JPS6146799A - Interference decision circuit for earth sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a determination circuit for determining interference of the sun or the moon with an earth sensor mounted on an artificial satellite or the like.

(Prior art) As shown in Fig. 4, this type of conventional circuit converts an analog signal output from a selected earth sensor into a digital signal using an interference detector having an appropriate threshold level, and converts the digital signal into a digital signal. Interference by the sun or the moon was determined by processing in an interference determination circuit. The principle of operation is as shown in Figure 5, when the sun or moon enters the field of view of the selected earth sensor, the output of the interference detector is the pulse produced by the interfering object and the normal pulse produced by the earth. This method takes advantage of the fact that pulses are generated.

(Problem to be Solved by the Invention) However, as shown in Figure 5, when the earth and the sun or the earth and the moon interfere when viewed from an artificial satellite, etc., the earth sensor created by the sun or the moon Because the output waveform and the earth sensor output waveform produced by the earth overlap, the interference detector cannot separate the two signals, resulting in incorrect interference judgments.

In order to eliminate these drawbacks, the present invention uses an interference sensor that has the same field of view as the earth sensor and is capable of detecting only the sun and moon. This makes it possible to determine interference even in a state where they are in contact.

(Means for Solving the Problems) A feature of the present invention for achieving the above object is that it has two earth sensors, and selects and outputs one earth sensor that is free from interference from the sun and the moon. In the earth sensor interference determination circuit,
two interferometric sensors having the same field of view as the corresponding earth sensor and detecting only the sun or the moon on the basis of energy or spectral characteristics; and conjunction means for providing a logical product of their outputs and the output of the earth sensor. The earth sensor interference determination circuit selects an earth sensor with no interference according to the output of the AND means and extracts the output thereof.

(Operation) Since an earth sensor without interference is selected according to the above-described configuration, the earth can be correctly identified even when the earth is in contact with the sun or the moon.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which ■ and 2 are earth sensors, 3 and 4 have the same field of view as l and 2, respectively,
An interference sensor that detects only the sun and the moon, 5 and 6 are amplifiers that amplify the output signals of the selected earth sensor and interference sensor to an appropriate level, and 7 is a sensor that detects the earth or the sun among the analog signals amplified by the amplifier 5. A leading edge signal detector 8 detects a trailing edge signal generated by the earth at an appropriate threshold level, 8 is a trailing edge signal detector 8 detects a trailing edge signal generated by the earth, and 9 is a trailing edge signal detector 9 that detects a trailing edge signal generated by the earth. An interference detector that detects leading edge signals generated by satellites, etc. at a threshold level slightly lower than 7, and IO is an interference detector that detects interference when two or more output pulses of 9 occur during one rotation of an artificial satellite, etc. A determination circuit 11 is an interference detector that detects the analog signal amplified by the amplifier 6 at an appropriate threshold level, and 12 is an interference detector that takes the logical product of the output pulses of the interference detectors 9 and 11, respectively, and determines the state in contact with the earth. 13 is an OR circuit that ORs the output pulses of the interference determination circuit 10 and the AND circuit 12; 14 is an OR circuit that combines the output pulses of the OR circuit 13; Registers 15 and 16 output a relay drive pulse at the time when a trailing edge pulse stored in a register etc. is input, and 15 and 16 are relay drive circuits that simultaneously drive two relays in the same direction with the output pulse of register 14. . In this embodiment, a circuit for determining solar or lunar interference is added to the conventional interference determination circuit shown in FIG. 4 based on an interference signal output by an interference sensor having the same field of view as the earth sensor. This structure makes it possible to determine the interference of the sun or moon while in contact with the earth, which was previously impossible. FIG. 2 is a diagram showing the operation of this embodiment, showing that interference determination is possible even when the sun or moon is in contact with the earth. As shown in the drawings, since the output waveform of the earth sensor from the sun or the moon is superimposed on the output waveform from the earth, no interference judgment pulse is output as the output of the conventional interference judgment circuit 10, but the logic added in this embodiment An interference determination pulse is output from the product circuit 12, and interference determination becomes possible. Furthermore, this interference determination pulse can be applied to simultaneously switch the earth sensor and the interference sensor via the OR circuit 13 and the register 14.

Note that as the interference detector, it is possible to use a conventional comparator that generates an output when the input level exceeds a predetermined threshold level. Further, the threshold level may be, for example, about 50% of the peak level. Further, the structure of the interference sensor may be the same as that of the earth sensor, except that an optical filter for identifying only the sun or the moon is used in the light input section.

(Effects of the Invention) As explained above, in the conventional earth sensor interference determination circuit, it is difficult to determine interference when the sun or moon is in contact with the earth. By applying this, it is possible to determine interference even in such cases.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing the operation of the embodiment of the present invention, showing that it is possible to determine the interference of the sun or the moon even when it is in contact with the earth. Figure 3 is a block diagram of a conventional earth sensor interference determination circuit, and Figure 4 is a diagram illustrating the operation of a conventional earth sensor interference determination circuit, showing that it is possible to determine interference from the sun or the moon when the earth is not in contact with the earth. , FIG. 5 is a diagram showing the operation of a conventional earth sensor interference determination circuit showing that it is impossible to determine interference with the sun or the moon when the earth is in contact with the earth. 1.2; Earth sensor, 3, 4; Interference sensor, 9,
10.11; Interference detector; 12; AND circuit; 13: OR circuit. Patent Application Person Nippon Telegraph and Telephone Public Corporation Patent Application Agent Patent Attorney Megumi Yamamoto - Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an earth sensor interference determination circuit that has two earth sensors and selects and outputs one earth sensor that is free from interference from the sun and the moon, the field of view is the same as that of the corresponding earth sensor and the energy or spectrum characteristics are the same. Basically, it has two interference sensors that detect only the sun or the moon, and a logical product means that provides a logical product of their output and the output of the earth sensor,
An earth sensor interference determination circuit characterized in that an earth sensor having no interference is selected according to the output of the AND means and the output thereof is taken out.