JPH04120487A - Radar apparatus - Google Patents

Abstract

PURPOSE:To enable execution of excellent observation in accordance with a local difference of environment by generating a gate signal specifying an area on the basis of the azimuth of an antenna and a time from a transmission trigger and by removing or suppressing an unnecessary reflected wave in a specified range. CONSTITUTION:A gate signal generating circuit 12 compares set values of set ranges A and (b) to b' of removal of unnecessary signals with a rotational angle of an antenna 1 and a time from a transmission trigger and outputs/such gate signals G1 and G2 as turn ON within the ranges A and (b) to b' of removal. When a bright-line beam H is within the range A, the signal G1 turns ON, a fast time constant circuit FTC 5 is activated and thereby a component of rain B is suppressed. When the beam H is within the range (b) to b', the signal G2 turns ON, a waveform mixing circuit 13 adds a Karp signal of a Karp generating circuit 11 to a Karp signal of a sensitivity time control circuit STC 9 and gives an output to an intermediate frequency amplifier circuit 4. Thereby a sea clutter G in the range (b) to b' is suppressed more strongly and thus a target F can be observed excellently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device, and more particularly to a radar device equipped with a short-range sea surface reflection suppression function (STC) and a rain and snow suppression function (FTC) for received echoes.

[Prior Art] Figure 3 is a diagram showing the configuration of a conventional marine radar receiver.
In the figure, (1) is an antenna for radar transmission and reception, and (2)
is the rotation means of the antenna (1), (3) is the transmitting/receiving circuit, (
4) is an intermediate frequency amplification circuit, and (5) is an FTC circuit (f
ast time constant circuit
), (6) is a detection circuit, (7) is a video amplification circuit, (8)
is a cathode ray tube, and (9) is an STC circuit (sensitivity time
control circuit).

Next, the operation will be explained. A signal received by the antenna (1) is converted to an intermediate frequency by a transmitting/receiving circuit (3) and amplified by an intermediate frequency amplifying circuit (4).

Further, normally, the signal passes through the FTC (5) as is, is detected by the detection circuit (6), is amplified by the video amplification circuit (7), and is applied to the cathode ray tube (8). However, if it is difficult to see the target due to g-clutter (reflections on the sea surface) appearing near your own ship, the STC circuit (9) is energized and the intermediate frequency amplification circuit (4)
A curved signal for short-range sea surface reflection control is added to the signal to remove g-clutter, and if the target is difficult to see due to rain clouds overlapping the target, the FTC circuit (5) is energized to generate a gentle signal caused by the rain cloud. Ingredients are suppressed.

[Problems to be Solved by the Invention] The conventional radar reception operation as described above is performed as described above, and the function of suppressing g-clutter and rain/snow covers the entire radar scanning area. It was not possible to conduct radar observations based on local differences in weather conditions (rain, snow, etc.).

The present invention has been made to solve this problem, and its purpose is to provide a radar device that can perform radar observation well in accordance with local differences in the environment.

[Means for Solving the Problems] A radar device according to the present invention includes a gate signal generation circuit that generates a gate signal that specifies an area based on the direction of the antenna and/or the time from a transmission trigger, and an amplification path for received echoes. The FTC circuit is provided with an FTC circuit.
The circuit is energized and deenergized by a gate signal from the gate signal generating circuit.

Further, the radar device according to the present invention includes a gate signal generation circuit that generates a gate signal for specifying an area based on the direction of the antenna and/or the time from the transmission trigger, and an STC circuit that generates a curve signal for suppressing short-range sea surface reflection. a curve generation circuit that generates a predetermined curve signal in synchronization with a transmission trigger; and a waveform forming circuit that mixes or switches the curve signal of the STC circuit and the curve signal of the curve generation circuit under suppression of the gate signal. A received signal amplification circuit whose gain or bias is controlled by the output of this waveform forming circuit is provided.

[Function] In the radar device of the present invention, the FTC circuit is energized and deenergized by the gate signal, so if the gate signal is applied only to areas where there is rain and snow, targets buried in rain and snow can be seen more clearly. At the same time, other parts can be observed under normal conditions.

Furthermore, in the radar device according to the present invention, the curve signal of the STC circuit and the curve signal of the curve generation circuit are mixed or switched under the control of the gate signal, and the gain or bias of the received signal amplification circuit is controlled by the output thereof. Even if the receiving gain is suppressed in all directions by the circuit, even if g-clutter remains in a specific direction, stronger suppression can be applied to that direction.

[Example 1] An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a radar receiver of a marine radar device according to an embodiment. In the figure, the same reference numerals as in FIG. Rotational position detection means outputs the rotation angle (θ) of the antenna (1) based on the pulse (EP), and (11) is a predetermined curve signal created as a function of the distance from the radar device in synchronization with the transmission trigger. A curve generation circuit that outputs
(12) is the gate signal (Gl) that specifies the area based on the antenna rotation angle (θ) and the time from the transmission trigger.
, (G2), and (13) is a waveform mixing circuit that mixes each curve signal of the 5TC (9) and the curve generation circuit (11) under the control of the gate signal (G2).

