AU713026B2 - Global telecommunication, monitoring and telesignalling network - Google Patents

Description

WO 98/10529 PCT/EP97/04528 TITLE OF THE INVENTION Global telecommunication, monitoring and telesignalling network BACKGROUND OF THE INVENTION The present invention relates to a telecommunication network, and in particular it relates to a telecommunication, monitoring and telesignalling network.

For quite a time it has been asserted the need of developping systems which guarantee to citizens a timely assistance in answer to the most common emergency requirements, e.g. sanitary, public order emergencies or connected to accidental events as fires or floodings.

Furthermore it is always more pressing the demand for a more efficient management of the public transport, of the private traffic, and in general for a better accessibility to the basic services from both citizens and visitors of our towns.

By modern technologies is has become finally accessible what in past was merely theoretical, that is to think to be able to provide the important urban centres, and gradually the entire territory, with a telecommunications network that can perform a lot of the above exposed needs. However remained a great problem in the real difficulty of inserting, in the complex structure of the towns, a network with such a capacity and such a capillarity to satisfy entirely said needs, without going towards enormous costs and as much enormous adaptation works.

I I WO 98/10529 PCT/EP97/04528 -2- In the Italian patent application N.T096A000183 is described a signaling system that overcomes the difficulty of providing a communication network by utilizing, in a manner so to say "parasite", the preexisting urban lighting network and the respective electric lines. The data transmission takes place in a practically unidirectional manner, if it is excepted the possibility of the confirmation that the transmission from the portable transmitter took place. The data transmission on the electrical network by means of peripheral units, located on each light point of the lighting network, to the reception exchanges, located in the substations for distributing the electrical energy to the single street lamps, takes place by using conveyed waves transmission methods, such as, for example, modulated frequencies on carrier frequency.

A system so conceived presents however some drawbacks.

Firstly, there is not a concrete possibility of a communication between the network and the user possesing the remote device, so that the user, apart a simple signal of received message, do not know how and in how many time his demand will be performed; further it is not provided the possibility of furnishing information to the user through the network, beyond the emergency situations. Secondly, the use of a data transmission on the network by conveyed waves presents considerable practical difficulties for its application.

In fact, the emitted signal must have a certain power in order to obtain an appreciable result, there is the risk of noises, as beats with systems of the kind of AM transmission or wire broadcasting, thus with the need of verification, for each cable used, of the pass band and of the possible interference with other signals. Furthermore, the transmission and the data reception speed between the peripheral terminals and the reception exchanges is rather restricted.

In the Italian patent application RM96AO00116 a data transmission system is described also making use of the street lighting network; said system however do not foresee the use of mobile terminals, and is articulated into three levels, that is supervision level, control level, and field stations level. The data transmission between the peripheral units and the control level takes place by the emission of not modulated tones, which permits a data stream of greater dimensions with respect to the previously described system.

However such communication is based on the assumption that each peripheral unit of the network be in turn into communication with the exchange, thus denying the possibility of a reaction to a plurality of simultaneous calls. Further each peripheral unit sends with its message, its identification code, with the consequent consumption of available characters.

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-4- An object of the present invention is to provide a communication network which may alleviate the above described drawbacks. The present invention may allow bidirectional communication between mobile terminal and network, and at the same time may provide the network with a data transmission system which is less influenced by possible interferences, and which allows a greater data stream along the network by the use of reduced power.

According to the present invention there is provided telecommunication, monitoring and telesignalling network, said network including: a plurality of mobile signal receiving and transmitting terminals; a plurality of pick up elements, each terminal being adapted to be connected to said mobile terminals, each pick up element being disposed in a position which corresponds to a light point of a public lighting installation, and being connected to said installation and provided with means for transmitting and 15 receiving signals through lines of said public lighting installation; and i a plurality of control units connected to said lighting installation, said control units being adapted to be connected to said pick up elements, each control unit being placed in a distribution substation of said lighting installation, and being connected with the pick up elements disposed on the light points 20 connected to said substation, each control unit being provided with means for transmitting and receiving data to and from an operative station.

A preferred embodiment of the present invention will now be described with reference to the annexed drawings, in which: MJP C:\WINWORD\MARIE\GABNODEL\42995CL.DOC WO 98/10529 PCT/EP97/04528 Figure 1 is a schematic perspective view of a telecommunication network according to the present invention; Figure 2 is a schematic diagram showing a network pick up element according to the invention; Figure 3 is a schematic diagram showing a network control unit according to the invention; and Figure 4 is a diagram representing an oscillation cycle of the tension of the public lighting network.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION In Figure 1 a telecommunication network according the present invention is shown; with 1. the mobile receiving and transmitting terminal is designed. Said terminal 1 comprises a Processing unit 101, a transmitting group 201 and a receiving group 201.. Said terminal is able to communicate with the pick up element 2 disposed on the pole .1 of the street lamp 10 and connected to the cable 21 which feeds the lamp 12 of the street lamp 10, and which in turn is connected to the urban lighting installation line 20. As known, in an urban lighting installation a shunt substation is provided for any given light point number, controlling their power supply. In the Figure, in the shunt substation the control unit 3 is inserted in parallel with the switch 31 of the said substation, same being connected through the connecting means 41, which in the following will be better described and illustrated, to the operative j WO 98/10529 PCT/EP97/04528 -6station In Figure 2 a diagram is shown schematically showing a pick up element 2 of the net according to the invention.

Same comprises a processing unit 102 provided with a feeder 112 connected through the wire 122 to the cable 21 of the street lamp 10. To the processor 102 a radio interface 202 is connected, to which the transmitting group 212 and the receiving group 222 respectively provided with antennas 232 and 242 are connected. Likewise to the processor 102 the transmitter 312 and the receiver 322 are connected, which in turn are connected through the respective wires 332, 342 to the wire 122 coupled to the cable 21 of the street lamp In Figure 3 a diagram is shown showing a network control unit 3 of the network according to the invention. Said unit comprises a processor 103 connected to the street lighting installation line 20 through a feeder 113. To the processor 103 the transmitting group 213 and the receiving group 223 are connected; both said groups are finally connected to the line 20. To the processor is further connected the tension shutter 303, the mode of operation of which will be described later. As last, the processor is provided with a connection with an interface 403 communicating with the connecting means 41 for the connection with operative station In Figure 4 is finally shown diagrammatically the sinusoid which represents the tension oscillation of the Public lighting network. In abscissa the diagram has time WO 98/10529 PCT/EP97/04528 -7values in seconds and in ordinate tension values. As it may be seen the diagram is subdivided into 10 subperiods, of which two subperiods 23 are wider in correspondence with the maximum and minimum values of the single obscillation, and 8 subperiods which are equal each other.

The operation of the communication network according to the invention will be evident from the following. The mobile terminal 1 shown in Figure 1 permits to the user 50 to send a signal 401 through his transmitting unit 201, containing the aid request and other possible data processed or memorized in processor 101 of the terminal 1. The signal may be received by the pick up element 2 placed on pole 11 of the street lamp 10. Once received the signal 401, the pick up element 2 will send it to the control unit 3.

In the prior art devices of the kind described, the tranfert of the data from the peripheral unit, similar to the pick up element of the invention, to the communication network takes place by the use of conveyed wave transmission systems, which presents the already mentioned drawbacks. In the network according to the invention said transfert is performed by a system which faces the problem in a quite new and innovative way. The starting assumption is based on the fact that every single pick up element is connected to the network and synchronized on the network frequency, that is Hz. Thus the wave presents 50 cycles during the space of one second, that is 20 milliseconds (msec) per cycle. The signal modulation means 302 of the pick up elements divide furthermore each cycle (see Figure 4) into ten subcycles, of WO 98/10529 PCT/EP97/04528 -8which the two wider cycles 23 in correspondence of the maximum and minimum points of the obscillation are not taken into consideration. In this manner eight subcycles 24 of msec each remain. The single pick up element sends in each subcycle a tone, emitted in a range comprised for example within 2 and 4 kHz and characteristic of a single pick up element, where the tone presence shows that a signal bit has been dispatched at a logical level I, and thus that in a msec space, that is a complete obscillation cycle of the network feeding tension, a signal containing eight data bit, that is a character (byte) may be dispatched. Then in one second only the pick up element may transmit 50 bytes of data.

The different pick up elements have each a characteristic emission tone, and the emission frequency difference between adjacent pick up elements is tipically in the range of 20 Hz, which is an extremely small value, however sufficient because the tone bandwidth is practically of null value. Thanks to this last characteristic it is very difficult that this kind of data transmission be subject to interferences.

In order that the control unit be able to distinguish the different messages sent by different pick up elements connected to it (for example 100 pick up elements for a same control unit) it must have a Digital Signal Processing device (DSP). Assuming as frequency distance between pick up element and pick up element a frequency of 20 Hz as above referred, the DSP has to distinguish between the different WO 98/10529 PCT/EP97/04528 -9signals on a total band of 2 kHz. Advantageusly, the recognizing of each pick up element by the control unit can take place in this manner through their emission tones, with a significative character saving, because no identification data have to be sent. A further advantage of the data transmission by tones at the frequencies in the ranges above mentioned, resides in the use of an extremely limited power on all the network.

The datum aquired from the control unit, and containing the information of the position of the calling terminal, as well as those relating to the kind of requested service, is thereafter conveyed, through suitable connecting means, as for example a transmission made with the aid of a satellite or a connection via optical waveguides, to the operative station, where the datum will be collected and decoded and from where the answer to the user's requirement will be forwarded.

A further problem for a communication network using the lines of a street lighting installation is that during the day the street lamps are off, and is not desirable to keep them on both because of the great electric energy waste which will come from, and because of the impossibility of doing the normal maintenance. The control unit 3 comprises a tension shutter device 303 which has the duty, whenever the switch 31 of the cabin 30 is opened, to deliver a low voltage, in the range of 40-50 V, in alternating current at Hz, on the length of line 20 connected to the different street lamps, so as to guarantee both the feeding and the WO 98/10529 PCT/EP97/04528 transmission of the pick up elements placed on street lamps.

As soon as the switch 31 is again closed, the shutter 303 will be automatically cut out.

The thus conceived telecommunication network permits to the user to receive informations and to transmitt informations by the same network; at the same time, thanks to the transmission system used in the communication between pick up elements and control unit, the data flow is greater then that which may be achievable by known systems, in correspondence with a greater practicality of use and minor signal noise possibilities.

Claims (10)

1. Telecommunication, monitoring and telesignalling network, said network including: a plurality of mobile signal receiving and transmitting terminals; a plurality of pick up elements, each terminal being adapted to be connected to said mobile terminals, each pick up element being disposed in a position which corresponds to a light point of a public lighting installation, and being connected to said installation and provided with means for transmitting and receiving signals through lines of said public lighting installation; and a plurality of control units connected to said lighting installation, said control units being adapted to be connected to said pick up elements, each control unit being placed in a distribution substation of said lighting installation, and being connected with the pick up elements disposed on the light points 9connected to said substation, each control unit being provided with means for S: 15 transmitting and receiving data to and from an operative station.

2. Network according to Claim 1 wherein each said pick up element includes: a processor provided with feeding means connected to a feeding line of said lighting installation; means for receiving and transmitting signals to and from 20 said mobile terminal; means for transmitting and receiving signals to and from said control unit, all connected to said feeding line of the installation and to said processor through means for modulating and demodulating said signal. 9

3. Network according to claim 2, wherein said signal modulation means includes: means for subdividing each oscillation cycle of current of the feeding line of the public lighting installation into ten subcycles, two of said subcycles corresponding to the maximum and minimum values of said oscillation and not being taken into consideration, whilst the remaining eight subcycles correspond to eight bits of a character of the datum to be transmitted; means for emitting a tone with a frequency substantially between 500 and 5000 Hz for each bit having a logical level equal to 1, the difference in frequency between the tones of two contiguous pick up elements being substantially between 20 and 50 Hz. MJP C:\WINWORD\MARIE\GABNODEL\4295CL.DOC -12-

4. Network according to claim 2 or 3, wherein each said control unit includes: a processor connected through a feeder to said feeding line of said public lighting installation; a transmitter and a receiver connected to said feeding line and connected to said processor through a digital signal processing device.

Network according to claim 4, wherein said digital signal processing device includes means to distinguish, in a frequency band from substantially 1 to 2 kHz, the tones emitted by each pick up element connected to said control unit.

6. Network according to any one of the preceding claims wherein said control unit is connected, in the distribution substation of said lighting installation, in parallel with switch means which control ignition of the light points connected to said substation and is provided with a tension shutter device which, at any time 15 that the switch means are opened, consents to delivery to the light points of a low tension voltage, in the range of substantially 40 to 50 V, at the same frequency as the network tension, said shutter being automatically cut out from the circuit whenever said switch means are shut off. 9 C

7. Network according to any one of claims 3 to 6, wherein said tones are delivered at a frequency range substantially between 2000 and 4000 Hz. C. I

8. Network according to any one of claims 3 to 7, wherein the tone frequency difference between the tones of two contiguous pick up elements is substantially 20 Hz.

9. Telecommunication, monitoring and telesignalling network substantially as herein described with reference to the accompanying drawings. DATED:

10 September, 1999 PHILLIPS ORMONDE FITZPATRICK Attorneys for: SCITYCOM S.p.A.