JPH01181248A - Demand assign communication system - Google Patents

Abstract

PURPOSE:To decrease the physical quantity of the device and to attain inexpensive constitution by adopting a control sequence in a manner of sharing a modulator/demodulator for a common control signal line with that for traffic. CONSTITUTION:A modulator/demodulator 2 acts like a modulator/demodulator for a common signal control line and a transmission reception carrier is set to a frequency fCSC by a control line 9. Then after the signal is received, the transmission/reception carrier frequencies of slave stations A, B are set to frequency f1, f2 by the control line 9. A voice channel is set between both the slave stations in this state and in case of the termination of the call, the line is released between exchanges of both the salve stations in a route of signal interface 7 controller 3 signal interface 8 modulator/demodulator 2 and the call is terminated between telephone sets.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a demand assignment communication system that is often used in satellite communication systems.

[Conventional technology]

Figure 2 shows the demand assign satellite communication system, where 11 is the master station and demand assign (hereinafter referred to as DAM) is the master station.
This is the earth station that centrally controls the system (referred to as A), and is also called the parent DAMA station. 12 is a slave station,
It is an earth station that is responsible for the traffic of n stations, and from the perspective of DAMA control, it is in the position of requesting the master station 11 to set up a line, and is also called a child DAMA station. 13 indicates a satellite. Figure 3 shows an example of frequency allocation used in the DAMA system in Figure 2, where 14 is a common signal control line (C
ommon Signaling Channel
), and all stations making up the system are required to be able to transmit and receive this carrier wave. 1
5 indicates L pairs (t is an integer of 1 or more) of two carrier waves each, and for example, one bidirectional line is supplied by fl and f2. Such a carrier wave pair is set up by a command from the master station each time a request for line connection from a slave station to the master station is made, and is canceled when it is no longer needed. FIG. 4 shows a configuration diagram of the slave station. In the figure, 1 is a transmitter/receiver connected to an antenna. 3 is a DAMA control device of the slave station, 4 is an exchange, 5 is a telephone or equivalent, 6 is a telephone band channel signal, 7 is a signal (signaling) interface with the exchange, 8 is an interface with the modem 17 9 is a signal line for specifying the determined carrier frequency to the modulator/demodulator 16; 10 is an intermediate frequency interface serving as an interface with the transmitter/receiver; 16 is a modulator/demodulator for communication path; This is a modulator/demodulator for common signal control lines.

Next, the operation will be explained. FIG. 5 shows the operating procedure of this system, where 18 is, for example, the frequency fl shown in FIG. 3, and 19 to 21 are frequencies fe! Ie, 22 indicates information carried by frequency f2, and information 18.19 indicates one of the slave stations (station A), 2
1.22 is the slave station of the other party of station A (referred to as station B) and 2
0 relates to the master station.

First, it is assumed that a call request is made from the A-side telephone. A
The exchange 4 of the station transmits this to the DAMA control device 3 of the station A through the signal interface 7t, which drives the modem 17 using the signal interface B and sends the connection request 23 to the other station as shown in FIG. It is transmitted to the master station along with the number. The master station selects an unused pair (for example, fl and t2) from the available carrier waves 15 and sets the frequency f. Message 24.2 to stations A and B via 3c
Convey 5. Generally, at this stage, complicated procedures such as confirmation responses to eliminate connection errors may be added between the slave station and the master station, but these are not essential and will therefore be omitted here. Furthermore, as can be seen from the above, since both the master station and slave stations share the same carrier and transmission, the access method generally uses TDMA, random access, or a combination thereof. Since these are not related to the essence of the present invention, their explanation will be omitted.

Now, the modem 1T of each slave station receives these commands,
The DAMA control device 3 is notified of the allocated carrier wave from the master station. As a result, a bidirectional line is established between the ph station and the B station using the carrier waves fl and fz, and a call can be started. This is indicated by symbol 28 in FIG. When the call ends, a call termination signal (signaling) is output from the exchange 4, and the DAMA control unit @3 sends a line release request to the master station via the same route as when making the connection request, this time at 29t - frequency f Ole. request. An acknowledgment response of 30 is sent from the master station to the slave station.
Release instruction 31 is issued to slave station B, and at signal 32.33,
The DAMA control device 3 of each station sends necessary call termination processing signals 32, 3 . ．． 3 and the frequency'*
s fz t-cut. The DAM controller 3 of the naori station sends a release confirmation signal 34t to the master station.

In FIG. 5, the solid line on the vertical axis indicates that the carrier wave is being transmitted or is virtually occupied, and the dotted line indicates that the carrier wave is not being used and can be used by other stations.

[Problem to be solved by the invention]

As is clear from the sequence in Figure 5, in the conventional example, one modulator/demodulator is required for the common signal control line and one (or more) modulator/demodulator for the communication path, which is especially true for small-scale stations. In stations where only one channel to several channels are required, there is a problem in that the physical amount of equipment increases.

This invention was made to solve the above-mentioned problems, and its purpose is to reduce the cost and simplify the construction of small-scale stations.

[Means to solve the problem]

In this invention, the carrier frequency of the modulator and demodulator is switched between when a connection is made and when a call is made so that one modulator and demodulator can be used for a common signal control line and a communication path.

[Effect]

When connected, the carrier wave of the modulator/demodulator is assigned to the common signal control line signal 9, and when a call is made, it is assigned to the opposing slave station.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

In FIG. 1, reference numeral 2 denotes a modulator/demodulator for a common signal control line/communication path. The other parts are the same as the device and function described in FIG. 4.

FIG. 6 is a diagram showing the connection control sequence.

Next, the operation will be explained with reference to FIGS. 1 and 6.

The flow up to symbols 23, 24, 25, 26, and 27 in FIG. 6 is the same as in FIG. The transmission/reception carrier wave is controlled by the control line 9 at a frequency fe.
s(! However, signals 26 and 2
After receiving 7, it becomes slave station A.

The transmitting/receiving carrier wave frequencies of the modulator/demodulator B are similarly set to frequencies f1 and fz by the control line 9, and communication with the master station via the common signal control line is no longer possible. In this state, a voice communication path circuit 28 is established between the probe stations, and a communication path is established between the telephones of both slave stations. To end a call, a line release operation is performed directly between the exchanges of the two slave stations via the signal interface T -> control device 3 -> signal interface 8 -> modulator/demodulator 2, and the call is ended between the telephones. DAMA control unit R3 can monitor this, so
When both slave stations confirm the end of the call using signal 35, the DAMA control devices 3 of both slave stations automatically cut off frequencies fl and fz, and set the frequency of the modem to frequency f. Perform the action to return to BQ. After that, as in FIG. 5, the parent DAMA station is notified that the line has been released and can be used by other stations.

Incidentally, in the above embodiment, the configuration of the station is shown in which only one voice communication path is required. FIG. 7 shows another embodiment in which two voice communication paths are required. In this case, the same thing as above can be achieved by providing the switch 36 so that the communication signal with the master station is transmitted only to the modulator/demodulator used as the common signal control line. This switch is naturally controlled by the -DAMA control device 3.

This concept can be easily applied to the case where three or more channels of voice communication paths are provided, and the same effect can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, since a control sequence is adopted in which the modulator/demodulator for the common control signal line can be shared with that for traffic, the physical amount of the device is reduced and the device can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a slave station according to an embodiment of the present invention, and FIG.
The figure is a DAMA system configuration diagram, Figure 3 is a diagram showing an example of carrier wave arrangement in the DAMA system, Figure 4 is a diagram showing the configuration of a slave station according to the conventional example, and Figure 5 is a series of sequences for connection and release of lines according to the conventional example. FIG. 6 is a diagram showing a series of line connection and release sequences according to another embodiment, and FIG. 7 is a configuration diagram of a slave station according to another embodiment. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. 1...Transmitter/receiver, 2...modulator/demodulator, 3...
Control device, 4...exchange, 5...telephone, 16
．． 17...Modulator/demodulator.

Claims (1)

[Claims] Consisting of a parent and child station and a plurality of slave stations, common signal line control is performed by each station in the system sharing a wave, and the actual communication path is controlled by the parent and child stations in the system in response to a communication path connection request. In the demand assignment communication method, which uses a carrier wave that is determined each time according to instructions from the station, when controlling the line connection, the carrier frequency of the modem is controlled to be the carrier wave for the common line, and after the line is set up. This is a demand assignment communication system characterized in that the carrier frequency of a modulator/demodulator is controlled to be a carrier wave for a communication line determined by a command from a master station.