JPH01172788A - Guiding device - Google Patents

Abstract

PURPOSE:To judge whether a peak indicates a target or surface noise by always measuring signal versus noise ratio SN of the peak and comparing it with the threshold of SN to be determined depending on the magnitude of peak brightness. CONSTITUTION:An infrared image pickup device 1 converts an outside image into an analog video signal 2. An A/D convertor 3 samples the signal 2 to output a digital video signal 4. A peak detecting circuit 5 detects the peak brightness from the signal 4 to output peak brightness data 6. An rms measuring circuit 15 operates the dispersion value of the signal 4 to output rms data 16. A dividing circuit 17 obtains the ratio of the data 6/data 16 to output SN data 18. A SN threshold determining circuit 19 determines the threshold of the data 18 based on the data 6 to output SN threshold data 20. A locked-on judging circuit 9 compares the data 18 with the data 20 to output a locked-on signal 10. A binarized threshold determining circuit 7 determines a binarized threshold value from the data 6 to output brightness threshold data 8. Besides, a binarizing circuit 11 and a centroid operation circuit 13 are prepared.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a guidance device for a flying object that tracks a target, and in particular, to prevent erroneous lock-on to a background such as the sea surface when searching for a target. , relates to an infrared projectile guidance device that can increase the probability of hitting a target.

(Summary of the Invention) This invention focuses on the peak signal-to-noise ratio (SN) that appears in a video signal obtained by imaging the outside world in a guidance device for a flying object that tracks a target. The peak luminance is compared with the SN threshold depending on the peak brightness, and if the SN is larger than the threshold, the peak is regarded as a significant target and a lock-on signal is output, locking on to a non-target. The probability is reduced.

(Prior Art) FIG. 4 is a block diagram showing an example of the configuration of a conventional infrared object guidance device using an infrared imaging device,
1 is an infrared imaging device, 2 is an analog video signal, 3 is A
/D converter, 4 is a digital video signal, 5 is a peak detection circuit, 6 is peak luminance data, 7 is a binarization threshold determination circuit, 8 is luminance threshold data, 9 is a lock-on determination circuit, 10 is a A lock-on signal, 11 a binarization circuit, 12 a binary video signal, 13 a center-of-gravity calculation circuit, and 14 a guidance signal.

! ll′! In Figure +4, an infrared image of a target is converted into an analog video signal 2 by an infrared imaging device 1.

Analog video signal 2 is sampled by A/D converter 3 and converted into digital video signal 4. The peak detection circuit 5 receives this digital video signal 4, and
Find the peak brightness at which the brightness level is maximum for each screen,
Output as peak luminance data 6. The lock-on determination circuit 9 compares the peak brightness data 6 with a threshold value representing a target minimum brightness level given in advance, and if the peak brightness data 6 is greater than the threshold value, a lock-on signal 10 is generated.
Output. On the other hand, the binarization threshold determination circuit 7 receives the peak luminance data 6 and converts it into threshold data 8 [peak luminance data 61×C (where C is a predetermined value of 1 or less)] Output as . The binarization circuit 11 receives the lock-on signal 10 and the threshold data 8, and only when the lock-on signal 10 is significant, binarizes the digital video signal 4 using the luminance threshold data 8.
A binary video signal 12 is output. The center of gravity calculation circuit 13 is
It receives the binary video signal 12, calculates the center of gravity of the n region of the target, and outputs it as a guidance signal 14.

(Problems to be Solved by the Invention) In conventional guidance devices of this type, when automatically locking onto a target, locking on is performed by comparing the magnitude of peak brightness with a predetermined threshold value. I was deciding whether or not. Therefore, in order to lock on to a target at a distance, the signal from the target is small, so
It was necessary to set a low threshold. However, on the other hand, if the threshold value is set low, if sea surface noise etc. is large,
There was a problem in that the missile could be locked on to this by mistake, and the projectile could not be guided to the target correctly, but directed towards the sea surface noise.

(Object of the Invention) This invention measures the signal light noise ratio (hereinafter abbreviated as SN) of the peak that appears in the video signal of the target image at the time of determining lock-on to the target, and sets a threshold value for this. An object of the present invention is to provide a guidance device that can significantly reduce the probability of lock-on to sea surface noise or the like other than the target.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an imaging device that converts an image of the outside world into an analog video signal, and samples the analog video signal and outputs it as a digital video signal. a peak detection circuit that detects peak brightness from the digital video signal and outputs it as peak brightness data; a rhos measurement circuit that calculates a variance value of the digital video signal and outputs it as rτns data; a division circuit that calculates the ratio between the peak luminance data and the rlllls data and outputs it as SN data; and an SN threshold determination circuit that determines the threshold of the SN data according to the peak luminance data and outputs it as SNt threshold data. a lock-on determination circuit that compares the SN data with the SN threshold data and outputs a lock-on signal according to the determination result;
a binarization threshold determination circuit that determines a threshold value for digitization and outputs it as luminance threshold data; and a binarization threshold determination circuit that receives the lock-on signal and the luminance threshold data and binarizes the digital video signal. The apparatus is configured to include a binarization circuit and a centroid calculation circuit that calculates the centroid position of the target area from the binarized video data outputted by the binarization circuit and outputs it as a guide signal.

(Function) In the guidance device of the present invention, the digital video signal 4
By measuring the peak brightness and dispersion value of
Find N. Next, an SN threshold value depending on the peak brightness is set so that a high threshold value is used when the peak brightness at this time is small, and a low threshold value is set when the peak brightness is large.

Furthermore, the SN is compared with this SN threshold, and the SN
is greater than the threshold, the peak is considered a significant target and a lock-on signal is output.

Therefore, in the device according to the present invention, the SN of the detected peak is measured, and if the peak brightness is small, it will not lock on unless it has a sufficiently high SN, so it will not lock on to non-targets such as sea surface noise. It is possible to realize a significant reduction in the probability of erroneous lock-on.

(Example) Hereinafter, an example of the guidance device according to the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of one embodiment of the present invention, in which 15 is an rtos measurement circuit, 16 is rms data, 1
7 is a division circuit, 18 is SN data, 19 is an SN threshold determination circuit, and 20 is SNt threshold data. The other circuit parts are the same as in the case of the Pt54 diagram described above.

Capturing an infrared image of the target and transmitting a digital video signal
, a process of obtaining peak luminance data 6, luminance threshold data 8, and a lock-on signal 10, luminance threshold data 8,
The process of obtaining the guiding signal 14 from the digital video signal 4 is the same as that of the conventional device shown in FIG. 4, so the explanation will be omitted.

In Figure f51, the rIIIS measurement circuit 15 receives the digital video signal 4 and calculates the dispersion value (
r+as) is calculated for each screen and output as r III S data 16.

As shown in Fig. 2, the digital video signal 4 in one screen is B(i), the peak brightness data 6 is P1, the average brightness level of the digital video signal 4 is M, the number of samples for one screen is Z, and rms data. 16 and Nf respectively, Nr is expressed as follows.

The division circuit 17 receives the peak luminance data 6 and the rIos data 16, calculates the ratio thereof, and outputs the ratio as SN data 18. That is, the SN table 18 is expressed as follows.

5N=P/Nr On the other hand, the SN threshold value determination circuit 19 receives the peak luminance data 6, and depending on the value, as shown in the fjS3 diagram,
SN threshold data 2 which is the threshold of SN data 18
Determine 0. That is, as shown in FIG. The lock-on determination circuit 9 receives the SN data 18 and the SN threshold data 20, and if the SN data 18 is larger than the SN threshold data 20 at that time, it considers it to be a significant target peak and outputs the lock-on signal. Occur.

(Effects of the Invention) As described above, according to the present invention, the signal-to-noise ratio (SN) of the peak of a video signal is always measured, and this is used as the SN threshold determined depending on the magnitude of the peak brightness. By comparing with the value, it is determined whether the peak is caused by the target or sea surface noise. Therefore, when the target signal is small, lock-on will not occur unless the SN is high enough, and when the target signal is large, it can be set so that lock-on can be performed even with a relatively low SN, which can be a problem in faraway areas where the target signal is small. This can greatly contribute to reducing the probability of erroneous lock-on due to sea surface noise, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention;
Figure 12 is an explanatory diagram of the digital video signal, peak brightness data, and average brightness level, Figure 3 is an explanatory diagram of the dependence of the SN data threshold on the peak brightness, and Figure @4 is a conventional infrared missile guidance device. 1 is a block diagram showing an example of the configuration of FIG. DESCRIPTION OF SYMBOLS 1... Infrared imaging device, 2... Analog video signal, 3... A/D converter, 4... Digital video signal, 5... Peak detection circuit, 6... Peak luminance data, 7... Binarization threshold determination circuit, 8... Luminance threshold data, 9... Lock-on determination circuit, 10...
Lock-on (No. 5, 11...binarization circuit, 13...
Center of gravity calculation circuit, 14...guidance signal, 15...r I
II S measurement circuit, 16... ・ rtas data, 17... Division circuit, 18... SN data, 19
. . . SNt threshold value determination circuit, 20 . . . SN threshold value data.

Claims (1)

[Claims] (1) An imaging device that converts an image of the outside world into an analog video signal, an A/D converter that samples the analog video signal and outputs it as a digital video signal, and detects peak brightness from the digital video signal to obtain peak brightness data. a peak detection circuit that calculates a dispersion value of the digital video signal and outputs it as rms data;
a division circuit that calculates the ratio of the SN data to the SN data and outputs it as SN data;
a threshold determining circuit; a lock-on determining circuit that compares the SN data with the SN threshold data and outputs a lock-on signal according to the determination result; and a threshold for binarizing the peak luminance data. a binarization threshold determining circuit that determines and outputs the luminance threshold data as luminance threshold data; a binarization circuit that receives the lock-on signal and the luminance threshold data and binarizes the digital video signal; A guide device comprising: a center of gravity calculation circuit that calculates a center of gravity position of a target area from the binarized video data outputted by the binarization circuit and outputs the calculated center of gravity position as a guide signal.