JP2001111467A - Automatic satellite tracking communication method and apparatus, and satellite communication system - Google Patents

Abstract

(57) [Summary] [Problem] When transmitting and receiving to and from a satellite moving in an elevation range,
Communication is interrupted at the timing of switching from a satellite that exits the elevation range to a satellite that newly enters. A receiving device (or a transmitting device) includes two antennas (11, 11 '), and a control device (13) receives a signal from a receiving RF (12) and a signal from a sensor (17) such as a gyro while receiving with the antenna (11). Then, a control signal for moving the antenna 13 to the direction of the satellite being tracked is output to the drive system 14. At the same time, the position of the satellite being tracked is calculated by the satellite position calculating device 15, and when the position reaches the end point of the elevation range, it is directed to the start point of the elevation range via the antenna control device 13 'and the drive system 14'. The tracking of the waiting antenna 13 'is started. The reception switching device 25 selects one of the signals received from both antennas during the switching timing, which has higher strength. In the case of a transmission device, transmission is performed from both antennas during the switching timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication apparatus using a plurality of artificial satellites, and more particularly to a communication method and apparatus for tracking a quasi-geostationary satellite such as a long elliptical orbit satellite.

[0002]

2. Description of the Related Art A 24-hour service of broadcasting and communication is available for a specific service area, and a continuous service is provided within the service area without being affected by shadows due to terrain and buildings. As a communication system, a technology using a quasi-geostationary orbit satellite has attracted attention.

A quasi-geostationary orbit satellite moves on a predetermined orbit, unlike a geosynchronous satellite that always appears to be stationary when viewed from the ground, and this movement connects a tangent to the ground on which the satellite is viewed and the ground. The elevation angle (α) with the line segment fluctuates. If this elevation angle is kept at a certain angle (α ₀ ) or more,
It is possible to avoid a phenomenon (shadowing or blocking) in which transmission or reception with a satellite becomes impossible due to interference with buildings or forests.

[0004] For this purpose, it is necessary to set a trajectory at which the apogee comes above the service target area, prolong the time during which the satellite stays in a high elevation angle range, and secure a stable communication line. In addition, it is necessary to configure a continuous communication system by orbiting a satellite in a plurality of quasi-geostationary orbits so that when one satellite's elevation angle deviates from a certain angle α ₀ , another satellite enters the angle. is there. One of the quasi-geostationary orbit satellites is a long elliptical orbit satellite.

Japanese Patent Application Laid-Open No. 11-34996 discloses an example of a communication system using a long elliptical orbit satellite (HEO: Highly Ellipitical Orbit). here,
Three or four oblong trajectories are set, and each elliptical trajectory is arranged such that an apogee comes in the zenith direction of a specific service area. As a result, a predetermined elevation angle range (α ₀ ) in the zenith direction as viewed from the service target area is increased, and at least one artificial satellite orbiting each orbit is always “visible”.
It is operated so that. The elliptical orbits orbiting each satellite are slightly different, but are set to be almost the same in the elevation range (α ₀ ). Thus, for example, even when three satellites rotate in a 24-hour cycle, control can be performed such that one satellite is always “visible” in the elevation angle range (α ₀ ).

[0006] The terrestrial transmitter / receiver tracks the HEO in the elevation range, so that the signal from the antenna controller is received so that the strength of the signal from the satellite received from the transmission / reception antenna is optimized. The polarization angle motor and the azimuth angle motor are driven to control (track) the direction of the antenna.

[0007]

In a communication system using a quasi-geostationary orbit satellite, an orbit is set so that an apogee is located above the service area, and the satellite has a high elevation angle range (α ₀ ).
As a result, the communication line can be stably secured for a long time. But,
For example, if the orbital cycle of a satellite is 24 hours, at least three satellites are required to make the satellite always exist in the elevation range (α ₀ ), and the movement of the plurality of satellites must be tracked from the earth station. There is. In this case, the elevation range (α
_{Since the} satellites entering ₀ ) are switched, the following problems occur when switching satellites.

FIG. 4 is an explanatory view of a quasi-geostationary orbit satellite. The quasi-geostationary orbit satellites 111 and 110 move in predetermined orbits 130 and 131 around the earth 60 (satellite not shown moves in orbit 132). However, the trajectories in the elevation angle range are almost the same, and are represented by the trajectory 130. In the figure, the satellite 1 currently in orbit 130 is shown.
11 is capable of transmitting and receiving to and from the ground, and is moving from left to right in the figure. The satellite 110 in the orbit 131 moves at a predetermined interval from the satellite 111 so as to follow the satellite 111. At this time, the antenna 120 installed in the earth station is tracking the movement of the satellite 111.

