JPS6261900A - Noise removing 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 (Industrial Application Field) This invention relates to a signal processing device for an earth sensor mounted on an artificial satellite, in particular, a noise signal mixed in the output signal of the earth sensor is used as a reference signal for the control system of the artificial satellite. It is related to the function of preventing the control system from malfunctioning by preventing it from being used incorrectly as a control system.

(Prior Art) Fig. 6 shows an example of a conventional circuit of this kind, in which 1 is an earth sensor, 2 is a voltage comparator for leading edge pulse detection which inputs the output signal of the earth sensor 1, and 3 is an earth sensor. A voltage comparator for detecting trailing edge pulses receives the output signal 1, and a timer 4 generates a gate control signal for a certain period of time from the rising or falling edge of the leading edge pulse generated by voltage comparator 2 for detecting leading edge pulses. The circuit 5 is a gate circuit 21 that prohibits passage of the trailing edge pulse outputted by the trailing edge pulse detection voltage comparator 3 only during the period when the gate control signal outputted by the timer circuit 4 is at a high level.
is the output signal line of the earth sensor 1, 22 is the output signal line of the leading edge pulse detection voltage comparator 2, 23 is the output signal line of the trailing edge pulse detection voltage comparator 3, and 24 is the output signal of the timer circuit 4. Line 25 is an output signal line of the gate circuit 5.

Conventional circuits of this type are configured as described above, and the trailing edge signals generated by these celestial bodies, which are mainly generated when the earth sensor scans the earth for a month or the sun, are mistakenly used as reference signals for control systems of artificial satellites, etc. It was designed to prevent this from happening. Below, the voltage waveforms generated in each of the signal lines 21, 22, 23, and 24. The scanning cases are shown in FIGS. 7 and 8, respectively.

7 and 8, 41 indicates the earth as seen from the satellite, 42 indicates the scanning direction of the earth sensor 1, and 43 indicates the moon or the sun. In FIGS. 7 and 8, 51 indicates the earth sensor 1.
When the earth sensor 1 scans the earth, a positive leading edge signal and a trailing edge signal are generated at the earth's leading edge and negative at the earth's trailing edge, respectively. . Further, in FIG. 8, it is assumed that leading edge signals and trailing edge signals from the moon or the sun are superimposed on the signal line 21. In FIGS. 7 and 8, 52 is a leading edge pulse waveform generated on the output signal line 22 of the leading edge pulse detection voltage comparator 2, and the reference voltage A (
A pulse corresponding to V) appears. In FIGS. 7 and 8, 53 is a trailing edge pulse generated on the output signal line 23 of the voltage comparator 3 for trailing edge pulse detection, and corresponds to the reference voltage -B (V) set in the voltage comparator. A pulse appears. In FIGS. 7 and 8, 54 is a gate control signal generated on the output signal line 24 of the timer circuit 4, and the gate control signal appears for a certain period of time from the rise of the leading edge pulse waveform 52. The time width of this gate control signal 54 is slightly larger than the time difference between the rises of the leading edge signal and the trailing edge signal generated when the earth sensor scans the moon or the sun, and the time difference between the leading edge signal and the trailing edge signal of the earth. It is set smaller than the rise time difference. In FIGS. 7 and 8, 55 is a signal waveform generated on the output signal line 25 of the gate circuit 5. In FIG. In FIG. 8, trailing pulses due to the moon or the sun are inhibited by gate control signal 54 and therefore do not appear on output signal line 25.

As explained above, in the conventional circuit of this type, the time width of the gate control signal is set to be slightly larger than the time difference between the leading edge signal and the trailing edge signal due to the moon or the sun, thereby controlling the trailing edge signal due to the moon or the sun. By prohibiting the pulse from passing through the gate circuit 5, it was possible to remove interference from the moon and the sun.

(Problems to be Solved by the Invention) However, in the conventional circuit, if an erroneous trailing edge pulse is generated beyond the time width of the gate control signal due to noise mixed in the output signal line 21 of the earth sensor 1, If an erroneous leading edge pulse is generated due to similar noise, this cannot be prevented, and the erroneous signal is input to the control system, resulting in malfunction.

The purpose of the present invention is to prevent the generation of erroneous signals by noise with positive and negative polarities mixed in the output signal of an earth sensor, and to control the control system by using the erroneous signal as a reference signal for the control system of an artificial satellite. An object of the present invention is to provide an earth sensor noise removal circuit that prevents the system from malfunctioning.

