JPH04314219A - Satellite communication system - Google Patents

Abstract

PURPOSE:To obtain the satellite communication system in which the alteration of the part between a master station and a backup station is ensured. CONSTITUTION:A backup station 2 sends a non modulation carrier whose frequency is f1 at the alternation of the part between a master station 1 and the backup station 2. When a portable station 3 detects the presence of the non modulation carrier, the station 3 sends a carrier interrupt request signal to a communication line 5. Upon the detection of the carrier interrupt request signal, a line MODEM section 11 for a communication line of the master station 1 stops the transmission of a transmission carrier to the communication line 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system having a standby earth station serving as a backup station for a monitoring and control earth station.

0002

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional satellite communication system. In the figure, 10 is a supervisory control earth station (hereinafter referred to as a master station) that performs communication and supervisory control;
2 is a supervisory control line modulation/demodulation unit that modulates and demodulates signals transmitted and received to the supervisory control line 6; 13 is an earth station 30;
and a monitoring control unit that monitors and controls the standby earth station 20, 1
4 is a transmitting/receiving unit that performs amplification, frequency conversion, etc.; 15 is an antenna; and 16 is a communication line modulation/demodulation unit that modulates and demodulates signals transmitted and received on the communication line 5.

Reference numeral 20 denotes a standby earth station (hereinafter referred to as a backup station) that performs communication and monitoring control in place of the master station when a failure occurs in the master station, and 22 to 26 are respectively installed in the master station 10. These are the same supervisory control line modulation/demodulation unit, supervisory control unit, transmitting/receiving unit, antenna, and communication line modulation/demodulation unit as those shown in the figure. Further, 30 is an earth station that communicates with the master station 10 and is monitored and controlled by the master station 10, and here, a portable station is taken as an example. Note that 4 is a communication satellite.

FIG. 8 shows the system configuration when the master station 10 is performing communication and monitoring control, and FIG. 9 shows the system configuration when the backup station 20 is performing communication and monitoring control. It is something.

Next, the operation will be explained. In the system configuration shown in FIG. 8, the master station 10 communicates with the portable station 30 and monitors and controls the backup station 20 and the portable station 30. That is, the communication line 5 (frequency f1 and f
2) to communicate with the portable station 30. Also, using the monitoring line 6 (frequency f3 and f4), the mobile station 30
In addition to specifying lines and setting terminal constants for the station, the backup station 20 is also monitored. Of the monitoring lines 6, the downlink (frequency f3) from the master station 10 is called a control line, and the uplink (frequency f4) is called a monitoring line.

On the other hand, the backup station 20 is in a standby state so that it can immediately perform the master station function when the earth station function failure occurs in the master station 10 due to a disaster or the like. Backup station 20 is normally unmanned. Then, when a failure occurs in the master station 10, the operator at the master station 10 abandons the master station 10 and moves to the backup station 20. Then, an operation is performed to exchange the roles of the master station 10 and the backup station 20.

[0007] The operation is performed in the following steps. First, the backup station 20 uses the monitoring line to
Sends a replacement request signal to 0. Monitoring control unit 1 of master station 10
3 receives the replacement request signal via the antenna 15, the transmitter/receiver 14, and the supervisory control line modulator/demodulator 12, the supervisory controller 13 stops the transmission carrier of the communication line modulator/demodulator 16. It also sends a replacement request response signal to the supervisory control line modulation/demodulation section 12 . The supervisory control line modulation/demodulation section 12 returns the carrier modulated with this replacement request response signal to the backup station 20 using the control line.

When the backup station 20 receives the replacement request response signal, it sets itself as the master station. As a result, the system configuration becomes as shown in FIG. 9, and the communication line modulation/demodulation section 26 starts transmitting the transmission carrier. Further, the supervisory control unit 23 includes a supervisory control line modulation/demodulation unit 22, a transmitting/receiving unit 24,
, sends a backup station setting signal to the original master station 10 via the antenna 25 and the supervisory control line 6. When the original master station 10 receives the backup station setting signal, it sets its own station as the backup station. In the manner described above, the roles of the master station and the backup station have been exchanged.