A section 142 surrounded by the on-orbit position 135 and the on-orbit position 136 is a communicable section, and is a communicable elevation angle range α ₀ in which transmission and reception between the earth station and the satellite are possible. Also,
A left section 141 from the orbit position 135, right section 143 from the orbit position 136 in the incommunicable interval, outside the scope of communicable elevation range alpha _0. For example, three satellites orbit three quasi geostationary orbits each in a 24-hour cycle,
In the section 142 having the elevation angle range α ₀ , there is always one group. Now, when the satellite 111 passes through the orbital position 136, communication with the earth station becomes impossible. At this time, the satellite 110 passes through the on-orbit
2 and transmission / reception with the ground becomes possible. This timing is hereinafter referred to as “satellite switching timing”.

According to the quasi-geostationary orbit satellite, one satellite always exists in the communicable section 142, and control can be performed so that two satellites coexist for a very short time at the satellite switching timing. At this time, in order to realize seamless communication, as shown in FIG.
To the satellite 110, and the antenna 120 installed in the earth station must always be directed (tracked) toward the moving satellite.

However, it takes time (several seconds) to turn the antenna 120 from the satellite 111 to the satellite 110 at the satellite switching timing, during which time the signal is interrupted. In broadcasting and information transmission, it is difficult to recover a lost signal due to unilateral or transient, and if necessary, there is no alternative but to retransmit. However, retransmission not only takes time and effort, but also does not solve real-time or emergency cases. For example, if communication is interrupted at the timing of switching satellites while an image of a patient's condition is being transmitted between an ambulance and a hospital every moment, human lives may be involved.

Also, the earth station is not a fixed station on the ground,
For mobile stations installed in cars, trains, ships, airplanes, etc.,
The elevation angle range in which communication with the satellite varies depending on the latitude and longitude of the earth station. In this case, unless the elevation angle range is corrected in accordance with the current position (coordinates) of the mobile station, there is a problem that not only satellite switching timing but also normal satellite tracking cannot be performed accurately.

An object of the present invention is to provide a communication method and apparatus for tracking a quasi-geostationary satellite capable of overcoming the problems of the prior art and ensuring stable transmission and reception without signal interruption even at the time of satellite switching. It is in. Another object of the present invention is to provide a communication device and a communication system that can secure stable transmission and reception by accurate satellite tracking including at the time of satellite switching even in the case of a mobile station.

[0014]

According to a first aspect of the present invention, which achieves the above object, one always moves on an orbit within a predetermined elevation range that is visible from an earth station in a service area. In a communication method for transmitting and receiving between a satellite and an earth station while tracking an artificial satellite, one of the antennas provided in the earth station is tracking an artificial satellite moving in the elevation range, and the other antenna is in the orbit. At the satellite switching timing when the artificial satellite being tracked comes out while the new artificial satellite enters the elevation angle range while waiting for the tracking start point predetermined above, the new artificial satellite by the other antenna Is started.

It goes without saying that the roles of the one antenna and the other antenna are switched after the satellite switching timing. In addition, the above “visible” does not mean that it can be seen with the naked eye, but means a satellite tracking control ground station or a satellite communication transceiver installed on the earth, or a terrestrial-side facility and a satellite equivalent to these. Means that there is a satellite in a spatial area where communication with the satellite can be performed by radio waves or light.

Further, when the earth station performs a receiving operation, one of the received signals received from both antennas is selected and received at the satellite switching timing. Alternatively, when the earth station performs a transmission operation, a transmission signal is transmitted from both antennas at the satellite switching timing.

[0017] Further, the earth station may determine whether a satellite position in orbit determined for the tracking satellite has reached an end point as viewed in a satellite movement direction in the orbit within the elevation range, and / or
Alternatively, the satellite switching timing is determined by determining whether the satellite position of the new artificial satellite determined from the satellite position has reached the tracking start point.

According to this, since one satellite and two satellites that enter and exit at the satellite switching timing coexist temporarily in the elevation angle range that becomes visible, the two satellites are captured by capturing this timing. , The switching of satellites can be performed smoothly and without signal interruption.

According to a second aspect of the present invention, which achieves the above object, one or more satellites which are always moving on an orbit within a predetermined elevation range visible from the earth station in the service area are tracked. A communication method for transmitting and receiving between a transmitting device and a receiving device of an earth station via the satellite, wherein the receiving device having only one antenna interrupts a received signal being received via the artificial satellite. It is characterized in that it is determined whether or not the satellite position obtained while tracking the artificial satellite has passed the end point of the elevation angle range, and when the satellite position has passed, it is displayed that the cause of the interruption of the received signal is due to the satellite switching timing.

Further, while the transmitting device having only one antenna is transmitting a transmission signal while tracking the artificial satellite, it is determined whether the satellite position of the artificial satellite has reached the end point of the elevation angle range. Then, the transmission of the transmission signal is interrupted for a predetermined time, during which the antenna is directed to the start point of the elevation range, and the transmission is restarted after the predetermined time has elapsed.

Alternatively, the transmitting device waits for the second antenna toward the start point of the elevation range, and transmits the transmission signal while tracking the artificial satellite with the first antenna, and transmits the satellite position of the artificial satellite. It is determined whether or not the end point of the elevation range has been reached, and when it has arrived, the transmission of the transmission signal is interrupted for a predetermined time, and after the predetermined time has elapsed, another antenna appearing in the elevation range by the second antenna. The transmission is restarted by tracking the artificial satellite.