Figure 2 is a diagram showing an example of the display on the cathode ray tube (8), in which (I) is the own ship's position, (H) is the bright line beam synchronized with the rotation angle (θ) of the antenna, and (a) is the bright line beam. (H
) rotation direction, (A) is the removal range of unnecessary signals, (B) is rain or snow, (C) to (F) are targets, (G) is g-clutter, (b to b') is pinched This area is another area where unnecessary signals are removed.

Next, the operation will be explained. First, the gate signal generation circuit (
12) Set unnecessary signal removal ranges (A) and (b to b'). The removal range (A) is set based on, for example, the rotation angle of the antenna (θ) and the time from the transmission trigger (which may be converted from the distance from the own ship), and the removal range (b to b' ) can be set only by the antenna rotation angle (θ).

The gate signal generation circuit (12) compares the set value of the removal range (A) with the rotation angle (θ) of the antenna and the time from the transmission trigger, so as to turn ON within the removal range (A). By outputting the gate signal (G1) and comparing the setting value of the removal range (b to b') and the rotation angle (θ) of the antenna, it is possible to turn ON within the removal range (b to b'). outputs a gate signal (G2).

In this way, when the bright line beam (H) advances and reaches the removal range (A>), the gate signal (GI) is turned ON only inside this removal range (A), so F is turned on only within the removal range (A).
The TC circuit (5) is energized, the rain (B) component is suppressed, and the target object (C) appears more clearly. Furthermore, since the FTC circuit (5) is not energized for the target object (D>), it appears clearly.

As the emission line beam (H) advances further, it reaches the target (E), but since the sea surface reflection suppression effect by the 870 circuit (9) has been effective in all directions in the sea area so far, di-clutter has been well suppressed. and a clear screen is obtained.

However, when reaching the removal range (b to b'), 870 circuits (
Despite the effect of 9), strong di-clutter appears due to waves. By the way, the curve generating means (11) of this embodiment generates a curve signal that suppresses such g-clutter more strongly when superimposed on the curve signal of the 870 circuit (9), and ) rotates further and the bright line beam (H) exceeds the direction of (bo), the gate signal (G2)- turns ON and the waveform mixing circuit (13) converts the curve signal of the 870 circuit (9). The curve signal of the curve generating circuit (11) is added (mixed) to the curve generating circuit (11), and the output thereof is applied to the intermediate frequency amplifying circuit (4). Thereby, the g-clutter (G) within the removal range (b to b') is suppressed more strongly, so that the target object (F) can be observed well.

Then, when the bright line beam (H) crosses the direction of (bo), the gate signal (G2) is turned OFF and the 870 circuit (
Only the curve signal 9) is applied to the intermediate frequency amplification circuit (4), resulting in a normal short-range sea surface reflection suppression display.

In the above embodiment, sea surface reflection suppression control was performed in the intermediate frequency amplification circuit (4), but the transmission/reception circuit (3), the detection circuit (6), the video amplification circuit (7), and other specially provided signal processing Sea surface reflection suppression control may be performed in a circuit (not shown).

Further, in the above embodiment, the waveform mixing circuit (13) has 8
70 circuits (9) curve signals and curve generation circuits (11)
870 circuits (9
) and the curve signal of curve generating circuit (11) may be switched. The curve signal of the curve generation circuit (11) in this case replaces that of the 870 circuit (9).

Further, in the above embodiment, the gate signals (G1) and (G2) are turned on in different areas, but the gate signals (G1) and (G2) may be turned on in some or all areas.

Further, in the above embodiment, the rotating means (2) is connected to the antenna (1).
The case where the antenna (1) is rotated continuously is shown.
The present invention can also be applied to the case of reciprocating the rotation.

[Effects of the Invention] As described above, the present invention can remove or suppress unnecessary reflected waves in a specific range, and therefore has the effect of allowing radar observation to be performed satisfactorily in accordance with local differences in the environment.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a radar receiver of a marine radar device according to an embodiment, Fig. 2 is a diagram showing a display example of a cathode ray tube (8), and Fig. 3 is a diagram showing the configuration of a conventional marine radar receiver. It is a diagram. In the figure, <1) is the antenna, (2) is the rotation means, and (3) is the antenna.
) is a transmitting/receiving circuit, <4) is an intermediate frequency amplification circuit, (5) is an FTC circuit, (6) is a detection circuit, (7) is a video amplification circuit, (8) is a cathode ray tube, (9) is an STC circuit, ( 10)
(11) is a rotational position detection means, (11) is a curve generation circuit, and (1) is a rotational position detection means.
2) is the gate signal diagram

Claims (2)

[Claims] (1) comprising a gate signal generation circuit that generates a gate signal for specifying an area based on the direction of the antenna and/or the time from the transmission trigger; and an FTC circuit provided in the amplification path of the received echo; A radar device characterized in that it is energized and deenergized by a gate signal from a gate signal generating means. (2) A gate signal generation circuit that generates a gate signal that specifies an area based on the antenna direction and/or time from the transmission trigger, an STC circuit that generates a curve signal for suppressing near-field sea reflections, and synchronized with the transmission trigger. a curve generating circuit that generates a predetermined curve signal using the gate signal; a waveform forming circuit that mixes or switches the curve signal of the STC circuit and the curve signal of the curve generating circuit under the control of the gate signal; and the output of the waveform forming circuit. What is claimed is: 1. A radar device comprising: a received signal amplification circuit whose gain or bias is controlled by: