JPS6357742B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a missile homing device, and more particularly to a switching device for error angle versus error output characteristics.

Generally, a missile homing device is constructed as shown in FIG. That is, the incident infrared light obtained from the eye is transmitted to the rotary reticle 1 of the FM system by an optical system 11 mounted on a gyro.
2 and is FM modulated. The pattern of this reticle 12 is formed so that the modulation index of FM modulation differs in the radial direction, and a direction serving as a reference for change in the modulation index is determined in the circumferential direction.
Infrared light passing through this reticle 12 is sent to an infrared detector 1.
3 is converted into an electrical signal, and this electrical signal is
By demodulating it with the FM demodulator 14, an amplitude corresponding to the modulation index is obtained, and this signal is detected by the phase detector 15 with reference to the reference pulse that is guided every time the rotational position of the reticle 12 reaches the reference direction. By performing phase detection, an output corresponding to the position in the circumferential direction is obtained. By processing the output thus obtained by the target identification circuit 16, the position of the target image on the reticle 12 in terms of polar coordinates is identified. Then, based on the target identification signal obtained in this way, the steering control of the aircraft and the drive control of the gyro 18 are performed via the servo amplifier 17, and the target is captured in the center of the field of view of the optical system 11. Homing is performed in the direction.

By the way, in the homing device as described above, the characteristics of the FM demodulation output, that is, the error voltage, with respect to the angle that the optical system 11 and the reticle 12 are oriented to with respect to the line LOS connecting the aircraft and the target, that is, the error angle, are shown in Figure 2. As shown, the error angle and the error voltage do not have a linear relationship, and the change in the error voltage with respect to the change in the error angle is larger at the center A where tracking is performed than at the ends B. Therefore, when a target is captured at the edge of the field of view, the optical system 11 is driven so as to capture the target at the center A of the field of view, so that the target is tracked at the center A.

However, according to these characteristics, when a true target enters the field of view first and then a pseudo target such as a flare, the error voltage for the pseudo target is much larger than the error voltage for the true target. Sometimes there is a risk of tracking a false target by mistake, and if there is IR interference, tracking may become impossible.

The present invention was made in view of the above circumstances, and
The FM demodulator uses the FMFB (Frequency Negative Feedback FM) method, and a wideband VCO (voltage controlled oscillator) is used until the first target in the field of view is captured and tracked at the center of the field of view, and then a narrowband VCO is used. By switching and using the homing device, it is possible to track the true target that is initially captured.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In Fig. 3, 12 is a rotating reticle mounted on a gyro together with the optical system 11, and is an FM
This is an FM reticle with a modulation pattern.
13 is an infrared detector that converts the FM modulated infrared light that has passed through the reticle 12 into an electrical signal. A frequency converter 20 converts the frequency of the output signal of the detector 13 by mixing it with an output signal of a wideband VCO 21 or a narrowband VCO 22, which will be described later. Reference numeral 23 denotes a narrowband bandpass waveformer for extracting a predetermined conversion frequency output signal of the converter 20. Reference numeral 15 denotes a phase detector which performs phase detection between the output signal of the wave detector 23 and a reference signal detected each time the rotational position of the reticle 12 faces the reference direction. Reference numeral 16 denotes a target identification circuit for identifying the target position from the output signal of the detector 15, and the identification output is used to control the steering of the aircraft and the drive of the gyro 18 via the servo amplifier 17.

On the other hand, 24 is a switching relay contact, which connects the output of the wave converter 23 to the wideband VCO 21 or the narrowband VCO 21.
This is for switching and supplying the control input to the VCO 22. and 25 is the target identification circuit 16
26 is a delay circuit that delays the output signal of the delay circuit 25 for a predetermined period of time, and 26 is a relay coil that switches and drives the relay contact 24 based on the output of the delay circuit 25. Note that the loop of the frequency converter 20, wave generator 23, switching relay contact 24, and VCO 21 or 22 forms an FM demodulator 27 of the FMFB type.

Next, the operation of the homing device will be explained with reference to FIG.