Further, the reception device is characterized in that the reception device directs its own antenna to the start point of the elevation angle range within the predetermined time and restarts transmission after the predetermined time has elapsed.

According to this, even when the receiving apparatus has only one antenna, the transmission time from the transmitting apparatus for a predetermined time necessary to redirect the antenna from the end point to the start point of the elevation angle range at the satellite switching timing. Since the transmission signal is temporarily interrupted, the signal can be received without interruption. In addition, when the interruption is caused by the satellite switching timing on the receiving side and also on the transmitting side, the cause is clearly indicated, so that a sense of security can be given to the user.

An apparatus for realizing the method according to the present invention is provided on a trajectory in a predetermined elevation range which is visible from a service area.
In a satellite automatic tracking communication device having a control device that always tracks a moving artificial satellite and a transmitting and receiving device that transmits and receives the artificial satellite, two antennas that are moved by different driving devices are used. The control device calculates a position of one of the antennas on the orbit of the satellite being tracked, and includes a satellite switching timing determination unit that determines that the satellite has reached the end point of the elevation angle range. Is confirmed, and tracking of the other waiting antenna is started toward a predetermined tracking start point on the trajectory.

The control device may determine, in addition to or in place of the satellite switching timing determination section, the position of another artificial satellite that is within or approaching the elevation angle range from the position of the tracking artificial satellite. A means is provided for determining whether or not the tracking start point has been reached, confirming that the tracking start point has been reached, and configured to start tracking of the other antenna that is waiting for the tracking start point. I do.

The tracking start point is set at a start point as viewed in the satellite movement direction on the orbit within the elevation range, or at a predetermined orbit position opposite to the satellite movement direction from the start point. In the case of the above-mentioned predetermined orbital position, tracking starts before another satellite enters the elevation range.

A communication system implementing the method of the present invention comprises:
A transmitting apparatus for transmitting and receiving via a plurality of artificial satellites arranged so as to always move at least one orbit on an orbit within a predetermined elevation range visible from the service area, and an artificial satellite within the elevation range And a satellite communication system including a receiving device, wherein the receiving device includes one antenna, a control device that tracks the artificial satellite and controls the attitude of the antenna, and receives a signal from the artificial satellite using the antenna. Means for calculating the satellite position on the orbit of the artificial satellite whose antenna is being tracked by the control device, and the control unit determines the end point of the elevation angle range when the reception signal is interrupted. Means for judging whether or not the signal has passed, and a display device for indicating that the cause of the interruption of the received signal is due to satellite switching timing.

The transmitting device includes one or two antennas, a control device that tracks the artificial satellite and controls the attitude of the antenna, and transmits a transmission signal to the artificial satellite via the antenna. Means for calculating a satellite position on the orbit of the artificial satellite whose antenna is being tracked by the control device, and means for determining whether the satellite position has reached the end point of the elevation angle range. A transmission signal from the transmission unit is interrupted for a predetermined time after confirming that the end point has been reached.

Further, a database for comparing the elevation angle of the satellite with the position of the earth station is provided in the receiving device or the transmitting device. As a result, in the case of a mobile station in which the visible elevation angle range fluctuates, tracking control can be performed speedily and the device can be simplified.

A semi-geostationary orbit satellite is used as the plurality of artificial satellites. This quasi-geostationary satellite includes a quasi-zenith satellite, a synchronous orbit satellite, a mobile satellite, and a long elliptical orbit satellite. In particular, long-elliptical orbit satellites that can place an apogee in the zenith direction and set a high elevation range can avoid phenomena (shadowing and blocking) in which buildings and forests interfere with transmission and reception with the satellite, It is suitable. However, the present invention is also applicable to other orbiting satellites, such as low-elevation orbiting satellites, as long as the orbits of a plurality of satellites are substantially the same in the elevation range from the earth station.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. First, a long elliptical orbit satellite (HEO) will be described as an example of a quasi-geostationary orbit satellite, and then a plurality of embodiments of a satellite tracking communication system will be described.

FIG. 2 is an explanatory diagram of a long elliptical orbit. In the long elliptical orbit, the eccentricity e of the orbit around the artificial satellite is larger than zero and smaller than 1. Preferably, for example, the orbit inclination angle is 3
The eccentricity e is in the range of not less than 7 degrees and not more than 44 degrees and less than 0.24. Alternatively, the orbit inclination angle i is larger than 40 degrees and 44 degrees or less, and the eccentricity e is 0.24 or more and 0.3
The range is 5 or less. Such a long elliptical orbit satellite has an elevation angle α higher than that of the geostationary satellite (preferably, the elevation angle is 70 degrees or more).

