FR2506480A1 - Call transmission arrangement e.g. for elderly - uses radiating network with telephone lines radio links and local two-wire connections for monitored terminals - Google Patents

Abstract

The monitoring system includes e.g. two groups of four terminals, although it may be extended to include more. The terminals may be installed in the homes of e.g. elderly people, and are linked to a checking circuit within the group. The checking circuit may be positioned in a cellar or attic, and is connected to the terminals in its group by pairs of wires for telephone type transmission. The checking circuit is then linked to a local 'concentrating' control by a radio link. The local control may communicate with up to eight checking circuits by arranging these at angular separations of 45 degrees. Each concentrating control then communicates with a central station by a special telephone line. The system enables permanent monitoring of a large number of vulnerable terminals.

Description

 The present invention relates to a call transmission system comprising a network of subscriber boxes and a central station.

 Such systems find their application today for example in the protection of citizens against theft, or assistance to the sick and elderly, subscribers of these systems.

 In systems known to date, calls can be transmitted from subscriber boxes to the central station, either from manual triggering by keyboard, or automatically from a burglar detector.

 These systems use the switched telephone network as the transmission medium.

 However, the use of ordinary telephone lines is the source of two disadvantages of these systems.

 First of all, the necessity of having ordinary telephone lines is in itself a constraint. Then, and above all, these systems are unilateral systems, with which it is not possible to verify the establishment of the connections between the subscriber boxes and the central station.

 The present invention therefore aims to overcome these constraints by proposing a system which does not use the switched telephone network, and which allows permanent verification of all terminations.

 To this end, the present invention relates to a call transmission system, comprising a network of subscriber boxes and a central station, characterized in that the connection between each subscriber box and the central station is established by by means of three independent scanning loops having respectively as transmission media a pair of wires, a radio link and a dedicated telephone line.

 In a preferred embodiment of the system of the invention, each subscriber unit is connected to a scanner by a pair of wires, each scanner is connected to a concentrator by radio link, and each concentrator is connected to the central station by dedicated telephone line.

The system of the invention does not use the switched telephone network, it has great flexibility of use and extension. In addition, all terminations can be checked continuously by the question and answer set.
The invention will be better understood with the aid of the following description of a preferred embodiment of the system of the invention, with reference to the appended drawing, in which
- Figure l shows an overview of the system of the invention, with its three scanning loops
FIG. 2 represents a schematic block diagram of the connecting members of a scanner or a concentrator of the system of FIG. t, and
FIG. 3 represents a block diagram of the connecting members of a scanner and of a subscriber unit of the system of FIG. 1.

 The system shown in Figure 1 has two groups 1 and 2 of four subscriber boxes 11,12,13,14 and 21,22,23,24. Of course, the system could comprise more than two of these groups or only one, and each of these groups could comprise more than four of these boxes or only one. Overall, the system could handle several hundred or even several thousand subscribers. These boxes are installed in private homes, the sick or the elderly, for example.

The boxes of each group 1,2 are connected to a scrutineer 3,4, for example placed in a cellar, attic or similar place of a building or group of buildings, and distant from the boxes by a distance of up to 1 km .

The connection between the boxes of a group and their associated scrutineer is carried out by respective pairs of wires, for a telegraphic type transmission. The scanners 3 and 4 are connected to a concentrator 5 by microwave radio channels. Each concentrator in the system can be connected to eight scanners angularly spaced 450 from each other. The system could include at least a few hundred concentrators. Finally, the concentrator 5 is connected to a central station 6 by a dedicated telephone line.

 Thus, the connection between each subscriber unit and the central station is established by means of three independent scanning loops, unit-scanner, scanner-concentrator and-concentrator-central station.

 The central station 6, which it is not necessary to describe in detail since it is as a whole already known elsewhere in conventional call transmission systems, comprises in particular a microcomputer 61, a terminal comprising a screen 62 for viewing the state of the system and a control keyboard 63, a printer 64 for recording any change in state of the system, a buzzer, in a block 67, for hearing calls from subscriber boxes, and a transmitter 65, for possible connection with an intervention team 66. In any case, the central station 6 is connected to a series of services, such as social assistance, police, fire or emergency services block 67.

 The connection between each scanner and its associated concentrator is made by two radio channels, one for the scanner-concentrator direction and another for the opposite concentrator-scanner direction. Transmission takes place at microwave frequencies, for example around 9.9 GHz, corresponding to a radar type transmission. Such a radio link allows jumps of two hundred meters and avoids having to fire cabals.

 The transmission between the scanner and the concentrator is preferably carried out according to the "half duplex half-duplex call-response" mode.