(Means for Solving the Problems) A feature of the present invention for achieving the above-mentioned object is that the present invention is mounted on a spin satellite or the like, and when scanning the earth by utilizing the rotation of the spin satellite. an earth sensor for generating a leading edge signal and a trailing edge signal at the trailing edge, respectively; means for generating a leading edge pulse or a trailing edge pulse from the leading edge signal and the trailing edge signal; At least one of them is provided with a phase synchronization circuit that inputs one signal, generates a signal synchronized with the rotation of the spin satellite, and adjusts the phase of the synchronization signal, and each of the two of the above-mentioned surface edge pulse and trailing edge pulse. The earth sensor noise removal circuit removes noise of any phase and any polarity mixed in the output signal of the earth sensor by generating a signal phase-synchronized with the pulse.

(Operation) The present invention uses at least one of the leading edge pulse and the trailing edge pulse generated by the earth, and performs processing such as frequency division on the output of a voltage controlled oscillator controlled to be synchronized with the rotation of the spin satellite. By applying this, two pulses with the same phase as the leading edge pulse and the trailing edge pulse from the earth are generated, and the erroneous leading edge due to noise sporadically mixed into the output signal of the earth sensor due to the wheel effect of the voltage controlled oscillator is generated. The leading edge pulse and the trailing edge pulse are removed. Conventional techniques aim to eliminate only false trailing pulses caused by the moon or the sun. This is prohibited by inputting it to a gate circuit that is controlled by a gate control signal that continues for a certain period of time from the rising edge, and the method is completely different from that of the present invention.

(Example 1) FIG. 1 is a diagram illustrating a first example of the present invention,
1 to 3 and 21 to 23 are completely the same as the conventional circuits described above. 6 and 7 are monostable circuits whose output signals are at high level for approximately 1/2 of the satellite's rotation period from the rising edge of the leading edge pulse and trailing edge pulse, respectively, and 26.27 are the output signals of 6 and 7, respectively. It is a line. 8, 9, 10
．． 11 constitutes a phase locked loop, 8 a phase comparator that detects the phase difference between the output signal of 6 and the output signal of 11;
9 is a loop filter that inputs the output signal of the phase comparator 8; IO is a voltage-controlled oscillator that controls the oscillation frequency by the output voltage of the loop filter 9; 11 is a voltage-controlled oscillator 10
This is a frequency divider that divides the output signal of . 28, 29, 30
．． 31 are output signal lines of 8, 9, 10, and 11, respectively.

12.13.14 constitutes a phase control loop, and 1
2 is a phase comparator that detects the phase difference between the output signal of 7 and the output signal of 14, and 13 is a frequency divider that divides the frequency only when the output signal of phase comparator 12 is within a certain value range. This is a phase controller that controls the timing of starting division of the oscillation frequency of the voltage controlled oscillator IO. 32.degree.33.34 are 12, 13.14 output signal lines, respectively. 15
and 16 are monostable circuits that generate output signals for a time approximately equal to the duration of the leading edge pulse and trailing edge pulse of the earth, respectively, from the rising edge of the output signals of the frequency dividers 11 and 14.

35 and 36 are output signal lines of monostable circuits 15 and 16, respectively. As an example of the operation of the circuit in FIG.
Output signal line 21゜22.23,26,31,2 in the figure
The voltage waveforms generated at 9, 27, 34, 32, 35. Figure 2, shown in Figures 2, 3 and 4 for three cases, respectively.

In FIGS. 3 and 4, 51, 52, and 53 are the same as the voltage waveforms with the same numbers shown in FIGS. 7 and 8.

56, 57, 58,
59°60.61, 62.63 are the output signal lines 26, 31, 29, 27, 34, 32 . . . shown in FIG. 1, respectively.
This is the voltage waveform generated at 35 and 36. In Figure 2, there is no noise in the output signal of the earth sensor, so 8,
9.10.11 Output signal 57 of the phase-locked loop consisting of
coincides with the phase of the output signal 56 of the monostable circuit 6, the output signal of the phase comparator 8 becomes zero, and the output signal 62 of the monostable circuit 15 has the same phase as the leading edge pulse 52 caused by the earth. A signal with a phase of 1 and approximately the same pulse width is obtained. Similarly, since the phase of the output signal 60 of the phase control loop consisting of 12, 13, and 14 also matches the phase of the output signal 59 of the monostable circuit 7, the output signal of the phase comparator 12 becomes zero, and Output signal 63 of monostable circuit 16
, a signal having the same phase and approximately the same pulse width as the trailing edge pulse 53 due to the earth is obtained. FIG. 3 is a diagram showing the operation when negative noise is mixed into the output signal 51 of the earth sensor 1, and a pulse-like phase error signal is generated in the output of the phase comparator 12 due to the negative noise. Phase controller 13
is designed to detect the pulse width of this error signal, and if this width is larger than a predetermined value, reject this error signal, and if the phase error is larger than a predetermined value, the frequency divider 14 The phase of the output pulse of will be equal to the phase of the one previous pulse, so that at the output of the monostable circuit 16 there will be a signal of the correct phase, which is the same as the phase of the trailing edge pulse due to the earth. However, even in this case, a slight effect of phase error remains, and if the pulse width of the error signal is smaller than a predetermined value, the frequency divider will be controlled incorrectly as a normal signal, so it should be a dotted line. The output of line 16 will be slightly shifted as shown by the solid line. Figure 4 shows earth sensor 1
2 is a diagram showing the operation of the circuit of FIG. 1 when positive noise is mixed into the output signal 51 of FIG. In this case, a phase error occurs in the output of the phase comparator 18 due to positive noise, but if the band of the filter 9 is made small, this phase error is smoothed and the amplitude becomes small, and the output of the voltage controlled oscillator 10 is The impact can be minimized. Therefore, the output signal 6 of the monostable circuit 15
As shown in the figure, the phase of No. 2, which should be a dotted line, only changes slightly as shown in a solid line, and a correct signal with almost the same phase as the leading edge pulse of the earth can be obtained.

(Example 2) FIG. 5 is a diagram illustrating a second example of the present invention,
The difference from the first embodiment is 12.13.1 in Figure 1.
8゜9.10.1 of Fig. 1.
The only difference is that the phase-locked loop consisting of 1 is replaced with phase-locked loops 12.17 and 18.19 having the same configuration, and the operation of the circuit is the same as in Embodiment 1. For example, even if noise of any phase and polarity is mixed into the output signal of the earth sensor, it is possible to prevent the generation of erroneous signals due to such noise and obtain a correct signal with the same phase as the leading edge pulse and trailing edge pulse from the earth. I can do it.

(Effects of the Invention) As explained above, since it is possible to prevent the generation of erroneous signals due to noise mixed in the output signal of the earth sensor, the present invention can prevent the leading edge signal generated when the earth sensor scans the earth. When the trailing edge signal is used as a reference signal for a control system of an artificial satellite, it is effective in preventing malfunctions of the control system caused by an erroneous reference signal due to noise.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention, FIG.
3 and 4 are diagrams showing voltage waveforms of each signal line in the configuration diagram shown in FIG. 1, FIG. 5 is a diagram showing a second embodiment of the present invention, and FIG. 6 is a diagram showing a conventional earth sensor. FIGS. 7 and 8 are block diagrams showing the noise removal circuit, and are diagrams showing voltage waveforms of each signal line in the block diagram shown in FIG. 6. In the figure, 1 is an earth sensor, 2 is a voltage comparator for detecting leading edge pulses, 3 is a voltage comparator for detecting trailing edge pulses, 6 and 7
are monostable circuits that are triggered by the rising edge of the leading edge pulse and the trailing edge pulse, respectively; 8 and 9°; 10.11 are the phase comparator, filter, voltage-controlled oscillator, and frequency divider, respectively, which constitute a phase-locked loop; 12° 13. 14 are phase comparators 9 phase controllers and frequency dividers, respectively, which constitute a phase control loop, 15 and 16 are triggered by the outputs of frequency dividers 11 and 14, and are equal to the pulse width of the leading edge pulse and the trailing edge pulse. This is a monostable circuit that outputs a pulse with a time width of .

Claims (1)

[Claims] An earth sensor that is mounted on a spin satellite or the like and generates a leading edge signal and a trailing edge signal at the leading edge and trailing edge of the earth, respectively, when scanning the earth using the rotation of the spinning satellite. and means for generating a leading edge pulse or a trailing edge pulse from the leading edge signal and the trailing edge signal, and inputting at least one of the leading edge pulse and the trailing edge pulse to synchronize with the rotation of the spinning satellite. and a phase synchronization circuit that generates a signal and adjusts the phase of the synchronization signal, and generates a signal that is phase synchronized with the two pulses, the leading edge pulse and the trailing edge pulse, respectively, thereby adjusting the output signal of the earth sensor. An earth sensor noise removal circuit characterized in that it removes noise of any phase and any polarity mixed into the earth sensor.