JP2616594B2 - Reception level information transfer method for mobile satellite communication system. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile satellite communication system, and more particularly to a system for transmitting reception level information at a central station.

[0002]

2. Description of the Related Art A mobile satellite communication system is composed of a small number of central stations and a large number of slave stations communicating therewith. In particular, the number of slave stations accommodated in the system is very large as compared with the conventional satellite communication system. It is a big feature that there are many. For example, Inmarsat (International Maritime Satelli
A system called te Organization = Inmarsat) -C stipulates that the Pacific Ocean, Atlantic Ocean, and Indian Ocean each accommodate up to 10,000 ship earth stations (child stations).
On the other hand, as a characteristic of the satellite communication system, since the satellite transponder is shared by a large number of participating stations, there is a risk that a failure in the transmission signal of only one earth station will adversely affect the entire communication system. For example, interference with other signals due to fluctuations in the transmission frequency or transmission at an excessive transmission level affects the operating point of the satellite transponder, and the nonlinearity degrades the line quality of all other signals. Such,
Because there is a risk of adversely affecting the communication of many other stations,
Transmission signals need to be strictly regulated.

[0003] Therefore, when there is a newly participating earth station, an earth station apparatus having a performance sufficient for performing an adaptation test to determine whether or not its performance is suitable for the system and participating. It must be confirmed that in mobile satellite communication systems, the number of stations participating in the system is very large,
It is important to complete the performance tests of the earth stations that are participating one after another without delay. For this reason, the central station incorporates an automatic measurement function for performing a conformity test.

As described above, one of the conformity test items includes confirmation of the transmission level of the slave station. To measure the transmission level of the slave station at the central station, measure the reception level when the signal is received from the slave station via a communication satellite, and indirectly compare this with the known signal level. A method of measuring is generally used. For this reason, as shown in FIG. 3, in the conventional central station device, the modem 1 receives the received signal 11 and demodulates and outputs the received data 12, while the reception level measuring device 2 outputs the demodulated signal from the modem 1. Received signal 1
1 was input, the reception level was measured, and this was output as reception level information 13.

[0005]

By the way, the central station is:
Functionally, it is divided into a satellite communication transceiver unit, a satellite communication modem unit, and a satellite line control unit that controls them. In recent years, in configuring a mobile satellite communication system, a system in which a satellite channel control unit in a central station is installed in a network control station that controls the entire satellite communication system, and a modem unit and a transmission / reception unit configure the central station. Has been proposed. Such a system has many advantages, such as a streamlined configuration of the control system devices, since all control systems are integrated in the network control station. Therefore, the number of cases to be introduced in the future is increasing.

However, in such a system, as described above, when the reception level information from the slave station measured by the modem is transferred from each modem individually to the satellite line controller, the data is received separately from the line of the received data. There is a problem that a line for transferring the level information is required, the number of lines becomes extremely large, and it is economically disadvantageous. SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer method which enables transfer of reception level information without increasing the number of lines between a modem unit and a line control unit.

[0007]

According to the present invention, there is provided a transfer system comprising:
Consists of a heart station and many slave stations, and has a satellite line system in the central station
Network system that controls the entire satellite communication system
Installed at your own station, and the central station is composed of the modem / transmitter / receiver.
That in the mobile satellite communications system, the central station, reception
A modem that demodulates the signal and outputs the received data;
Reception level measuring device that measures reception level information from signals
And time division multiplexes the reception data and reception level information
And a time division multiplexer, the central station, said demodulates the data transmitted from the slave station modem unit network
At the time of transfer to the control station , reception data obtained by demodulating a reception signal and reception level information measured from the reception signal are time-division multiplexed and transferred.

[0008]

According to the present invention, the reception level information is time-division multiplexed and transferred to the reception data, so that there is no need to independently provide a line for transferring the reception level information.

[0009]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a reception level information transfer method according to the present invention. In FIG. 1, a modem 1 demodulates received data 12 from an input received signal 11 and outputs the demodulated data to a time division multiplexer 3. At the same time, the modulator / demodulator 1 sends a part of the reception signal 11 to a reception level measuring device 2 which measures the reception level. The reception level measuring device 2 measures the reception level value and outputs it to the time division multiplexer 3 as reception level information 13. In the time division multiplexer 3, the reception data 12 and the reception level information 13 are time division multiplexed,
And output from an output terminal.

Therefore, in this reception level information transfer system, both the reception data 12 and the reception level information 13 are multiplexed into the multiplexed signal 1 through the output terminal for outputting the reception data 12.
4 can be output simultaneously. Therefore, it is not necessary to independently provide an output terminal for transferring the reception level information, and it is not necessary to provide a line for transferring the reception level information between the modem and the line controller.

[0011]

As described above, according to the present invention, the reception data obtained by demodulating the reception signal and the reception level information measured from the reception signal are time-division multiplexed, and the multiplexed signal is transmitted from the modem to the line controller. Since the transfer is performed, there is no need to separately provide a line for transferring the reception level information between them, and there is an effect that an increase in the number of lines is prevented and an economically effective transfer can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a reception level information transfer method according to the present invention.

FIG. 2 is a diagram of a time division multiplex format for transmitting reception level information.

FIG. 3 is a block diagram of an example of a conventional reception level information transfer method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Modulator / demodulator 2 Reception level measuring device 3 Time division multiplexer 11 Reception signal 12 Reception data 13 Reception level information 14 Multiplex signal

Claims (1)

(57) [Claims] 1. A consists center station and a plurality of slave stations, the central
The satellite link control unit in the station controls the entire satellite communication system
Installed in a network control station,
In the mobile satellite communication system constituting the central station by
The central station demodulates the received signal and outputs the received data
Modem that measures the received level information from the received signal.
A reception level measuring device, and the reception data and reception level information.
And a division multiplexer time-division multiplexing during the broadcast, the central station, before demodulates the data transmitted from the slave station modem unit
Receiving a demodulated received signal and receiving level information measured from the received signal in a time-division multiplexing manner when transferring the received signal to a network control station ; method.