[0009] The above processing is carried out by both monitoring control units 13 and 2.
However, if role switching becomes impossible for some reason, the backup station 20 manually sets the master station. However, in this case, there are two master stations.

0010

[Problem to be Solved by the Invention] Since the conventional satellite communication system is configured as described above, when an attempt is made to execute a role change, if an abnormality occurs in the supervisory control section 13, a change request is issued. Unable to receive the signal, the master station 10 remains in the state of sending out the transmission carrier. Therefore, in order for the backup station 20 to communicate with the portable station 30, the frequency of the communication line must be changed, and extra frequencies (channels) must be secured in advance in case of failure. There was an issue. Incidentally, there is a prior art disclosed in Japanese Patent Laid-Open No. 61-232727.

[0011] This invention was made to solve the above-mentioned problem, and the transmitting carrier of the master station cannot be stopped according to instructions from the backup station due to reasons such as the failure of the supervisory control section of the master station. An object of the present invention is to provide a satellite communication system that can resume communication with an earth station such as a portable station without changing the frequency of a communication line even in the case of a mobile station.

0012

[Means for Solving the Problems] The satellite communication system according to the invention as set forth in claim 1 provides a method for transmitting communication signals to a master station upon detecting a carrier disconnection command via a communication line from an earth station such as a backup station or a portable station. This system is equipped with a communication line modulation/demodulation section that stops signal transmission to the line.

[0013] In addition to the configuration of the system according to the invention as claimed in claim 1, the satellite communication system according to the invention as claimed in claim 2 also provides a backup station with interference that disturbs the frequency used for the communication line. A communication line modulation/demodulation unit is provided with an interference wave sending unit that sends out waves, and when an earth station such as a portable station detects that the interference wave is present in the communication line, it sends a carrier disconnection request signal to the master station. It has been established.

[0014] In the satellite communication system according to the third aspect of the invention, the backup station is provided with an interference wave transmitter for transmitting interference waves that interfere with the frequency used for the communication line, and the master station is provided with: This system is equipped with a communication line modulation/demodulation section that stops transmitting signals to the communication line when it detects the presence of the interference wave on the communication line.

[0015]

[Operation] The communication line modulation/demodulation section of the master station according to the invention as claimed in claim 1 stops the transmitting carrier in response to a carrier disconnection request command, and prevents the transmitting carrier from being transmitted when a failure occurs in the monitoring control section of the master station. This enables smooth role switching between the master station and backup station.

[0016] Furthermore, the backup station in the invention as claimed in claim 2 transmits an interference wave to the communication line at the time of role change, and sends a carrier disconnection request signal to the communication line to the earth station such as a portable station. Notify you of what to report.

[0017] When the communication line modulation/demodulation section of the master station in the invention according to claim 3 detects the presence of interference waves transmitted from the backup station in the communication line, it stops the transmission carrier, and the master station monitors the communication line. To enable smooth role switching between a master station and a backup station even if a failure occurs in a controlling part.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a master station, 2 is a backup station,
Reference numeral 3 denotes a portable station having a communication line modulation/demodulation section 31 capable of transmitting a carrier disconnection request signal. In the master station 1, 11 is a communication line modulation/demodulation section that stops transmitting carriers when a carrier disconnection request signal is detected. In this case, in the backup station 2, the communication line modem unit 2
1 also serves as an interference wave transmitting section. Other parts are the same as those shown in FIG. 8 with the same reference numerals. Note that FIG. 1 shows a situation where a failure occurs in the master station 1 and a role change is required, but the conventional role change sequence cannot be completed due to a failure of the supervisory control unit 13 or the like.

Next, the operation will be explained. Assume that the operator has moved to backup station 2 due to the need for a role change. Due to a failure of the supervisory control unit 13 of the master station 1, etc., the transmission carrier (frequency f1) sent from the master station 1 to the communication line 5 as in the conventional case is changed to a supervisory control line (not shown). It is assumed that it is impossible to use the system to stop the system. Therefore, even if the backup station 2 starts transmitting a transmission carrier of frequency f1, it collides with the transmission carrier transmitted by the master station 1, so communication between the backup station 2 and the portable station 3 is impossible.

