JPS6138078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horizon detection device mounted on an artificial satellite, a rocket, etc., and more specifically to a horizon detection device using a signal processing method that is not affected by the sun.

As a device for detecting the attitude of artificial satellites, rockets, etc., an infrared detector detects the temperature difference between space, which has a temperature of approximately 4K, and the earth, which has a temperature of approximately 230K, and detects the edge of the earth (horizon).
There is a horizon detection device that can detect the There are two ways to do this: one uses the spin of an artificial satellite or rocket to scan the universe and the earth, and the other uses a reflective mirror or prism to rotate the field of view.

FIG. 1 is a system diagram of a conventional horizon detection device, and FIG. 2 is a time chart showing waveforms of various parts.
A conventional horizon detection device will be explained using FIGS. 1 and 2.

Infrared energy 210 is incident on the infrared detector 11 by scanning space and the earth.
211 of this infrared energy 210 is space, 2
12 is the earth, and 213 is infrared energy radiated from the sun. Because the sun has a high temperature of approximately 6000K, it emits infrared energy (wavelengths 14 to 16
μm) is several tens of times larger than that of Earth. Also, the viewing angle of the Sun from the Earth is small, about 0.5 degrees. The incident infrared energy 210 is converted into an electric signal by the infrared detector 11, and is amplified and waveform-shaped by the amplifier 12 including a band-limiting circuit having a differentiation function to become a signal 220. Signal 220 from amplifier 12 enters earth rise signal generator 13 and earth fall signal generator 14. The earth rising signal generator 13 compares the signal 220 with a rising comparison voltage 221 to generate an earth rising signal 230. Similarly, earth fall signal generator 14 compares signal 220 with fall comparison voltage 222 to generate earth fall signal 240. Earth width signal generator 1
5, it is set with the earth rising signal 230, reset with the earth falling signal 240, and the earth width signal 25 is set.
Generates 0. In the global signal 250, 25
1 is a normal earth width signal that is not affected by the sun, 2
Reference numeral 52 indicates an abnormal signal whose width becomes wider, extending from the time when radiation from the sun enters the infrared detector 11 to the time when the radiation changes from the earth to the space. If the sun were not present, the signal 252 would be a normal signal, with only the signal 253 in the shaded area. This width signal 250 is sent to a counter 16 which counts pulses from another clock generator 18 while the width signal 250 is rising. The number of pulses counted by the counter 16 is input in parallel to the shift register 17 as a binary output at the same time as the counter 16 finishes counting. This is read out in chronological order and transmitted to the ground.
Therefore, when the sun comes into the field of view, the abnormal signal 252 is transmitted as is, as described above, causing problems in determining the attitude of the artificial satellite, etc.

The present invention attempts to eliminate such inconveniences. An example of this will be described below. FIG. 3 is a system diagram of a horizon detection device according to an embodiment of the present invention, and FIG. 4 is a time chart showing waveforms of various parts. Incident infrared energy 410
is converted into an electrical signal by an infrared detector 31, and amplified and waveform-shaped by an AC amplifier 32 having a differential function including a band limiting circuit having a differential function, resulting in a signal 420. Signal 420 from AC amplifier 32
enters an earth rise signal generator 33, an earth fall signal generator 34, and a sun removal signal generator 35. In the earth rising signal generator 33, the signal 420
The earth rising signal 43 is compared with the rising comparison voltage 421 which is larger than 0 and smaller than the earth signal maximum value.
Generates 0. Similarly, earth falling signal generator 3
4, the signal 420 is compared with a falling comparison voltage 422 to obtain an earth falling signal 450, and in the sun removal signal generator 35, the signal 420 is compared with a falling comparison voltage 422 which is greater than the maximum value of the earth signal and smaller than the solar signal.
3, it generates a sun removal signal 460 that rises at the same time and falls after a time t ₁ that is longer than the time that the sun signal exists. When this sun removal signal 460 is generated, this signal reduces the amplification degree of the AC amplifier 32 to a fraction of a factor to zero, thereby avoiding unnecessary saturation of the amplifier, and reducing the output signal 42 of the amplifier 32.
Of the signal 424 caused by the sun at 0, the shaded part 425
is made to be less than or equal to the rising comparison voltage 421.
In this way, the shaded portion 432 of the sun signal 431 of the earth rise signal 430, which is the output of the earth rise signal generator 33, is not output. In the solar delay signal generator 36, the solar removal signal 460
The rise of t generates a single pulse solar delay signal 470 that rises after _t2 hours. However, O<t ₂ <
Let t be ₁ . The earth width signal generator 37 generates an earth width signal 490 that is set at the rising edge of the earth rising signal 430 and reset at the reset pulse 480 of either the earth falling signal 450 or the sun delay signal 470. Counter 38 counts pulses from another clock generator 40 while the span signal 490 is rising to time the span signal 490 . The number of pulses measured by the counter 38 is input in parallel to the shift register 39 as a binary output consisting of a plurality of outputs corresponding to the number of stages of the counter 38 at the same time as the counter 38 finishes counting, that is, at the falling edge of the earth width signal 490. be done. In this case, if the sun is not in the field of view of the infrared detector, the same signal as before is obtained, but if the sun is in the field of view, the signal 491 due to the sun of the earth width signal 490 exists, and the counter 38 counts. , but is reset at the rising edge of the sun removal signal 460. That is, the contents of the counter 38 become zero. Therefore, since the contents of the counter 38 at the time of falling of the signal 491 caused by the sun, which is the input time to the shift register 39, are all zero, zero is input to the shift register 39, and as a result, the influence of the signal 491 caused by the sun is I don't receive it. When the output of this register 39 is read out in chronological order, an earth width measurement signal 495 is obtained. In other words, even if the sun enters the field of view of the infrared detector, the sun cannot be measured for a period of time t ₁ , which is approximately the sum of the field of view of the sun (approximately 0.5 degrees) and the field of view of the infrared detector (approximately 1 degree). It becomes a normal earth width signal 495 without being affected by this.

As described above, the present invention uses a horizon detection device that detects the temperature difference between space and the earth to determine the attitude of an artificial satellite, etc. In order to eliminate the resulting false earth signal, apart from the rising and falling comparison voltages for detecting the earth signal,
A third comparison voltage that is larger than the maximum value of the signal from the earth and smaller than the signal from the hot celestial object is used to create a hot celestial object signal, and this hot celestial object signal lowers the amplification of the amplifier to avoid unnecessary saturation of the amplifier. This horizon detection device resets the counter that measures the earth's width while this high-temperature celestial body signal is present, and the edge of the earth is reliably detected without being affected by high-temperature celestial bodies such as the sun. It is possible to determine the posture such as

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing signal processing etc. of a conventional horizon detection device, Fig. 2 is a waveform diagram of the main part of Fig. 1,
FIG. 3 is a block diagram showing the signal processing system of the horizon detection device according to the present invention, and FIG. 4 is a waveform diagram of the main part of FIG. 3. 31...Infrared detector, 32...Amplifier, 33
...Earth rise signal generator, 34...Earth fall signal generator, 35...Sun removal signal generator, 36
... Solar delay signal generator, 37 ... Earth width generator, 38 ... Counter, 39 ... Shift register, 40 ... Clock generator, 410 ... Incident infrared rays, 420 ... Amplification, waveform shaping signal, 4
21... Comparison voltage greater than 0 and smaller than the earth signal maximum value (positive earth comparison voltage), 422... Negative comparison voltage, 423... Solar comparison voltage, 424...
...Signal from the sun, 425...Signal from the sun 4
Among 24, the signal after becoming larger than the positive earth comparison voltage, 430...Earth rising signal, 431
...Signal from the sun, 432... Part common with 425 of the signal from the sun 431, 450... Earth fall signal, 460... Sun removal signal, 470
...Solar delay signal, 480...Reset pulse,
490...Earthwidth signal, 491...Signal due to the sun, 492...Part common with the sun removed signal 460 in signal 491 due to the sun, 495...Normal earthwidth signal.

Claims (1)

[Claims] 1. An infrared detector that converts infrared rays incident from the earth and outer space into electrical signals, an AC amplifier that has a differential function that amplifies the electrical signals, and detects the rise and fall of the signal from the earth from the output of the AC amplifier. an earth rise signal generator and an earth fall signal generator, and a time width longer than the duration of the sun signal based on a reference value that is greater than the maximum value of the earth signal and smaller than the sun signal from the output of the AC amplifier; A sun removal signal generator that generates a sun removal signal of an earth-width signal generator that is reset by the output of a solar-delayed signal generator that generates pulses delayed by a time; and a counter that counts clock pulses based on the output of the earth-width signal generator and is reset by a sun removal signal. A horizon detection device comprising: reducing the amplification degree of the AC amplifier by the sun removal signal.