JPH0392783A - Radar signal processor - Google Patents

Abstract

PURPOSE:To achieve a higher detection rate within a clutter area by dividing a unit of a small area into three or more kinds of sections. CONSTITUTION:A threshold determining circuit 1 determines a threshold of the subsequent radar scanning cycle to be a small area unit from an amplitude value of a radar signal 5 to be inputted and a radar target signal 7. A size of a small area unit is determined to be any of three kinds or more by a clutter indicator 8 judged with a clutter area judging circuit 2 and made smaller within a clutter area while larger in a clutter-free area and intermediate therebetween in an uncertain area. Then, a threshold 6 stored in a threshold memory circuit 3 is read out at the subsequent radar scanning cycle and it is kept constant during a period in a small area range with a size thereof being any of three kinds or more as specified by a clutter indicator 9. Therefore, an optimum threshold control suited to an environmental condition of a radar signal is made possible thereby permitting improvements in a target detection rate within the clutter area.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a radar signal processing device, and in particular, the present invention relates to a radar signal processing device that divides a radar coverage area into small areas and performs target detection threshold control for each small area. The present invention relates to a radar signal processing device including a target detection device that detects a target.

[Conventional technology]

Conventionally, in this type of radar signal processing device for target detection, the size of a small area that is a processing unit is divided into uniform units in the distance direction, azimuth direction, and altitude direction over the entire radar coverage area. A threshold storage circuit for threshold control in units of this small area is provided for the entire radar coverage area, and threshold control is also performed in units of this small area.

[Problem to be solved by the invention]

In the target detection processing of the conventional radar signal processing device described above, the threshold value for target detection is the same value within a small area. In this way, if the threshold value is the same within a small area, if the target aircraft and other objects such as ground clutter, weather clutter, or chaff exist simultaneously within the small area, the following There is a problem like this. First, depending on the amplitude of the radar reflection signal, if threshold control is performed to detect as many targets as possible, other clutter may also be detected as false targets, making it impossible to obtain the necessary false target alarm rate. . On the other hand, if threshold control is performed to suppress detection of erroneous targets as much as possible, the target cannot be detected and the target detection rate deteriorates.

To compensate for this drawback, by further reducing the size of the small area, it is possible to subdivide control of the target detection criteria and improve the target detection rate and false target alarm rate, but it is possible to improve the target detection rate and false target alarm rate. However, the capacity of the threshold storage circuit becomes proportionally large, and the two divisions of the clutter region and clutter-free region improve both the target detection rate and the false target alarm rate at the same time. has the disadvantage of having limitations.

[Means to solve the problem]

The radar signal processing device of the present invention divides the radar coverage into a plurality of small areas two-dimensionally or three-dimensionally along the distance, azimuth, and altitude directions, and performs target detection processing on these small areas. Threshold control is performed for target detection in small area units on the amplitude value of the radar signal reflected from the target, and it is determined that there is a target when the amplitude value of the radar signal exceeds the threshold value. The radar signal processing device includes a clutter area identification circuit that receives the radar signal and divides the radar coverage area into a clutter area, a clutter-free area, and an uncertain area, and a clutter area identification circuit that determines the required target detection rate and false target in units of the small area. a threshold determining circuit for determining a threshold for obtaining an alarm rate; and storing the threshold determined by the threshold determining circuit in order to read out the threshold in the next radar scanning cycle. a threshold value storage circuit; and an amplitude comparison circuit that compares the threshold value read from the threshold value storage circuit with the amplitude value of the radar signal and determines that there is a target when the amplitude of the radar signal is greater than the threshold value. The threshold determining circuit makes the size of the small area in the clutter area smaller than the size of the small area in the clutter-free area based on the judgment of the clutter area identification circuit, and the uncertain area is configured to 1 and smaller than the width of the small area in the clutter-free area.
The threshold value is determined for each small area using .