Therefore, the communication line modulation/demodulation section 21 of the backup station 2 uses an unmodulated carrier (frequency f1) of a higher level than the normal modulated carrier flowing through the communication line 5.
Send out.

The communication line modulation/demodulation section 31 of the mobile station 3 is configured as shown in FIG. 2, for example. Here, the signal received by the antenna 35 of the mobile station 3 is converted into an intermediate frequency (IF) signal by a transmitter/receiver (not shown), and the IF distributor 3
7. IF distributor 37 outputs an IF signal including a signal corresponding to frequency f1 to demodulator 39A and level abnormality detection circuit 38.

In the level abnormality detection circuit 38, the bandpass filter 381 limits the band of the IF signal to the vicinity of the signal corresponding to the frequency f1. Then, the output level of the bandpass filter 381 is detected by a level detection circuit 382. The determination circuit 383 determines whether the detection level of the level detection circuit 382 is
It is determined whether the level is the level when there is no unmodulated carrier or the level when it is added, and if it is determined that the unmodulated carrier is added, a notification signal is sent to the modulator 39B.

The modulator 39B adds a carrier disconnection request signal to the game warning slot in the data transmitted to the master station 1 in response to the notification signal. The transmission data is sent to the master station 1 and the backup station 2 via the communication line 5 of frequency f2.

When the communication line modem units 11 and 21 of the master station 1 and the backup station 2 detect the carrier disconnection request signal, they immediately stop transmitting the carrier at frequency f1. Since the backup station 2 already has an operator, the backup station 2 is manually set as the master station. and,
The backup station 2, which has become the master station, communicates with the portable station 3 using the communication line 5 with frequencies f1 and f2.

Note that in the above embodiment, the backup station 2
We have explained the case where the portable station 3 sends out an unmodulated wave with a frequency of f1 and the portable station 3 detects a level abnormality, but as shown in FIG. 3, the interference wave sent out by the backup station 2 has a frequency of f1.
The modulated wave 71 may be the same. In FIG. 3, 70 indicates a transmission wave of frequency f1 from the master station 1. In FIG.

Further, as shown in FIG. 4, the interference wave may be an unmodulated wave 72 with a frequency f11 that is shifted from the frequency f1 but within the communication frequency band, or as shown in FIG. The modulated wave 73 having the frequency f11 may be used. However, in those cases, in the mobile station 3, the bandpass filter 381 and the level detection circuit 382 of the level abnormality detection circuit 38 adapt to the frequency f11 or appropriately change the threshold level for abnormality determination. It has become a thing.

FIG. 6 shows the communication line modulation/demodulation section 11 of the master station 1A.
This shows the case where A is provided with a part for detecting level abnormalities. The communication line modulation/demodulation section 11A is configured as shown in FIG. 7, for example.

In this case, the backup station 2A sends out an unmodulated carrier of frequency f2. The signal received by the antenna 15 of the master station 1A is converted into an intermediate frequency (IF) signal by the transmitting/receiving section 14 and supplied to the IF distributor 17. The IF distributor 17 sends the IF signal including the signal corresponding to the frequency f2 to the demodulator 19A and the level detection circuit 1.
Output to 8.

In the level abnormality detection circuit 18, the bandpass filter 181 limits the band of the IF signal to the vicinity of the signal corresponding to the frequency f2. Then, the output level of the bandpass filter 181 is detected by a level detection circuit 182. The determination circuit 183 determines whether the detection level of the level detection circuit 182 is the level when there is no unmodulated carrier or the level when the unmodulated carrier is added, and if it is determined that the unmodulated carrier is added, Sends a stop signal to Then, the modulator 19B stops transmitting the transmission carrier in response to the stop signal.

[0030] Also in the above embodiment, the interference waves include a modulated wave of frequency f2, a modulated wave of frequency f22 (f2 and f22
have a similar relationship to the relationship between f1 and f11. ) or a modulated wave of frequency f22 can be used.

[0031]

As described above, according to the invention set forth in claim 1, the satellite communication system can be connected to a communication line by a master station in response to a carrier disconnection command received from an earth station such as a portable station or a backup station. Since the configuration is such that the signal transmission of the master station is stopped, even if there is an abnormality in the supervisory control section of the master station, the signal transmission of the master station can be reliably stopped, and role switching can be performed smoothly.
This has the effect of eliminating the need to prepare a spare line for communication.

According to the second aspect of the invention, the satellite communication system is configured such that an earth station such as a portable station that detects the interference wave sent out by the backup station sends a carrier disconnection signal to the parent station. As a result, even if there is an abnormality in the supervisory control unit of the master station, the signal transmission of the master station can be reliably stopped, roles can be changed smoothly, and there is no need to prepare a spare line for communication. It has the effect of

According to the third aspect of the invention, the satellite communication system is configured so that the communication line modulation/demodulation section of the master station that detects the interference wave sent out by the backup station stops sending out signals to the communication line. Because of this configuration, even if there is an abnormality in the monitoring control section of the master station, signal transmission can be reliably and promptly stopped, roles can be changed smoothly and quickly, and it is necessary to prepare a spare line for communication. It has the effect of giving you something you don't have.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing a satellite communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a communication line modulation/demodulation section of the mobile station.

FIG. 3 is a spectrum diagram showing an example of the relationship between transmission waves from a master station and interference waves from a backup station.

FIG. 4 is a spectrum diagram showing another example of the relationship between transmission waves from a master station and interference waves from a backup station.

FIG. 5 is a spectrum diagram showing still another example of the relationship between the transmission wave of the new station and the interference wave of the backup station.

FIG. 6 is a system configuration diagram showing a satellite communication system according to another embodiment of the present invention.

FIG. 7 is a block diagram showing a communication line modulation/demodulation section of the master station.

FIG. 8 is a system configuration diagram showing a conventional satellite communication system (before role change).

FIG. 9 is a system configuration diagram showing a conventional satellite communication system (after role switching).

[Explanation of symbols]

1　　　　　Master station 2 Backup station 3 Portable station 11 Modulation/demodulation section for communication line 11A Modulation/demodulation section for communication line 17 IF distributor 18 Level abnormality detection circuit 181 Bandpass filter 182 Level detection circuit 183 Judgment circuit 19A Demodulator 19B Modulation section 21 Modulation/demodulation section for communication line 31 Modulation/demodulation section for communication line 37 IF distributor 38 Level abnormality detection circuit 381 Bandpass filter 382 Level detection circuit 383 Judgment circuit 39A Demodulation section 39B Modulation section

Claims (3)

[Claims] Claim 1: An abnormality occurs in a supervisory control earth station that performs communication and supervisory control, an earth station that communicates with the supervisory control earth station using a communication line via a communication satellite, and the supervisory control earth station. In the satellite communication system, the satellite communication system includes a standby earth station that performs communication and monitoring control on behalf of the monitoring and controlling earth station when the monitoring and controlling earth station is connected to the communication line from the earth station or the standby earth station. A satellite communication system comprising: a communication line modulation/demodulation unit that stops transmitting signals to the communication line when a carrier disconnection command is received via the communication line. 2. The standby earth station includes an interference wave transmitter that transmits an interference wave that interferes with a frequency used in a communication line, and the earth station is configured to detect the presence of the interference wave on the communication line. 2. The satellite communication system according to claim 1, further comprising a communication line modulation/demodulation section that sends a carrier disconnection request signal as a carrier disconnection command to the monitoring control earth station when detecting the carrier disconnection command. 3. An abnormality occurs in a supervisory control earth station that performs communication and supervisory control, an earth station that communicates with the supervisory control earth station using a communication line via a communication satellite, and the supervisory control earth station. In the satellite communication system, the standby earth station is equipped with a standby earth station that performs communication and monitoring control on behalf of the monitoring and control earth station, in which case the standby earth station is equipped with an interference wave that interferes with the frequency used for the communication line. The supervisory control station includes a communication line modulation/demodulation unit that stops transmitting a signal to the communication line when detecting the presence of the interference wave on the communication line. A satellite communication system characterized by: