JPH06130145A - Radar signal processor - Google Patents

Abstract

PURPOSE:To allow easy detection and tracking even of a target having small amplitude of reflection signal by invalidating distinct noises in each pixel amplitude information of a scan screen and then storing the invalidated noises for each scan screen. CONSTITUTION:Pixel information binarized at a noise removing section 11 is stored at a pixel information storing section 12 for each scan screen and an arbitrary valid pixel is specified as an imaginary target from pixel information of initial scan screen at an imaginary target specifying section 13. An imaginary motion path selecting section 14 selects an imaginary motion path optimal for target detection which is then delivered to an identical imaginary target extracting section 15. A target probability operating section 16 then counts the number N of valid pixels extracted at section 15 and operates a probability where the imaginary target is equal to a true target based on the relationship between the counted number N and an observed number M of prescribed scan screens. Finally, a target detection/tracking processing section 17 makes a decision that an imaginary target having a target probability higher than a prescribed value represents a true target.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to detection of a target from amplitude information of a plurality of scan screens obtained from radar reception signals,
The present invention relates to a radar signal processing device for tracking.

[0002]

2. Description of the Related Art Generally, a radar signal processing device for detecting and tracking a target detects the target from a reference amplitude value independently set for each scan screen, and then performs tracking. In this method, when the amplitude of the target reflection signal is large, the target detection efficiency is high, and the false alarm probability is small, there is almost no noise remaining on the scan screen. It is possible to recognize and track.

However, for example, low RCS (radar
(Cross Section: Radar Reflection Cross Section) When detecting a target with a small reflected signal amplitude such as a target, the reference amplitude value must be set extremely low. In this case, the noise remaining on the scan screen increases (for example, in the case of a low RCS target, 10 ⁴ of the normal target). More than double),
This leads to a decrease in target detection efficiency and an increase in false alarm probability. As a result, it becomes difficult to detect the target, and the following tracking process cannot be performed.

[0004]

As described above, in the conventional radar signal processing device, it is difficult to detect and track a target having a small reflected signal amplitude.

The present invention has been made to solve the above problems, and an object thereof is to provide a radar signal processing device capable of easily detecting and tracking even a target having a small reflected signal amplitude.

[0006]

In order to achieve the above object, a radar signal processing apparatus according to the present invention is one in which amplitude information of each pixel of a scan screen sequentially obtained from a radar reception signal is clearly discriminated as noise. Noise canceling means to be invalidated, storage means for accumulating and storing pixel amplitude information passed through this means for each scan screen, and virtual target specifying means for specifying any pixel of the initial scan screen stored in this means as a virtual target. And a virtual movement path of the target to be detected is given in advance, and a virtual target pixel of the initial scan screen is used as a starting point over a continuous prescribed number of scan screens including the initial scan screen stored in the storage means. Assuming a movement path, the effective pixels of pixels on the path
The same virtual target extraction means that determines invalidity and determines and extracts effective pixels as the same virtual target and the number of effective pixels in the same virtual target extracted by this means are obtained, and the virtual target is calculated from this number and the number of observed scan screens. Target probability calculation means for calculating a target probability that is a true target, and target detection and tracking means for performing target detection and tracking by determining that a virtual target having a target probability obtained by this means is a specified value or more is a true target. And is configured.

[0007]

In the radar signal processing apparatus having the above-described structure, the one that is clearly discriminated as noise from the pixel amplitude information of each scan screen is invalidated, and then stored for each scan screen. Then, an arbitrary pixel of the stored initial scan screen is specified as a virtual target, and a virtual motion path starting from the virtual target pixel is assumed across continuous scan screens including the initial scan screen, and on that system road. The validity / invalidity of the pixel located at is determined. If it is an effective pixel, it is determined and extracted as the same virtual target, and the target probability that the virtual target is a true target is calculated from the number and the number of observed scan screens.
If this target probability is greater than or equal to the specified value, the virtual target is determined to be a true target.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIG.

FIG. 1 shows the configuration of a radar signal processing apparatus according to the present invention. In this apparatus, a pixel amplitude information of each pixel of a scan screen sequentially obtained from a radar reception signal by a radar receiver (not shown) is provided. It is given and sent to the noise removing unit 11.

The noise removing unit 11 sets the reference amplitude value Vref for each scan screen, determines that the pixel amplitude information equal to or less than the reference amplitude value Vref in each scan screen is invalid, and determines that other information is valid, and performs binarization processing. . The reference amplitude value Vref is adjusted to a value that invalidates what is clearly discriminated as noise.