 Thus, each scanner 3,4 is, in the example considered, associated (FIG. 2) with a set 100 comprising an asynchronous universal transceiver unit 7, provided with a current generator and receiving logic signals, unit which is connected to an isolation interface 8, itself connected to two transmission elements 9 and reception 10, respectively arranged to transmit and receive signals at microwave frequencies, for example at 9.9 GHz more or less 30 kHz.

 Each set of transmit-receive 100 of a scanner corresponds to the same set 100 at the level of the concentrator 5 (FIG. 1). The latter is therefore equipped with two of these assemblies 100, since the system shown comprises two scanners 3,4.

 Still by way of example and with regard to the logic signals of the units 7 mentioned above, at the frequency 9.9 GHz + 30 kHz corresponds the logic level 1 and at the frequency 9.9 GHz - 30 kHz corresponds the level 0.

 The transmission between the box and the scanner preferably takes place in the "half-duplex simplex call-response mode", and at a speed of 1200 baud.

 Thus, each scanner, for example the scanner 3 shown in FIG. 3, preferably comprises a microprocessor, not shown, a transmitting photocoupler 31, a receiving photocoupler 33, the two photocouplers 31,33 being connected in parallel on the pair of transmission wires 101 connecting the scanner 3 to a group 1 subscriber unit, for example the unit 11 in FIG. 3, and a current generator 32 for supplying the line 101.

The box 11, like each of the subscriber boxes, preferably comprises, in the same way, a receiving photocoupler 111 and a transmitting photocoupler 112, the two photocouplers being connected in parallel to the pair of wires 101. A Zener diode 113 is connected to the terminals of the receiving photocoupler 111 to eliminate the
scrutineer.

noises and parasites. It is the same for that of /
The transmission of information between the scrutineer and the relevant box is carried out as follows
When a message is sent by the scrutineer to the box, the emission photocoupler 31 of the scrutineer, controlled by the microprocessor of the scrutineer, becomes on, i.e. closes, and short-circuits line 101 , and this, at the rate of the bits of the message. The message is received beyond line 101 by the receiving photocoupler 111 of the box, its transmitting photocoupler being blocked, i.e. open. When a message is sent by the box to the scrutineer, the transmission photocoupler 112 of the box closes and short-circuits the line 101, the message being received by the reception photocoupler 33 of the scanner, its transmission photocoupler 31 being open.

 It should be noted that the closing of an emission photocoupler effectively causes a short circuit of the line 101, therefore a voltage drop which in turn causes a drop in the line current, and it is this drop in current which is detected by the associated receiving photocoupler and placed at the other end of the transmission line 101.

 Note, moreover, that each scanner is supplied by the network, but that there are advantageously provided backup batteries. Furthermore, each box is supplied with current from a battery disposed in the associated scanner and by means of a unilateral pair of remote supply wires drawn between this box and its scanner.

 The call transmission system described above, thanks to its three types of independent transmission or scanning loops, allows permanent verification of all terminations. It is a system operating in digital, with the exception of radio loops.

 Apart from the particular modes of transmission discussed above, the system functions like conventional systems. However, any scanning mode can be developed indifferently given the flexibility of the system. But, as we have already seen above, the call-response mode is preferred to the others.

Claims (8)

REVENDI CATIONS  1. Call transmission system, comprising a network of subscriber boxes and a central station, characterized in that the connection between each subscriber box and the central station is established by means of three independent loops of polling having respectively as transmission media a pair of wires, a radio link and a dedicated telephone line.  2. The system as claimed in claim 1, in which each subscriber unit is connected to a scanner by a pair of wires, each scanner is connected to a concentrator by radio link, and each concentrator is connected to the central station by dedicated telephone line. .  3. The system of claim 2, wherein each concentrator is connected to eight scanners angularly spaced 450 from each other.  4. System according to one of claims 2 and 3, wherein the connection between each scanner and its associated concentrator is effected by two radio channels.  5. The system as claimed in claim 4, in which the transmission between the scanner and the concentrator takes place by the half-duplex half-duplex call-response mode.  6. System according to one of claims 2 to 5, in which the transmission between the scanner and the subscriber unit takes place by the call-response mode in the half-duplex on the simplex line.  7. The system as claimed in claim 6, in which the subscriber boxes and their associated scanners each comprise a transmit photocoupler and a receive photocoupler connected in parallel to the corresponding pair of wires.  8. System according to one of claims 2 to 7, in which each subscriber unit is supplied with current from a battery disposed in the associated scanner and by a unilateral pair of remote supply wires.