The elliptical orbit 50 is defined by six orbital elements having a major axis of the radius a, an eccentricity e, an orbital inclination angle i, an ascending right ascension Ω, a perigee argument ω, and a right near point separation angle θ. These are defined as values at a certain reference time. The orbital major radius a is the major radius of the ellipse. Is the angle between the line segment Rp connecting the perigee 53 and the focal point 51 of the ellipse and the line segment connecting the satellite 110 in orbit and the focal point 51 of the ellipse, and ranges from 0 to 360 degrees.

The eccentricity e represents the flatness of the ellipse. The eccentricity e is expressed by the following equation 1 between the perigee radius Rp, the apogee radius Ra which is a line segment connecting the apogee 52 and the focal point 51, the orbital major radius a and the orbital minor radius b. There is a geometric relationship.

[0035]

[Number 1] Rp = a (1-e) Ra = a (1 + e) b = a √ (1-e 2) e = (Ra-Rp) / (Ra + Rp) 3, the focal point of the trajectory of FIG 51 Shows a long elliptical orbit when the earth 60 is placed in FIG. The elliptical orbit crosses the equatorial plane 61 from the southern hemisphere toward the northern hemisphere at the ascending intersection point 62, and becomes a perigee 63 and an apogee 64. The angle between the equatorial plane 61 and the orbital plane is the orbital inclination angle i, which is in the range of 0 to 180 degrees. The ascending intersection RA is an angle measured from the vernal equinox direction to the east around the point at which the orbit crosses the equatorial plane from the southern hemisphere to the northern hemisphere, and ranges from 0 to 360 degrees. The perigee argument ω is defined by an angle obtained by measuring the position of the perigee 63 on the orbital plane from the ascending intersection point 62, and has a range of 0 to 360 degrees.

FIG. 3B shows the relationship between the elliptical orbit and the elevation angle α. The angle between the tangent line 66 of the point 65 of the earth station and the line segment connecting the point 65 and the satellite 110, that is, the angle between the ground and the satellite is the elevation angle α.

In the communication system of the present embodiment, three (or four) oblong trajectories are set, and one trajectory is set for each trajectory.
It is operated using a group of artificial satellites. Each orbit cycle is 24 hours, and is operated with an error of about ± 10 minutes.

Next, an embodiment of a communication device using a plurality of long elliptical orbit satellites will be described. In the first embodiment, a satellite switching timing tracking method including two antennas and a communication device will be described. In the second embodiment, a satellite switching timing transmission / reception system having one antenna and a satellite communication system will be described.

Embodiment 1 FIG. 5 is a conceptual diagram showing a method of tracking two antennas at satellite switching timing. The quasi-geostationary orbit satellites 110 and 111 are moving from left to right on the representative orbit 130 at predetermined time intervals. Section 14 between position 135 and position 136 on the orbit
When there is a satellite in the elevation angle range α ₀ of ₀ , the satellite 11 is shown in the figure.
1 and the antenna 121 of the ground station.
As the satellite 111 moves in orbit from right to left,
The antenna 121 always tracks the direction of the satellite 111, and continues transmitting and receiving between them. When the communicating satellite 111 passes through the position 136, the elevation angle α when the satellite 111 is viewed from the antenna 121 decreases, and communication becomes difficult. At this time, since the next satellite 110 passes through the position 135, this satellite 1
If there is an antenna that tracks 10, transmission and reception with the earth station can be continued without interruption.

In the communication system of the first embodiment, two
The base antennas 120 and 121 are provided, and when the antenna 121 is tracking the satellite 111, the antenna 120 waits for the position 135 on the orbit, and starts tracking the satellite 110 when the satellite timing comes. That is, when the satellite 111 passes through the position 136 and transmission and reception by the antenna 121 become impossible, the antenna 120 starts tracking the satellite 120 appearing at the position 135. Therefore, position 13
If the satellites 110 and 111 coexist for a short time (the time at which the antenna 120 can start tracking at the satellite switching timing) in the elevation angle range α ₀ between the position 5 and the position 136, the transmission with the earth station is not interrupted. .

The long elliptical orbit satellite of the present system is controlled so that one satellite always exists in the elevation angle range with respect to the ground station in the service target area. Actually, each orbital period has an error, so only the time that can cover the error is
The two satellites are operating simultaneously with overlapping periods in the elevation range. Therefore, during this overlap period, the satellite 11
1. Since communication with both satellites 110 becomes possible, the earth station selects one from the signal strength of both. Eventually, when transmission and reception with the satellite 111 become impossible, the antenna 121
Is completed, and only the tracking by the antenna 120 is performed. Thereafter, the antenna 121 is initialized toward the position 135 and waits until the next satellite appears.

FIG. 1 is a functional block diagram of the satellite automatic tracking communication apparatus according to the first embodiment. Two antennas 11, 1
1 'is covered with radomes 16 and 16' for overcoming rain and wind. Antennas 11 and 11 'respectively track different satellites, receive signals from the satellites, and receive RF signals 12 and 1'.
Receive at 2 '.