The pixel information storage unit 12 includes a noise removal unit 11
The pixel information binarized by is accumulated and stored for each scan screen. The pixel information storage unit 12 uses a frame memory capable of storing pixel information of a plurality of scan screens as one frame for one scan.

The virtual target specifying unit 13 is a pixel information storage unit 12.
The pixel information of the initial scan screen is read from and an arbitrary effective pixel is specified as a virtual target (hereinafter, referred to as a virtual target). In this specification of the virtual target, all effective pixels are usually specified, but only a part of the area may be specified.

The virtual motion path selection unit 14 is a virtual motion path (hereinafter referred to as a virtual motion path) of several types created based on information obtained from a database relating to a detected target, information obtained from other measurement systems, and the like. Information (referred to as a motion path) is stored, a virtual motion path according to the purpose is selected at the time of observation, and the same is sent to the same virtual target extraction unit 15.

The same virtual target extraction unit 15 receives the virtual motion path from the virtual motion path selection unit 14, and sequentially reads the specified number of pieces of pixel information of the scan screen subsequent to the initial scan screen from the storage unit 12. Then, with the virtual target pixel specified on the initial scan screen as the starting point, a virtual motion path on each scan screen is assumed, and valid / invalid pixels of the pixels located on the system path are discriminated, and the effective pixel is set to the same virtual pixel. Judge and extract the target.

The target probability calculator 16 counts the number of effective pixels extracted by the same virtual target extractor 15, and the target probability that the virtual target is a true target is calculated from the relationship between the number of effective pixels and the observed number of specified scan screens. Is calculated. However, if the number of effective pixels is less than the specified value during the observation, the process for the virtual motion path is terminated.

The target detection / tracking processing unit 17 detects a target by determining a virtual target whose target probability obtained by the target probability calculation unit 16 is a specified value or more as a true target, and at the same time, detects the target from its movement path. Realize tracking. In the above configuration,
The operation will be described below with reference to FIGS. 2 and 3.

First, the noise removing unit 11 adjusts the reference amplitude value Vref to a low level so that the pixel corresponding to the low RCS target becomes effective, and in each scan screen,
Pixel information below the reference amplitude value Vref is invalidated, and other pixel information is validated. In this state, the effective pixel has a low RCS.
It is difficult to distinguish between the target and noise.

On the other hand, for the low RCS target, it is possible to predict which direction to move next based on the information obtained from the database relating to the detected target and the information obtained from other measurement systems. In addition, it is necessary to comply with the request of the observer (operator), such as only detecting the target that faces in his or her direction.

Therefore, the pixel information binarized by the noise removing unit 11 is accumulated and stored in the pixel information storage unit 12 for each scan screen, and the virtual target specifying unit 13 arbitrarily validates the pixel information of the initial scan screen. Identify the pixel as a virtual target. Further, the virtual motion path selection unit 14 selects a virtual motion path most suitable for target detection, and supplies it to the same virtual target extraction unit 15.

Here, the processing after the same virtual target extraction unit 15 will be described by way of example assuming a linear motion path for one virtual target. FIG. 2 shows its conceptual diagram. First, in the same virtual target extraction unit 15, the storage unit 1
Scan screen A1, which follows the initial scan screen A0 from 2
Pixel information of A2, ... Is read in order for a specified number of sheets. Then, the virtual target pixel T0 specified on the initial scan screen A0
From the starting point, a virtual linear motion path L on each scan screen A1, A2, ... Is assumed. Validity / invalidity is determined for the pixels T1, T2, ... Positioned on the system path L. If it is an effective pixel, it is determined to be the same virtual target and is extracted.

Next, in the target probability calculation unit 16, the number N of effective pixels extracted by the same virtual target extraction unit 15 is counted, and the virtual target is determined to be true from the relationship between this number N and the observed prescribed scan screen number M. The target probability that is the target of is calculated.
For example, the target probability is defined as follows. [Target probability] = [Number of effective pixels on virtual motion path] / [Number of specified scan screens]

However, in this target probability calculation, if, for example, 25 scan screens are to be processed, and the number of effective pixels determined to be the same virtual target on the 10th scan screen for a certain linear motion path is 0, 11 The evaluation process after the first is terminated. In this way, when the number of effective pixels is less than the specified value during observation, if the processing for the virtual motion path is aborted, the number of calculations can be reduced,
The processing efficiency can be improved.

