JPH01277724A - Target detector - Google Patents

Abstract

PURPOSE:To enhance the detection probability of a metal target such as a moving vehicle, by calculating background intensity at the initial stage of the searching of the target and setting the same as a threshold value. CONSTITUTION:A target detector 9 begins to operate when it reaches specific altitude and a searching visual field 10 is moved according to a spiral searching locus. At this time, a change-over device 3 connects an amplifier 2 to an average value calculation circuit 5 which in turn calculates the average value of a light receiving signal (b) on the basis of the average intensity calculation control signal (d) sent from a control signal generator 4. Said value becomes the signal intensity corresponding to the radiation temp. of a background. The average value is outputted to a hold circuit 6 as an average intensity signal (g) and an average intensity hold signal (h) is outputted to a comparator 7 as a refer ence signal. Thereafter, the amplifier 2 is connected to the comparator 7 and the light receiving signal (b) is compared by the comparator 7. When a vehicle 12 is present within a searching locus 11, the temp. of an engine is high and, therefore, a polarity judge device 8 shows positive and the vehicle target is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a target detection device, and particularly to a target detection device that scans the ground from above with a fixed field of view to identify metal targets on the ground (for example, armored vehicles, etc.).
The present invention relates to a passive target detection device that detects and discriminates moving vehicles such as tanks.

[Prior Art] Conventionally, this type of target detection device has the following features, as shown in FIG.
A detector signal a corresponding to the radiated infrared rays received by the infrared detector 1 is amplified and passed through filter means in an amplifier 2, and then output as a light reception signal. This received light signal is compared in intensity by a comparator 4 with a predetermined reference signal outputted from a reference signal generator 13 using the theoretical received light intensity as a parameter.

Then, when a comparison result 1 indicating that both signal strengths substantially match within a certain variation range is output, the target detector 15 outputs a target detection signal m.

[Interval point to be solved] The conventional target detection device described above performs target detection identification by comparing the received light signal strength and the reference signal strength. That is, since a running vehicle emits strong infrared rays from its engine, etc., the intensity of the received light signal is greater than the intensity of the received light signal in the background (the radiation temperature of the ground is approximately 290K).

Therefore, a predetermined threshold (reference signal) is set, and when the received light signal is greater than this threshold, it is determined that the vehicle is a target.

However, since the received light intensity varies depending on the weather, atmospheric conditions, distance between targets, ground conditions, etc., it is extremely difficult to theoretically determine an accurate threshold in advance.
Moreover, the threshold had to be reset for each operation.

Therefore, due to the inaccuracy of the threshold value, there is a drawback that a target may not be detected even though it exists, or another object may be erroneously detected.

The present invention has been made in view of the above-mentioned problems, and it is difficult to obtain an accurate threshold value in advance by determining the background intensity at the initial stage of target search and setting the determined background intensity as the threshold value. Another object of the present invention is to provide a target detection device that eliminates the trouble of resetting a threshold value each time it is operated, and improves the probability of detecting a metal target such as a moving vehicle.

[Means for Solving Problems] In order to achieve the above object, the target detection device of the present invention includes an infrared detector that receives radiated infrared rays, an amplifier that amplifies the output signal of this infrared detector and outputs a received light signal, and a switching control. a control signal generating means for outputting a signal and an average intensity calculation control signal; a switching means for switching and outputting the light reception signal to a first switching output or a second switching output according to the switching control signal; an average value calculation means for outputting an average intensity signal according to the average intensity calculation control signal when the switching output is supplied; and a holding means for holding the average intensity signal and outputting an average intensity hold signal;
Comparing means for comparing the magnitude of the second switching output and the average strength halt signal and outputting a comparison result, and polarity determining means for outputting a polarity output signal indicating a different polarity according to the comparison result. The composition is as follows.

[Example] Next, an example of the present invention will be described with reference to FIG.

FIG. 1 shows a block diagram of one embodiment of the present invention.

In this figure, the infrared detector 1 and amplifier 2 are the same as conventional ones. 3 is a switch that switches and outputs the light reception signal from the VJ intensifier 2 to the first switching output e or the second switching output 5, and 4 outputs a switching control signal and an average intensity calculation control signal d. It is a control signal generator. 5 is the first
an average value calculation circuit that outputs an average intensity signal g according to an average intensity calculation control signal d when the switching output e is supplied;
6 is a hold circuit that holds the average strength signal g and outputs the average strength hold signal; 7 is a hold circuit that compares the magnitude of the average strength hold signal g with the second switching output f and outputs the comparison result i. The comparator 8 is a polarity determiner that outputs a polarity output signal J indicating a different polarity depending on the comparison result i.

Next, a case where a spiral target search is performed using a target detection device having one or more configurations will be described with reference to FIG.

When the target detection device 9 reaches a specific altitude, it starts operating and moves the search field of view 10 along a search trajectory 11 in the form of a swivel. At this time, the switch 3 connects the amplifier 2 and the average value calculation circuit 5, and the average value calculation circuit 5 scans the beam based on the average intensity calculation control signal d sent from the control signal generator 4. The average value of the received light signal is determined over at least one rotation of the light receiving signal. This value is a signal strength corresponding to the background radiation temperature.

Further, this average value is output as an average strength signal g to the halt circuit 6, and the halt circuit 6 outputs the average strength halt signal g to the comparator 7 as a reference signal for signal strength.

Thereafter, a switching signal C is sent to either the control signal generator 4 or the switching device 3, the amplifier 2 and the comparator 7 are connected, and the received light signal is sent to the comparator 7 as a second switching output f. Comparator 7 compares the previously held average strength halt signal with the second
The switching output f is compared with the switching output f, and the comparison result i is output.

If the received target signal strength is greater than the average value, the polarity determiner 8 outputs a positive polarity output signal j, and if it is smaller than the average value, it outputs a negative polarity output signal j.

At this time, if the vehicle 12 is present within the search trajectory 11, the received strength is greater than the reference signal and the polarity determiner 8 indicates positive because the engine part of the vehicle is hot and is higher than the radiation temperature of the ground. If the polarity determiner 8 indicates positive, it means that the vehicle target has been detected.

[Effects of the Invention] As explained above, the present invention automatically calculates the average value of the signal coming from the background at the initial stage when the device is activated and starts searching for a target, and uses this as a standard for later signal strength comparison. By doing so, it is possible to eliminate the unreliability of signal strength that conventionally required setting in advance and the hassle of setting it, relax operational restrictions such as weather, terrain, time of day, etc., and improve the accuracy of vehicle target detection. It has the effect of being able to improve

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of a spiral target search, and FIG. 3 is a block diagram of a conventional example. 1: Infrared detector 2; Amplifier 3; Switcher 4: Control signal generator 5 Average value calculation circuit 6, Halt circuit 7, Comparator 8: Polarity determiner Representative Patent attorney Kihei Watanabe Figure 1 Figure 2 So...

Claims (1)

[Claims] an infrared detector that receives radiated infrared rays; an amplifier that amplifies the output signal of the infrared detector and outputs a received light signal; a control signal generating means that outputs a switching control signal and an average intensity calculation control signal; a switching means for switching and outputting the received light signal to a first switching output or a second switching output; and outputting an average intensity signal according to the average intensity calculation control signal when the first switching output is supplied. an average value calculation means, a holding means for holding the average intensity signal and outputting an average intensity hold signal, and a comparison means for comparing the magnitude of the second switching output and the average intensity hold signal and outputting a comparison result. and polarity determining means for outputting a polarity output signal indicating a different polarity depending on the comparison result.