Conventional tracking radar is like this, so it is possible to reach the target (4
) is low, the incoming radio waves from the true target and the incoming radio waves from the reflected image (5) are simultaneously received by the beam (3), so in the following equation for calculating the target error angle ΔE, the above (6a ), (6b), (7a), (7
b) It is not possible to obtain the correct target error angle because all the components are included.

There are methods to suppress the uncertainty of such error angles, such as narrowing the antenna beam width to reduce the influence of reflected waves from the sea surface, but this increases the size of the antenna, making it difficult to use tracking radars installed on ships. As a device, there are limitations and inconveniences arise.

The invention was made to eliminate these inconveniences, and its purpose is to accurately track low-elevation targets in a radio wave environment where multiple reflections exist.

[Means for solving problems]

The low-elevation angle target tracking device related to this BAK has an auxiliary tracking radar device having an auxiliary tracking antenna with sharp antenna beam directivity in the elevation direction added to the conventional tracking radar device, and when tracking a low-elevation angle target, the above-mentioned auxiliary tracking radar device is added. The tracking antenna of the tracking radar device and the auxiliary tracking antenna are controlled based on the elevation angle error of the target obtained by the tracking radar.

[Effect]

Since the auxiliary tracking antenna of this invention has sharp beam directivity in the elevation direction, it receives the direct reflected waves from the target, but it receives the radio waves that arrive after being reflected once from the sea surface, that is, the radio waves that arrive from the direction of the reflected image. Not received. Therefore, as a result, the elevation angle error obtained as the output of the auxiliary tracking radar device becomes highly accurate.

〔Example〕

FIG. 1 is a principle diagram showing an embodiment of this invention. (1) Fi
Ship, +21#i tracking radar device, (3) is a beam in the vertical plane of the tracking antenna of the tracking radar device.

(4) is the target, (5) is the reflected image of the target, (81
a) , (llHb) is a monopulse type auxiliary tracking antenna with one axis of elevation of the auxiliary tracking radar, (9a)
is one of the beams in the vertical plane of the auxiliary tracking antenna.
It is one. FIG. 2 is a principle diagram showing an embodiment of the present invention viewed from above. (1), [21, (EH
a), (stb) are the same as in Figure 1, (81C
), (81cl) are the above (8ta), (sob
), (10a), (ta
b), (toe) (+od) is a beam in the horizontal plane of the auxiliary tracking antenna. FIG. 3 is a block diagram showing the internal details of the tracking radar device and the auxiliary radar device O. D is a two-axis monopulse tracking antenna, @ is a circulator that switches between transmitting and receiving.

(to) is the transmitter, @ is the receiver, @ is the angle tracking device # (to) is the distance tracking device, the fin is the switch that switches the elevation angle error signal, @ is the servo that outputs the drive signal to the above tracking antenna CD Amplifier, (81a), (81b)
.

(elc) , (81(1) is the same auxiliary tracking radar as in FIGS. 1 and 2, (82) Fi is the servo amplifier (
A signal switching device that selects one set of outputs according to the azimuth angle output of (to).

(83) is an auxiliary receiver, (84) is a signal that extracts only the signal on the time axis corresponding to the target distance), (8
5) is elevation angle tracking device, (86) &i above auxiliary tracking antenna (sea), (sob), (81C
), (81d) are auxiliary servo amplifiers that output drive signals.

Since this invention is as described above, the transmitter (c)
The thrust force is radiated from the monopulse tracking antenna 211 via the circulator (2). The radio waves reflected from the target (4) are transmitted directly or after being reflected from the sea surface to the above-mentioned tracking antenna Qυ.
The signal is received within the beam width of beam (3) and input to the receiver via the circulator. The output of the receiver @ is input to the angle tracking device (to) and the distance tracking device (1). Direction for angle tracking device (to).

For each elevation, the azimuth angle error and the elevation angle error are extracted from the sum channel and difference channel signals, the azimuth angle error is input to the servo amplifier (to), and the elevation angle error is input to the changeover switch.

The distance tracking device ■ tracks the distance of the target]4) and sends a distance signal to external related equipment, and also sends a distance gate signal (8)
4) Output each to.

On the other hand, the direct wave from the target (4) is captured by the beam (9a) of the auxiliary tracking antenna (8111).

For convenience of explanation, the target direction is beam (9!I) and Fi
(toa) direction, but no matter which direction the target is, the beam (+Oa) ~ (toa) should be widened so that it can be received in all directions of the ship. There is no problem because the target can be tracked.Auxiliary tracking antennas (81a) to (81d)
The output is input to the signal switching device (82).