5-1 〔Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. Threshold determination circuit 1 is a circuit that determines a threshold value for each small area of a specified size, clutter area 1 area determination circuit 2 is a circuit that outputs a clutter index for clutter area VA, and threshold value storage. The circuit 3 is a circuit that stores and holds the threshold value until the next radar scanning cycle, and the amplitude comparison circuit 4 is a circuit that compares the radar signal 5 and the threshold value 6 to determine the presence or absence of a target.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Based on the amplitude value of the input radar signal 5 and the radar target signal 7, the threshold value determining circuit 1 determines the threshold value for the next radar scanning cycle in small area units. The unit size of this small area is the clutter index 8 determined by the clutter area determination circuit 2.
One of three or more sizes is determined by , small in the clutter region and thick in the clutter free region −′<
In the uncertain area, the size is intermediate.

The size of the above-mentioned unit size is determined by analyzing the proportion of the average clutter area size in the entire radar coverage area and making sure that it does not greatly exceed the total number of small areas when the unit size is determined uniformly. The number of small areas may be determined so that the number of small areas is as small as possible.

The clutter index 9, which is another output of the clutter area determining circuit 2, is stored in the threshold storage circuit 3 in combination with the threshold value output from the threshold determining circuit 1.

In the next radar scanning cycle, the threshold value 6 stored in the threshold value storage circuit 3 is read out, and during the period of any small area range of three or more sizes specified by the clutter index 9, The threshold is kept constant.

The amplitude comparison circuit 4 compares this constant threshold value 6 with the amplitude data of the input calendar signal 5, and when the amplitude of the input calendar signal 5 is larger than the value of the threshold value 6, a target is placed at that position. It is determined that there is a radar target signal 7, and a radar target signal 7 is generated.

〔Effect of the invention〕

As explained above, the present invention provides a clutter region where the amplitude of the radar signal changes drastically, a clutter-free region where the amplitude value is relatively uniform, and an uncertain region where the amplitude changes intermediate between these regions. By dividing the small area unit into three or more sizes, which is the unit of control processing for the threshold value that becomes the target detection standard, and by dividing the small area unit into three or more types, the threshold It is now possible to perform optimal threshold control according to the environmental conditions of radar signals without significantly increasing the storage capacity of the value storage circuit compared to the storage capacity of conventional devices, resulting in a significant improvement in the target detection rate in clutter areas. This also has the effect of significantly suppressing the false target detection rate.

4

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a radar signal processing device according to the present invention. 1... Threshold determination circuit, 2... Clutter area determination circuit, 3... Threshold storage circuit,
4... Amplitude comparison circuit, 5... Radar signal, 6... Threshold signal, 7... Radar target signal, 8, 9... ...Clutter index.

Claims (1)

[Claims] Radar coverage in distance direction, azimuth direction, and altitude direction 2
Divided into multiple small areas dimensionally or three-dimensionally, and using these small areas as a unit of target detection processing, a threshold value for target detection is set for each small area based on the amplitude value of the radar signal reflected from the target. A radar signal processing device that performs control and determines that a target is present when the amplitude value of the radar signal exceeds a threshold receives the radar signal and divides the radar coverage area into a clutter area, a clutter-free area, and an uncertain area. a threshold determination circuit that determines a threshold for obtaining the required target detection rate and false target alarm rate in units of the small areas; A threshold storage circuit that stores the threshold determined by the threshold determination circuit in order to read the threshold; and a threshold that stores the threshold and the amplitude value of the radar signal read from the threshold storage circuit. and an amplitude comparison circuit that compares and determines that there is a target when the amplitude of the radar signal is larger than a threshold value, and the threshold value determination circuit determines the extent of a small area in the clutter area based on the determination of the clutter area identification circuit. determining a threshold value for each small region, with the uncertainty region being larger than the width of the clutter-free region and smaller than the width of the small region in the clutter-free region; A radar signal processing device characterized by: