JP2520871B2 - Antenna pointing direction detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is directed to an antenna based on a beacon signal from a ground station which is used to direct an antenna mounted on an artificial satellite in a desired direction on the ground with high accuracy. The present invention relates to an antenna pointing direction error detection device that detects an error.

[Conventional technology and problems]

Conventionally, this type of device has been constructed by providing one ground station and one system of a power feeding horn and a power feeding circuit for detecting a pointing error of a satellite-mounted antenna facing the ground station.

However, at frequencies higher than the microwave band, the pointing error detection signal (beacon signal) may be attenuated due to rainfall or the like, and the beacon line may be disconnected.In such a case, the antenna pointing error increases. However, there is a problem that the operating rate of the entire satellite deteriorates.

On the other hand, as a similar structure, two ground stations are provided, and two pointing direction detection systems mounted on the satellite are provided in "Japanese Patent Application Laid-Open No. 55-74221" and "Japanese Patent Application No. 59-197793".
Etc. are disclosed in.

The characteristic structure of this case is shown in FIG.

In FIG. 1, 1 is the earth, 2a and 2b are ground stations, 3 is a satellite antenna mirror surface, 4a and 4b are feeding horns and feeding circuits, 5a and 5b are tracking receivers, and 6a and 6b are antenna pointing error output signals. , 7 is a yaw angle calculation circuit, 8 is a yaw angle signal,
The configuration shown in this figure is used to obtain the rotation angle of the yaw axis of the satellite from the directions of two ground stations. In such a configuration, when the antenna pointing direction control is performed using the output of the antenna pointing error detection system (for example, the antenna pointing error output signal 6a), which is composed of the antenna feeding circuit and the tracking receiver, this system is used. If the beacon signal line of is disconnected, the other antenna pointing error output 6b
It is possible to control the antenna pointing direction by using.

However, in the case of this configuration, if one of the tracking receivers fails, the satellite cannot be repaired after that, so that the deterioration of the communication line operating rate cannot be relieved. Therefore, in order to improve the reliability of the device, it is necessary to provide both tracking receivers with a redundant system, resulting in a problem that the weight of the entire device becomes significantly large.

[Object of the Invention]

An object of the present invention is to provide a directional detection device for a satellite-mounted antenna, which can improve the line availability while maintaining the reliability of the device and can be realized with a simple structure. There is.

[Means for solving problems]

According to the invention, the above object is achieved by means of the claims. That is, the present invention is based on the ground station n
Stations are installed, and each ground station transmits antenna pointing error detection signals (beacon signals) with different frequencies, and each antenna has a power supply circuit for antenna pointing error detection on the satellite corresponding to each ground station. The main feature is that the circuit outputs are combined and guided to a tracking receiver, and n signals are demultiplexed by a filter inside the tracking receiver so that signals from each ground can be processed. Comparing this with the conventional technology, in the conventional technology, since only one ground station is usually provided, in the case where the beacon line is disconnected, there is no remedy, and in order to compensate for this, the ground station and the antenna feed Even if n circuits are provided, in order to improve the reliability of the device in order to maintain the operating rate, the tracking receiver has to be duplicated to have a complicated structure, whereas the present invention does the tracking. Since it is not necessary to duplicate the receiver, it is different from the prior art in that it is possible to realize a system having a simple structure, light weight, high operating rate, and high reliability.

〔Example〕

FIG. 2 is a diagram for explaining one embodiment of the present invention,
The case where there are two ground stations is shown.

In FIG. 2, 1 is the earth, 2a and 2b are ground stations, 3 is a satellite antenna mirror surface, 4a and 4b are antenna directional error detection (but may also be used for communication) feed horns and feed circuits, 9 is a signal combining circuit, 5a and 5b are tracking receivers, 10
Is a frequency converter, 11a and 11b are filters, 12a and 12b are demodulators, and 6a and 6b are antenna pointing error output signals.

In the present embodiment, the pointing direction detection signals (frequency Fa, Fb) transmitted from the ground stations 2a, 2b are supplied to the tracking receiver 5a through the feeding circuits 4a, 4b and the signal synthesizing circuit 9, respectively. The two signals are frequency-converted by the frequency converter 10 in the tracking receiver 5a, and the frequencies become fa and fb.

The signal of frequency fa passes through the filter 11a and is demodulated by the demodulator 12a.
Is demodulated by and becomes the antenna pointing error output signal 6a for the ground station 2a.

Similarly, the signal of frequency fb passes through the filter 10b and the demodulator 12b and becomes the antenna pointing error output signal 6b for the ground station 2b.

Therefore, when the antenna pointing error output signal 6a is used to control the pointing direction of the antenna, the antenna pointing error output signal 6b for the ground station 2b can be obtained even if the signal from the ground station 2a is cut off due to rainfall or the like. As a result, the antenna pointing direction control can be performed. 2 like this
If the distance between the ground stations is more than a certain distance, the probability that both beacon lines will be cut off is very low, so
Higher mobility can be maintained.

When a so-called hybrid circuit is used as the signal combining circuit, two outputs are obtained, so one output is supplied to the tracking receiver 5a and the other output is supplied to the tracking receiver 5b. With this, without adding a special circuit such as a switching circuit, a redundant configuration in which the tracking receiver 5b of the standby system is added,
The reliability of the device can be improved.

For example, if the apparatus having the configuration shown in FIG. 1 which is one of the prior arts is configured to have 100% redundancy as in the example shown in FIG. 2, four frequency converters and four demodulators are required. However, in the example of FIG. 2, it can be seen that the frequency converter may have two systems and the configuration is simple. Further, in the configuration example of FIG. 2, although the demultiplexing is performed by the filter at the intermediate frequency, if this is performed in the high frequency section, four frequency converters are required. Since the part (for example, the power feeding circuit and the high frequency amplifier circuit) can be shared by two waves of different frequencies, the configuration is simple and the weight can be reduced.

In the antenna pointing direction detection by the monospar tracking method, in order to detect a two-dimensional pointing direction error (for example, north-south direction in east-west direction, or azimuth direction and elevation direction), one reference signal and two-dimensional Two error signals for the axes are input to the tracking receiver. Here, the reference signal is a tracking signal reception signal in which the amplitude is almost maximum when the antenna pointing direction and the tracking signal arrival direction match, and the phase is almost constant in the antenna pointing direction detectable angle range. Indicates that the amplitude becomes almost zero when the antenna pointing direction and the tracking signal arrival direction match, and the amplitude increases as the angle of deviation between the antenna pointing direction and the tracking signal arrival direction increases, and at the same time the antenna pointing direction and the tracking signal The received signal is a tracking signal whose phase is inverted depending on the direction of deviation of the antenna pointing direction around the angle at which the signal arrival directions coincide.

The method for obtaining these signals is described in, for example, the literature “Kenichi Miya,“ Satellite Communication Engineering ”published by Latteris, June 30, 1969, first.
There is a method using a plurality of primary radiators, that is, electromagnetic horns, and a method for detecting a higher-order mode, as shown in "Printing".

In the method using a plurality of horns, for example, four primary radiators are symmetrically arranged, beams are slightly shifted from each other with respect to the antenna axis, and a feeding circuit is configured to obtain the sum of each horn. , This output is used as a reference signal. Also,
For example, if the power supply circuit is configured to obtain the difference between the horn outputs arranged in the east and west, an error signal in the east-west direction is obtained, and if the feed circuit is configured to obtain the difference between the horn outputs arranged in the north and south. An error signal in the north-south direction is obtained.

In the higher-order mode detection method, when the antenna faces the tracking signal transmission source, the electromagnetic field mode induced in the primary radiator is only the fundamental mode, but when the antenna is misaligned, the higher-order mode is induced. It This basic mode is used as a reference signal and the higher order mode is used as an error signal.

Therefore, the feeding horn and the feeding horn in the feeding circuits 4a and 4b may each have one electromagnetic horn as in the high-order mode detection method, and in the multiple horn method, two in two dimensions and two in two dimensions. In some cases, if three or more horns are used, a two-dimensional error can be theoretically detected.

Here, as the reference signal, the sum of all horn outputs is used when four horns are used, and the difference between the horn outputs may be called a difference signal because it takes the difference between the horn outputs.

On the other hand, there are various configurations of the tracking receiver and the power feeding circuit for processing the reference signal and the error signal to obtain a voltage proportional to the pointing error of the antenna. As shown in "Satellite Computing", there are roughly three-channel system, two-channel system and one-channel system.

The 3-channel system is provided with a high-frequency amplifier, a frequency converter, an intermediate-frequency amplifier, an AGC amplifier, etc. for 3 channels for 3 signals of a reference signal and 2 error signals, in order to normalize the amplitude of the error signal with the reference signal. AGC is applied, each error signal is detected with the phase of the reference signal as a reference, and an angle error DC output signal in the east-west and north-south directions is obtained.

In the 2-channel system, two error signals are given a 90 ° phase difference and are orthogonally synthesized, or are periodically switched by a switch to make the error signal system into one channel, and a high frequency amplifier, a frequency converter, Intermediate frequency and AGC
This is a method in which an amplifier is used for two channels of a reference signal and an error signal, and the error signal is separated and output again corresponding to each two-dimensional error at the detection stage.

In the 1-channel system, not only the error signal but also the 3 signals including the reference signal are all combined or switched to form 1 channel, and the high frequency amplifier, frequency converter, intermediate frequency and AG
This is a system that requires only one channel for a C amplifier and the like. There are various methods for converting three signals into one channel. After two error signals are orthogonally combined, low frequency phase modulation or amplitude modulation is performed to combine with a reference signal. Both error signals have different phases. A method of combining after phase modulation or amplitude modulation with a low frequency signal, and then combining with a reference signal, after performing phase modulation with different phase shift amounts on both error signals, and combining
Furthermore, the method of combining with the reference signal, the error signal is periodically switched by the switch, only one of the error signals is output, and after performing phase modulation or amplitude modulation on this,
There is a method of combining with a reference signal, a method of switching three signals with a switch, and a method of outputting only one signal.

Therefore, the power supply circuit output signal changes depending on the number of channels of the tracking receiver, and outputs 3 signals in the 3-channel system, 2 signals in the 2-channel system, and 1 signal in the 1-channel system.

In addition, some methods of arranging a signal synthesizing circuit for synthesizing received signals from a plurality of ground stations and supplying the synthesized signals to the tracking receiver can be considered.

One is to have a signal combining circuit for each of the three signals of the reference signal of each system and the two-dimensional error signal, and to combine the signals of the two systems. After channelization, a method of synthesizing two systems of signals by providing a signal synthesizing circuit for two signals of the reference signal and the one-channel error signal, and further synthesizing the reference signal and the two-dimensional error signal three signals There is a method in which one channel is formed by switching and then one signal synthesizing circuit is provided to synthesize two systems of signals.

Therefore, if there are two ground stations, three in the three-channel system.
In the two-channel system, two signal combining circuits are required in the two-channel system and in the one-channel system.

In FIGS. 1 and 2, one horn is used to combine the reference signal and the error signal into one channel.
Shown is the case where the feed circuit output is obtained as one signal and the two feed circuit output signals from the two ground stations are input to the tracking receiver using one signal combining circuit. In addition, it is necessary to change the number of horns, the number of output signals of the feeding circuit, and the number of signal combining circuits depending on the method used.

〔The invention's effect〕

As described above, according to the present invention, the antenna pointing error for the earth station n station can be obtained at the same time. Therefore, even if one of the lines is disconnected, the antenna pointing direction can be controlled by the other line. The operation rate of the pointing device is greatly improved, and the redundant system can be connected, resulting in high reliability. Further, in the present invention, since the antenna pointing error for the n stations of the earth station can be obtained at the same time, the above-mentioned JP-A-55-74
It is also possible to detect the rotation angle of the yaw axis of the satellite by the same principle as 221.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a configuration in which two conventional pointing direction detection systems are provided, and FIG. 2 is a configuration diagram of one embodiment of the present invention. 1 ... Earth, 2a, 2b ... Ground station, 3 ... Satellite antenna mirror surface, 4a, 4b ... Feeding horn and feeding circuit, 5a, 5b ...
… Tracking receiver, 6a, 6b …… Antenna pointing error output signal,
7 ... Yaw angle calculation circuit, 8 ... Yaw angle signal, 9 ... Signal synthesis circuit, 10 ... Frequency converter, 11a, 11b ... Filter, 12a, 12b ... Demodulator

Claims (1)

(57) [Claims] 1. A feed horn formed by assembling one or a plurality of feed horns for directivity detection by a monopulse tracking method, and a mirror surface for reflecting a beam of the feed horn and directing the beam in a desired direction. When the center of the directional direction of the antenna composed of the feeding horn and the mirror surface is directed to the target ground station, the signal having the maximum reception level is used as a reference signal, and the center of the antenna is directed to the target ground station. When the received signal level is minimized, the received signal level increases as it deviates from the target direction, and one or more inverted signals whose phases are centered around the target direction are used as error signals. In this case, after the error signal is subjected to a predetermined modulation, a signal combined with the reference signal or a signal in which the error signal and the reference signal are sequentially switched at regular intervals is output on one line. If there are multiple error signals, the signal obtained by combining the error signals with a specified phase difference is further modulated by the specified signal and then combined with the reference signal, or by the specified modulation. The error signal is combined with the reference signal, or the error signal and the reference signal are sequentially switched at fixed time intervals. When there are a plurality of, the error signals have a predetermined phase difference, or a signal obtained by performing a predetermined modulation and combined, or a signal obtained by sequentially switching each error signal at regular time intervals to the error signal line, In addition, the reference signal is output to the line for the reference signal, or the reference signal and at least one error signal are obtained from the output signal of the power feeding horn and are output through separate lines. An antenna for a satellite using the monopulse tracking method, which has a power feeding circuit configured as described above and a tracking receiver that receives the output signal of the power feeding circuit and obtains a DC voltage approximately proportional to the antenna pointing error. In the above, the n stations (n is an integer of 2 or more) transmitting directivity direction detection signals having different frequencies from each other to the power feeding horn and the power feeding circuit.
And a signal synthesizing circuit that is provided corresponding to each ground station and that adds and synthesizes each one or more output signals of the plurality of power feeding circuits to output, and at least one unit that receives the output of the signal synthesizing circuit The tracking receiver of the tracking receiver is provided in the high frequency section or the intermediate frequency section.
Depending on the frequency of the direction detection signal transmitted by the ground station of the n stations received from each of the ground stations, using n sets of filters for extracting the signals and the signals extracted by the respective filters, An antenna pointing direction detecting device, comprising: n demodulators, each of which obtains a DC voltage approximately proportional to an antenna pointing error with respect to each ground station.