In order to control the attitude (azimuth) of the antenna 11 and track the satellite, the signal from the sensor 17 and the received RF
The control unit 13 takes in the received signal from the satellite by the control unit 12. The control device 13 performs azimuth control for tracking the satellite,
The driving device 14 is moved to point the antenna 11 toward a satellite (for example, the satellite 111 in FIG. 5).

The sensor 17 comprises an accelerometer and a gyro for measuring angular velocity and moment of inertia, and detects position information when the earth station is a mobile station. If the earth station is a fixed station, the sensor 17 may be omitted, and a database of the time and satellite azimuth determined in advance may be used.

The azimuth of the tracking antenna 111 is fetched from the control device 13 into the satellite position calculating device 15 and the position of the next satellite (for example, the satellite 110 in FIG. 5) is calculated.
Transfer to control device 13 '. When the controller 13 'determines that it is the satellite switching timing based on the satellite position, the controller 13' issues a tracking start command to start the tracking of the antenna 11 'by the driving device 14. As a result, the antenna 11 ′ moves in the direction of the satellite 110 from the tracking start point direction in the standby state, and thereafter, the same tracking as that of the above-described antenna 11 is performed. On the other hand, the satellite tracked earlier (for example, satellite 11 in FIG. 5)
When the position of 1) passes the position 136 at the switching timing, the control device 13 transmits a tracking end command, and moves the driving device 14 to move the antenna 11 to the tracking start point direction (position 1).
Wait for 35).

Here, the tracking start point azimuth is directed, for example, to the position 135 in the elevation angle range α ₀ in FIG. However,
As shown in FIG. 6, the control unit 13 waits for a position further ahead of the position 135 as the tracking start point direction, and when the next satellite position calculated by the satellite position calculation unit 15 reaches the tracking start point, the control unit 13 starts tracking. A command may be issued. According to this, tracking starts when the signal from the satellite is weak, so that tracking succeeds at an early timing, and the overlap period of the two satellites can be short. It is also advantageous for a mobile station whose elevation angle range varies.

At the satellite switching timing, signals are received from both antennas 11 and 11 '. Receive RF 12,1
The reception signal extracted by 2 ′ is received by the reception switching device 2
5, the one with the larger signal strength is selected. The selected signal is displayed on the screen of the display device 22 via the receiving device 21. As a result, even at the satellite switching timing, continuous reception is possible.

The above is the description of the reception operation. In the case of the transmission operation, the antennas 11 and 11 'of FIG. 1 are made to function for transmission, the reception RHs 12 and 12' are transmitted to the transmission RH, and the reception switching device 15 is transmitted. By replacing the receiving device 21 with the transmitting device in the switching device, it is possible to perform continuous transmission at the satellite switching timing.

At the time of satellite switching at the time of transmission, transmission is performed from both of the antennas 11 and 11 '. The transmission is stopped, and in response to this, the control device makes the antenna stand by toward the tracking start point direction. Note that, for example, a reception clock for synchronizing between the satellite and the ground station can be used as the reception signal captured by the antenna tracking control device 13 for satellite tracking.
It goes without saying that a transmitting and receiving station can be configured by including both the receiving system and the transmitting system.

A database of the satellite elevation angle and the position of the earth station (earth coordinates) is set in the satellite position calculating device 15 in advance, and the position of the earth station is detected by the clock synchronized with the clock mounted on the satellite. The elevation angle of the position is read from the database, and the satellite position can be calculated together with the signal from the sensor 17. According to this, the elevation angle range and the satellite position in the mobile station can be calculated quickly.

FIG. 7 shows the flow of the satellite switching process according to the first embodiment. This processing is mainly performed by the controller 13
It is executed every sampling cycle. First, the position information of the earth station (sensor 17) and the received signal from the satellite (received RF1
The signal of 2) is fetched (s101), the direction of the satellite being tracked is calculated, and an antenna control signal is output to the drive system 14 (s102). Next, the on-orbit position of the tracking satellite is calculated from the satellite azimuth, and further the on-orbit position of the satellite appearing in the elevation angle range α ₀ is calculated (s103).

Based on the satellite position appearing next, it is determined whether the start point is the satellite switching timing (s104). If it is the start point (Yes), tracking by the antenna waiting at the tracking start point is started (s105). . The tracking start command at this time is output from another control device 13 ′, but may be output from the control device 13. Alternatively, the control devices 13 and 13 'may have a common satellite switching timing determination function.

On the other hand, in s104, if the satellite position is not the tracking start point (No), based on the position of the tracking satellite,
It is determined whether or not the satellite switching timing has ended (s106).
If it is the end point (Yes), a tracking end command is issued to the antenna on the end side, and the antenna is moved to the tracking start point direction and made to stand by (s107). If it is not the end point in step s107 (No), it is not the satellite switching timing, so the tracking control in this cycle ends.

During the period from the start point to the end point of the satellite switching timing, the control devices 13 and 13 'repeat the control (s102) for tracking each satellite in each sampling cycle. During this time, in the reception operation, the reception switching device 25 selects a signal from one antenna, and in the transmission operation, the transmission switching device transmits to both antennas.