The signal switching device (82) uses the azimuth output signal of the servo amplifier (to) to switch the auxiliary tracking antennas (81a) to (
81cl) and outputs it to the auxiliary receiver (83). The auxiliary receiver (83) inputs the local oscillator signal generated based on the source oscillator inside the receiver @, operates in synchronization with the receiver @, and switches the signal switching device (
The high frequency signal output of 82) is converted into an intermediate frequency signal, amplified, and output to (84). Goo) (84)
Then, based on the distance gate signal from the distance tracking device (to), only the intermediate frequency signal at the timing corresponding to the target is output to the elevation tracking device (85). Elevation angle tracking device (8
In 5), the elevation angle error is extracted from the two signals of the sum channel and the difference channel and output to the switching switch and auxiliary servo increase@6 (86). The changeover switch @ selects the elevation angle error output from the angle tracking device (c) for high altitude targets, and the elevation angle error output from the elevation angle tracking device (8) for low elevation targets.
Select the elevation angle error output from 5) and output it to the servo amplifier (c). The servo amplifier (to) determines the azimuth and elevation angle of the target (4) using the azimuth angle error and the elevation angle error, and directs the tracking antenna 12υ. Also, in the auxiliary servo amplifier (86), the target f4) is determined by the elevation angle error.
Find the elevation angle of the auxiliary tracking antenna (81a) to (8+
d) direct.

That is, when tracking a target at a low elevation angle, the beam in the vertical plane of the auxiliary tracking antenna (81a to (8+d) is very narrow, so it is affected by the reflected image (5). Therefore, based on the elevation angle error, the tracking antenna 12υ and the auxiliary tracking antenna (ah
If a) to (8+a) are controlled, the target direction will be correctly pointed.

For convenience of explanation, in the above embodiment, the case where the number of auxiliary tracking antennas is four is taken as an example, but as long as the beam in the horizontal plane of the antenna exists all around the azimuth, the number of auxiliary tracking antennas can be any number. good. Furthermore, in the above embodiment, a method was used in which the mechanical axis of the antenna was driven by a servo device in order to direct the center of the antenna beam in an arbitrary direction, but a method that electrically swings the beam like a phased array antenna can also achieve this low elevation angle. This does not impair the original function of the tracking method.

〔Effect of the invention〕

As explained above, in the present invention, by adding an auxiliary tracking radar device having sharp beam directivity only in the elevation direction to a conventional tracking radar device, highly accurate tracking of a low elevation angle target can be expected. In addition, the auxiliary tracking radar device does not require a transmitting function and only needs to have a tracking function in one axis of elevation and elevation, so the overall scale of the device can be kept small5.Furthermore, since it is installed separately from the tracking radar device, It can be mounted relatively low on the ship, making it even less susceptible to the effects of multiple reflections from the sea surface, and making it possible to keep the ship's center of gravity low.

[Brief explanation of the drawing]

FIGS. 1 and 2 are principle diagrams showing an embodiment of this invention,
FIG. 3 is a block diagram of an embodiment of the present invention, FIG. 4 is a principle diagram showing the operation of a conventional tracking radar device, and FIG. 5 is a principle diagram showing the principle of error angle detection in the monopulse method. In the figure, (1) is a ship, (2) is a tracking radar device, (
3) is the antenna beam, (4) is the target + 151Fi reflection, (6) (6a) C6b) is the sum channel pattern, +71 (7a) (7b,) is the difference channel pattern, (9m) is the antenna butter y,
(+0a) (+0b) (+0su(+Oa) is 77
f + pattern, ell is the tracking antenna, @ is the circulator, +23 is the transmitter, 241 is the receiver # (a)
is the angle tracking device, ＼ is the distance tracking device, ＠ is the changeover switch, ＠ is the servo amplifier, (81su(8+b)) (8+su(81d) is the auxiliary tracking antenna, (82)
is a signal switching device, and (83) is an auxiliary receiver. (84) is a game), (85) is an elevation angle tracking device, and (86) is an auxiliary servo amplifier. Note that the same or corresponding parts in the two figures are designated by the same reference numerals. Figure 2 Figure 3

Claims (1)

[Claims] The components include a transmitter, a receiver, an angle tracking device, a distance tracking device, and a tracking radar device that has a tracking antenna that can mechanically or electrically direct a beam in two axes of direction and elevation, and one axis of elevation. A plurality of auxiliary tracking antennas that can mechanically or electrically direct the beam arbitrarily, and an appropriate set of azimuth angle outputs from the following servo amplifier or beam control device are input from the outputs of the plurality of auxiliary tracking antennas. a signal switching device that selects the output of the tracking radar device, an auxiliary receiver that operates by inputting a local signal from the receiver of the tracking radar device, and an auxiliary receiver that inputs a distance gate signal from the distance tracking device of the tracking radar device and operates the auxiliary receiver. a gate that extracts only the target signal of the output signal; an elevation angle tracking device that extracts the elevation angle error from the gate output; and an elevation angle error output of the angle tracking device of the tracking radar device and the elevation angle of the elevation angle tracking device. A changeover switch that selects one of the error outputs, an azimuth angle and an elevation angle at which the tracking antenna beam of the tracking radar device should be directed by the azimuth error output of the angle tracking device of the tracking radar device and the changeover switch output. and an auxiliary servo amplifier or auxiliary beam controller that outputs an elevation angle at which the auxiliary tracking antenna beam should be directed based on the output of the elevation angle tracking device. .