Finally, in the target detection / tracking processing unit 17, a virtual target whose target probability obtained by the target probability calculating unit 16 is a specified value or more is determined as a true target. Thereby, a low RCS target is detected, and at the same time, target tracking is realized from the movement path thereof. The specified value of the target detection / tracking processing unit 17 is set as follows.

As in the above example, the initial scan screen T0
Consider a case in which a certain effective pixel T0 is specified as a virtual target, and a linear motion path across M scan screens is assumed with this as a starting point. At this time, it is assumed that N-1 or more scan screens among the M-1 scan screens after the initial scan screen have the same virtual target. In this case, the target detection probability and the false alarm probability are calculated by the following equations.

[0025]

[Equation 1]

Here, the respective characteristics of the target detection probability and the false alarm probability obtained from the equations (A) and (B) are as shown in FIG. 3, and normally Pd> Fa. Therefore, the false alarm probability decreases more rapidly as K increases than the target detection probability.
As a result, if N is set to an appropriate value in the above equations (A) and (B), the false alarm probability when the desired target detection probability is obtained can be reduced from Fa. In other words, the specified value can be obtained from N when the false alarm probability is reduced and the desired target detection probability is obtained from the calculation results of the expressions (A) and (B).

Therefore, the radar signal processing apparatus having the above-described configuration has been independently treated even if the false alarm probability increases by improving the detection efficiency of the low amplitude target by setting the reference amplitude value low. Since each scan screen is associated with a virtual motion path and motion information is captured by evaluating the target probability for that path, the detection and tracking of a low-amplitude target can be performed with the false alarm probability finally reduced. realizable. Further, by setting the virtual motion path appropriately, the target motion to be detected can be selected.
Further, the processing amount can be suppressed by evaluating the target probability for each route for each fixed process.

It is needless to say that the present invention is not limited to the above-mentioned embodiments, and that various modifications may be made without departing from the scope of the invention.

[0029]

As described above, according to the present invention, it is possible to provide a radar signal processing device capable of easily detecting and tracking even a target having a small reflected signal amplitude.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a radar signal processing device according to the present invention.

FIG. 2 is a conceptual diagram for explaining processing contents of the embodiment.

FIG. 3 is a characteristic diagram for explaining a relationship between a target detection probability and a false alarm probability in the embodiment.

[Explanation of symbols]

11 ... Noise removal unit, 12 ... Pixel amplitude information storage unit, 13
... virtual target specifying unit, 14 ... virtual motion path selecting unit, 15 ...
Same virtual target extraction unit, 16 ... Target probability calculation unit, 17 ... Target detection and tracking processing unit.

Claims (5)

[Claims] 1. A noise removing means for invalidating the pixel amplitude information of each scan screen which is sequentially obtained from a radar reception signal and which is clearly discriminated as noise, and the pixel amplitude information passed through this means is accumulated for each scan screen. Storage means for storing, virtual target specifying means for specifying an arbitrary pixel of the initial scan screen stored in this means as a virtual target, and a virtual movement path of the detected target is given in advance and stored in the storage means. Assuming a virtual motion path starting from a virtual target pixel of the initial scan screen over a continuous specified number of scan screens including the initial scan screen, the validity / invalidity of the pixels located on the system path is determined, The same virtual target extraction unit that determines and extracts effective pixels as the same virtual target, and the number of effective pixels in the same virtual target extracted by this unit is calculated, And a target probability calculation means for calculating a target probability that the virtual target is a true target from the number of scan screens observed, and a virtual target whose target probability obtained by this means is a specified value or more is determined as a true target. Signal processing apparatus including target detection and tracking means for performing target detection and tracking in step 1. 2. The radar signal processing apparatus according to claim 1, wherein the noise removing means invalidates pixel amplitude information equal to or less than a reference amplitude value set for each scan screen. 3. The radar signal processing device according to claim 1, wherein the target probability calculation means terminates processing for a virtual motion path in which the number of effective pixels is less than a specified value during observation. 4. The radar signal processing apparatus according to claim 1, wherein said storage means includes a frame memory for accumulating and storing the pixel amplitude information as one frame for one scan. 5. Further, a plurality of types of the virtual motion paths are prepared in advance, and a virtual motion path selection means for selecting one virtual motion path according to the purpose and giving it to the same virtual target extraction means is provided. The radar signal processing device according to claim 1.