The orbital positions of the two satellites can be determined if one is known. The start point of the satellite switching timing is not limited to the start point of the elevation angle range α ₀ , but may be the tracking start point direction set by the present system as in the case of FIG. Further, it is not essential to determine the end point of the satellite switching timing. Tracking may be terminated at the timing when the satellite passes the end point and communication becomes impossible, and the antenna may be moved to the tracking start point direction.

As described above, according to the first embodiment, two antennas are provided in the earth station, and at least the satellite switching timing
Since two satellites in the elevation range and the next satellite appearing in or near the elevation range are tracked, reception or transmission is not interrupted, and stable communication can be secured. Further, since a database for comparing the satellite elevation angle with the position of the earth station (earth coordinates) is provided, it is easy to calculate the satellite position for tracking, and it is particularly suitable for a mobile station whose elevation angle varies.

[Second Embodiment] A communication device according to a second embodiment of the present invention.
Is a communication system using a long elliptical orbit satellite similar to that of the first embodiment, and is a communication system in which only one satellite tracking antenna is provided in an earth station to avoid the above-described problem of satellite switching timing. .

FIG. 8 is a functional block diagram showing the configuration of the communication apparatus according to the second embodiment. Elements that are the same as in FIG. 1 are given the same reference numerals. Although this communication device is configured for both transmission and reception, the transmission / reception RF 30 and the transmission / reception device 33 are switched between the reception operation and the transmission operation described in the first embodiment by the transmission / reception switching device 32. The main difference from the first embodiment is that the control device 3
1 operation.

FIG. 9 is a flowchart showing the transmission operation and the reception operation of the communication apparatus according to the second embodiment, which will be described with reference to the trajectory of FIG. 4 in the case where there is one antenna. In the transmission operation (a), the transmission from the antenna 11 (the antenna 120 in FIG. 4) to the satellite 111 is started at the timing when the satellite 111 has passed the orbital position 135. From here, the control device 31 fetches a signal such as the reception RF 12 (s201), calculates a satellite azimuth, outputs an antenna attitude control signal (s202), and tracks the satellite 111, as in FIG.

Next, the satellite position 111 is determined based on the satellite direction.
Is calculated (s203), and it is determined whether it is the end point of the satellite switching timing (s204). That is, it is determined whether the satellite 111 has reached the orbital position 136, and if it is still (No), the control in this cycle ends. On the other hand, if the satellite 111 has reached the orbital position 136 (Yes), a tracking end command is output to the drive system 14 (s205), and the tracking of the satellite 111 by the antenna 11 ends. At the same time, a transmission stop command is also issued to the transmission / reception device 33 (s206), and the transmission / reception device 33 interrupts the output of the transmission signal.

Next, the control device 31 outputs a tracking start command, and the drive system 14 moves the antenna 11 toward the orbital position 135 (s207). After moving the antenna, satellite 11
0 starts tracking, and at the same time, the control device 31 issues a transmission restart command to the transmission / reception device 33 (s208).
3 starts outputting the transmission signal from the point of interruption. The transmission signal interruption time Ts during this time is slightly longer than the time required to turn the satellite 111 from the orbital position 136 to the position 135.

Next, the receiving operation of FIG. 9B will be described.
The control device 31 captures a signal from the sensor 17 or the like (s
301), the satellite orientation is calculated, an antenna attitude control signal is output (s302), and the satellite 111 is tracked. Also,
The satellite position 111 is calculated based on the satellite azimuth (s3
03). The signal received by tracking is transmitted and received by the transmitting / receiving device 33.
Is displayed on the screen of the display device 22.

During tracking of the satellite, the presence or absence of interruption of the received signal is monitored (s304), and if there is no interruption, the processing of this cycle is terminated. On the other hand, if there is an interruption, it is determined whether the cause is the satellite switching timing (s305). If the cause of the interruption is not the satellite switching timing, it is not directly related to the present embodiment, so the description is omitted. However, diagnosis of another cause may be performed in some form. However, if the cause of the interruption is the satellite switching timing, the fact is displayed on the screen of the display device 22 (s306).

FIG. 10 shows a display example of reception interruption at the satellite switching timing. Since the reception interruption at the satellite switching timing can be resumed after the time Ts, this display gives the user a sense of security and improves the reliability of the communication device.

When the interruption of the reception is caused by the satellite switching timing, the control device 31 immediately moves the antenna 11 toward the orbital position 135 (s307), tracks the satellite 110, and resumes the reception (s308). Since the interruption time Ts due to the transmission operation is adapted to the time at which the antenna on the receiving side can change its direction and resume tracking, the receiving side can receive without losing the transmission signal.

According to the second embodiment, even when only one antenna is used, loss of a received signal at the satellite switching timing can be avoided, so that a compact and inexpensive communication device can be provided. In addition, since the reception interruption at the satellite switching timing is displayed to that effect, a sense of security is given to the user, and the reliability of the receiving device can be improved. When the transmission signal is interrupted at the satellite switching timing, a message to that effect may be displayed on the screen.

Next, a modification of the second embodiment will be described. This modification is a system in which a transmitting device having two antennas and a receiving device having one antenna form an earth station via a long elliptical orbit satellite.

When the tracked antenna passes through the orbital position 136, the transmitting device interrupts the transmission, and restarts the transmission after a predetermined time Ts from the antenna waiting for the orbital position 135. On the other hand, the receiving device performs the same operation as in the second embodiment. That is, a single antenna receives while tracking a satellite in the elevation range, and if the reception signal is interrupted, the cause is determined. If the interruption is due to the satellite switching timing, the antenna is turned to the orbital position 135 and the satellite is detected after Ts. Tracking is started and reception is resumed.

According to this, it is possible to perform reception without signal loss due to satellite switching timing. For example, it is easy for a transmitting device to have two antennas such as a broadcasting station, and only one receiving device has one antenna. It is suitable for a communication system including mobile stations that cannot be provided.

[0070]

According to the present invention, the transmitting device and / or the receiving device include two antennas, and the satellites and their antennas that have already been tracked at the satellite switching timing, and the satellites and their antennas that are newly tracked. By temporarily overlapping the communication by the two paths, the switching of the communication from one antenna to the other antenna can be performed without interruption of the signal,
This has the effect of ensuring stable communication.

Further, according to the present invention, when at least the receiving device has only one antenna, the transmitting device switches the satellite to be communicated from the end position on the satellite orbit in the communicable section to the start position. When the transmission is interrupted for a certain time,
On the other hand, when the reception signal is interrupted by the satellite switching timing, the antenna direction is changed to the start point within a fixed time during which the transmission is interrupted, so that stable communication without interruption of the reception signal can be secured, A compact and inexpensive communication device can be provided. Further, when transmission / reception is interrupted, the fact that it is the satellite switching timing is displayed, so that the user is given a sense of security and the reliability can be improved.

Further, according to the communication device of the present invention, since the database is provided with the relation between the satellite elevation angle and the earth station position, the satellite position and the communicable section thereof can be quickly obtained. Suitable for mobile stations that fluctuate.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a communication device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a long elliptical orbit as an example of a quasi-geostationary satellite orbit to which the present invention is applied.

FIG. 3 is an explanatory diagram in the case where the earth is placed at the focal point of the long elliptical orbit in FIG. 2;

FIG. 4 is an explanatory diagram in the case of tracking a long elliptical orbit satellite with one antenna.

FIG. 5 is an explanatory diagram of an operation of satellite tracking by two antennas according to the first embodiment.

FIG. 6 is an explanatory diagram of an operation of satellite tracking according to a modification of the first embodiment.

FIG. 7 is a flowchart of satellite tracking control according to the first embodiment of the present invention.

FIG. 8 is a functional block diagram of a communication device according to a second embodiment of the present invention.

FIG. 9 is a flowchart of transmission / reception control according to the second embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a display example of an interruption cause in the second embodiment.

[Explanation of symbols]

11, 11 '... antenna, 12, 12' ... reception RF device, 13, 13 '... control device, 14, 14' ... drive device, 16, 16 '... radome, 17 ... sensor, 21 ... reception device, 22 ... Display device, 25 ... Reception switching device, 30 ...
RF transmission / reception device, 31: control device, 32: transmission / reception switching device, 33: transmission / reception device, 50: oblong orbit, 51: focal point, 52: apogee, 53: perigee, 60: earth, 61 ...
Equatorial plane, 62 ... Elevation point, 110,111 ... Satellite, 12
0, 121 ... antenna, 130 ... orbit, 135 ... orbital position (tracking start point), 136 ... orbital position (tracking end point),
142 ... communicable section (elevation angle range)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirofumi Higuchi 1-6-10 Uchikanda, Chiyoda-ku, Tokyo Inside Yagi Antenna Co., Ltd. (72) Koji Sakauchi 1-6-10 Uchikanda, Chiyoda-ku, Tokyo No. Yagi Antenna Co., Ltd. F-term (reference) 5K072 AA22 AA24 DD03 DD04 DD15 GG06

Claims (15)

[Claims] 1. A communication for transmitting and receiving between a satellite and an earth station while always tracking a moving artificial satellite in an orbit within a predetermined elevation range visible from an earth station in a service area. In the method, while tracking an artificial satellite that is moving in the elevation range with one antenna provided in the earth station, the other antenna is made to wait for a predetermined tracking start point on the orbit and newly set in the elevation range. A satellite automatic tracking type communication method, wherein the tracking of the new artificial satellite by the other antenna is started at a satellite switching timing when the artificial satellite enters and the tracking artificial satellite leaves. 2. The automatic satellite tracking according to claim 1, wherein when the earth station performs a receiving operation, one of the received signals received from both of the antennas is selected and received at the satellite switching timing. Type of communication method. 3. The communication method according to claim 1, wherein when the earth station performs a transmission operation, a transmission signal is transmitted from both antennas at the satellite switching timing. 4. The earth station according to claim 1, 2 or 3, wherein the satellite position in the orbit obtained for the tracking satellite reaches an end point as viewed in the satellite movement direction on the orbit in the elevation range. And / or determining whether the satellite position of the new artificial satellite determined from the satellite position has reached the tracking start point to determine the satellite switching timing. Tracking type communication method. 5. A transmission device of an earth station via a satellite while constantly tracking a moving artificial satellite on an orbit within a predetermined elevation range visible from an earth station in a service area. In a communication method for transmitting and receiving between receiving devices, a satellite obtained by tracking the artificial satellite when the receiving device having only one antenna interrupts a received signal being received via the artificial satellite. It is determined whether or not the position has passed the end point of the elevation range, and when the position has passed, it is displayed that the cause of the interruption of the received signal is due to the satellite switching timing. 6. The satellite device according to claim 5, wherein the transmitting device having only one antenna transmits a transmission signal while tracking the artificial satellite, and a satellite position of the artificial satellite reaches an end point of the elevation angle range. Determining whether or not the transmission has been completed, suspending the transmission of the transmission signal for a predetermined time, pointing the antenna toward the start point of the elevation angle range during that time, and restarting the transmission after the predetermined time has elapsed. Tracking type communication method. 7. The transmitting device according to claim 5, wherein the transmitting device waits for a second antenna toward a start point of the elevation range, and transmits the transmission signal while tracking the artificial satellite with the first antenna. It is determined whether the satellite position of the artificial satellite has reached the end point of the elevation angle range, and when it reaches, the transmission of the transmission signal is interrupted for a predetermined time, and after the predetermined time has elapsed, the elevation angle range is determined by the second antenna. A satellite automatic tracking type communication method characterized by tracking another artificial satellite appearing in (1) and restarting transmission. 8. The satellite according to claim 6, wherein the receiving device directs its own antenna to the start point of the elevation angle range within the predetermined time and restarts transmission after the predetermined time has elapsed. Automatic tracking communication method. 9. A control apparatus for tracking an artificial satellite that is always moving on an orbit within a predetermined elevation range visible from a service area, and a transmitting and receiving apparatus for transmitting and receiving to and from the artificial satellite. In a satellite automatic tracking type communication device, two antennas moved by separate driving devices are provided, and the control device calculates a position of one of the antennas on the orbit of the artificial satellite being tracked, and calculates the position of the elevation angle range. A satellite switching timing determination unit that determines that the vehicle has reached the end point is provided, and confirms that the vehicle has reached the end point, and starts tracking of the other antenna that is waiting for a predetermined tracking start point on the orbit. A satellite automatic tracking type communication device characterized in that: 10. The satellite according to claim 9, wherein the control device is in addition to or in place of the satellite switching timing determination unit, and another satellite that is in or close to the elevation angle range from the position of the tracking artificial satellite. Means for determining whether the position has reached the tracking start point, confirming the arrival at the tracking start point, and starting tracking of the other antenna waiting for the tracking start point. A satellite automatic tracking type communication device characterized in that: 11. The tracking start point according to claim 9, wherein the tracking start point is set to a start point viewed in a satellite movement direction on an orbit within the elevation angle range, or a predetermined orbit position opposite to the satellite movement direction from the start point. A satellite automatic tracking type communication device. 12. A plurality of artificial satellites arranged so as to always move on an orbit within a predetermined elevation range visible from the service area, and via an artificial satellite in the elevation range. In a satellite communication system including a transmitting device and a receiving device that perform transmission and reception, the receiving device includes one antenna, a control device that tracks the artificial satellite and controls the attitude of the antenna, and a reception from the artificial satellite. A receiving unit for receiving a signal via the antenna, and means for calculating a satellite position in the orbit of the artificial satellite being tracked by the antenna in the control device; and Means for determining whether the vehicle has passed the end point of the elevation range, and a display device for indicating that the cause of the interruption of the received signal is due to satellite switching timing. Communications system. 13. The transmitting device according to claim 12, wherein the transmitting device includes one or two antennas, a control device that tracks the artificial satellite and controls the attitude of the antenna, and transmits a signal to the artificial satellite. A transmitting unit for transmitting via the antenna, and means for calculating a satellite position in the orbit of the artificial satellite tracked by the antenna in the control device, and whether the satellite position has reached the end point of the elevation angle range A satellite communication system, comprising: determining means for determining that the end point has been reached, and interrupting a transmission signal from the transmission unit for a predetermined time. 14. The satellite communication system according to claim 12, wherein a database for comparing a satellite elevation angle and a position of an earth station is provided in the reception device or the transmission device. 15. The satellite communication system according to claim 12, 13 or 14, wherein the plurality of artificial satellites are quasi-geostationary orbit satellites such as elliptical orbit satellites.