Normally (before target acquisition), the relay contact 24 selects the broadband VCO 21 side. In this state, when the target is captured just at the edge of the viewing angle,
Detector 1 that responds to infrared light that has passed through reticle 12
Although the frequency deviation of the FM signal output in 3 is large, FMFB
FM demodulation is possible by the method demodulator 27, and tracking is performed such that the target is captured at the center of the field of view under control based on the target identification output at this time.
The error angle versus error voltage characteristic in this case is similar to the conventional characteristic shown in FIG. 2, as shown in FIG. 4a,
If the field of view moving speed of the optical system 11 and reticle 12 is, for example, 10°/sec, then the error voltage characteristic will move from the edge of the field of view to the center A where the slope is steep.
It takes about 0.3 seconds to move through a viewing angle of up to 3 degrees (for example, 3 degrees). Therefore, the target identification signal is processed by the delay circuit 25.
The delay signal is delayed by 0.3 seconds, and the relay contact 24 is controlled to switch based on this delayed signal. Therefore, the switching to use the narrow band VCO 22 is performed after the target is captured at the center A. be exposed. In this case, wideband VCO21 and narrowband VCO
For example, the frequency ratio with respect to 22 is selected to be 10:1. After switching to the narrowband VCO 22 in this way, even if a large infrared light source (usually a pseudo target such as a flare that enters the field of view after tracking the real target) enters the field of view edge B, , the frequency shift of the output signal of the infrared detector 13 corresponding to this is large, so the frequency conversion output of this signal is output by the wave detector 23.
Therefore, it is impossible to extract. Therefore, the difference angle vs. error voltage characteristic in this case is as shown in Figure 4b, where the error voltage increases in proportion to the error angle near the center of the visual field A, but the error angle changes at the edge of the visual field B. However, the error voltage remains zero. Therefore, the pseudo target that enters the edge B of the visual field is ignored, and target tracking is performed only in the center A of the visual field.

Assuming that there is a missile and a target that have a proportional rudder method, j = Nφ〓 …(1) where j: rate of change in path angle N: proportional rudder constant φ: rate of change in LOS φ〓=Kε … (2) where K: constant (loop gain) ε: error voltage with respect to viewing angle Vj = A...(3) where V: missile speed A: horizontal turning performance is established. Here, V=1000m/sec, A=20G
Then, from equation (3), j=A/V=20×10/1000=0.2rad/sec=11.46°/se
c ...(4), and if N = 5, then from equations (1) and (4), φ = j / N = 11.46 / 5 = 2.29 ° / sec, and if K = 10 ° / sec, then (2 ), from equation (5), ε=φ〓/K=0.229°/sec...(6). Therefore, if the viewing angle is 6 degrees, the tracking range should be 4% of the diameter and 8% of the radius of the viewing area, and in this example, the viewing angle at center A in Figure 4 is 10% of the total viewing angle. That's enough. Therefore, in this case, while tracking the true target at the center of the field of view A, the probability that a pseudo target will enter the center of the field of view A is 1/100 if the pseudo targets are uniformly distributed. ,IR
Even with interference, the probability is extremely low.

As described above, according to the homing device of the present invention, the FM demodulator is of the FMFB type, and a switching circuit for selecting a wideband VCO or a narrowband VCO is inserted in the loop, and the wideband VCO is selected initially. When the target identification output is obtained, the optical system is oriented to track the target at the center of the field of view, and then the narrowband VCO is selected.
Due to the error angle vs. error voltage characteristics when using a wideband VCO, only the above-mentioned target is tracked and targets (usually pseudo-targets) that enter the field of view after this target are ignored. Therefore, homing can be performed that is extremely strong against R interference.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing a conventional homing device, FIG. 2 is a diagram showing viewing angle versus error voltage characteristics in the device of FIG. 1, and FIG. 3 is a diagram showing an embodiment of the homing device according to the present invention. The configuration explanatory diagrams, FIGS. 4a and 4b, are diagrams showing the characteristics when wideband VCO or narrowband VCO is selected in the apparatus of FIG. 3. 11...Optical system, 12...FM reticle, 1
5... Phase detector, 16... Target identification circuit, 17
... Servo amplifier, 18 ... Gyroscope, 20 ...
Frequency converter, 21... Wideband VCO, 22...
Narrowband VCO, 23...bandpass waver, 24...
Switching relay contact, 26...Relay coil, 27...
...FMFB method FM demodulator.

Claims (1)

[Claims] 1. The infrared incident light is focused onto the FM reticle by an optical system, the infrared light that has passed through this reticle is converted into an electrical signal, and the above FM demodulated output is converted using the reference signal representing the rotational reference position of the reticle as a reference. In a homing device that performs phase detection, identifies a target based on the detection output, and performs target tracking of the aircraft, the optical system, and the reticle according to the identification results, an FM FB type FM demodulator is used, and the As a voltage controlled oscillator, a wide band is used until the first target is captured and tracked at the center of the field of view of the optical system, and the narrow band is switched to use a narrow band during tracking at the center of the field of view. A homing device featuring: