Note: Descriptions are shown in the official language in which they were submitted.
CA 02264854 1999-03-02W0 98/10529 PCT/EP97/04528TITLE OF THE INVENTIONGlobal telecommunication, monitoring and telesignallingnetworkBACKGROUND OF THE INVENTIONThe present invention relates to a telecommunicationnetwork, and in particular it relates to atelecommunication, monitoring and telesignalling network.For quite a time it has been asserted the need ofdevelopping systems which guarantee to citizens a timelyassistance in answer to the most common emergencyrequirements, e.g. sanitary, public order emergencies orconnected to accidental events as fires or floodings.Furthermore it is always more pressing the demand for a moreefficient management of the public transport, of the privatetraffic, and in general for a better accessibility to thebasic services from both citizens and visitors of our towns.By modern technologies is has become finally accessiblewhat in past was merely theoretical, that is to think to beable to provide the important urban centres, and graduallythe entire territory, with a telecommunications network thatcan perform a lot of the above exposed needs. Howeverremained a great problem in the real difficulty ofinserting, in the complex structure of the towns, a networkwith such a capacity and such a capillarity to satisfyentirely said needs, without going towards enormous costsand as much enormous adaptation works.CA 02264854 1999-03-02wo 98/10529 PCT/EP97/04528In the Italian patent application N.TO96A0OOl83 isdescribed a signaling system that overcomes the difficultyof providing a communication network by utilizing, in amanner so to say âparasiteâ, the preexisting urban lightingnetwork and the respective electric lines. The datatransmission takes place in a practically unidirectionalmanner, if it is excepted the possibility of theconfirmation that the transmission from the portabletransmitter took place. The data transmission on theelectrical network by means of peripheral units, located oneach light point of the lighting network, to the receptionexchanges, located in the substations for distributing theelectrical energy to the single street lamps, takes place byusing conveyed waves transmission methods, such as, forexample, modulated frequencies on carrier frequency.A system so conceived presents however some drawbacks.Firstly, there is not a concrete possibility of acommunication between the network and the user possesing theremote device, so that the user, apart a simple signal ofreceived message, do not know how and in how many time hisdemand will be performed; further it is not provided thepossibility" of furnishing information to the xgser throughthe network, beyond the emergency situations. Secondly, theuse of a data transmission on the network by conveyed wavespresents considerable practical difficulties for itsapplication.In fact, the emitted signal must have a certain power inorder to obtain an appreciable result, there is the risk ofCA 02264854 1999-03-02W0 98/10529 PCT/EP97l04528-3-noises, as beats with systems of the kind of AM transmissionor wire broadcasting, thus with the need of verification,for each cable used, of the pass band and of the possibleinterference with other signals. Furthermore, thetransmission and the data reception speed between theperipheral terminals and the reception exchanges is ratherrestricted.In the Italian patent application RM96AOOOl16 a datatransmission system is described also making use of thestreet lighting network; said system however do not foreseethe use of mobile terminals, and is articulated into threelevels, that is supervision level, control level, and fieldstations level. The data transmission between the peripheralunits and the control level takes place by the emission ofnot modulated tones, which permits a data stream of greaterdimensions with respect to the previously described system.However such communication is based on the assumption thateach peripheral unit of the network be in turn intocommunication with the exchange, thus denying thepossibility of a reaction to a plurality of simultaneouscalls. Further each peripheral unit sends with its message,its identification code, with the consequent consumption ofavailable characters.SUMMARY OF THE INVENTIONScope of the present invention is to provide acommunication network which is able to overcome the abovedescribed drawbacks, by allowing a bidirectionalcommunication between mobile terminal and network, and atCA 02264854 1999-03-02wo 9s/10529 PCT/EP97/04528-4-the same time providing said network with a datatransmission system which is less influenced. by possibleinterferences, and which allows a greater data stream alongthe network by the use of reduced power.Object of the present invention is therefore atelecommunication, monitoring and telesignalling network,characterised by the fact that said network comprises:â a plurality of mobile receivingâtransmitting terminals;â a plurality of pick up elements, each one being able to beconnected to the said mobile terminals, each pick up elementbeing disposed in correspondence of 21 light point of thepublic lighting installation connected to said installation,and provided with means for the transmission and thereception through the lines of said public lightinginstallation; andâ a plurality of control units connected to said lightinginstallation, which are capable to be connected to said pickup elements, each control unit being disposed in adistribution substation of said lighting installation, andbeing connected to the plurality of pick up elements locatedon the light points connected to said substation, eachcontrol unit being provided with means for the reception andthe transmission of data to and from an operative exchange.BRIEF DESCRIPTION OF THE DRAWINGSFurther advantages and features will be evident from thefollowing dettailed description of one embodiment ofâ thepresent invention made, by way of non limiting example, withreference to the annexed drawings, in which:CA 02264854 1999-03-02wo 98/10529 PCT/EP97/04528...5_Figure 1. is a schematic perspective view of atelecommunication network according to the presentinvention;Figure 12 is a schematic diagram showing a network pickup element according to the invention;Figure 3 is a schematic diagram showing a networkcontrol unit according to the invention; andFigure 4 is a diagram representing an oscillation cycleof the tension of the public lighting network.DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTIONIn Figure 1. a telecommunication network according thepresent invention is shown; with 1 the mobile receiving andtransmitting terminal is designed. Said terminal 1 comprisesa processing unit 101, a transmitting group 201 and areceiving group 201. Said terminal is able to communicatewith the pick up element 2 disposed on the pole ll of thestreet lamp 10 and connected to the cable 21 which feeds thelamp 12 of the street lamp 10, and which in turn isconnected. to the urban lighting installation line 20. Asknown, in an urban lighting installation a shunt substationis provided for any given light point number, controllingtheir power supply. In the Figure, in the shunt substation30 the control unit 3 is inserted in parallel with theswitch 31 of the said substation, same being connectedthrough the connecting means 41, which in the following willbe better described and illustrated, to the operativeCA 02264854 1999-03-02WO 98/10529 PCT/EP97/04528station 40.In Figure 2 a diagram is shown schematically showing apick up element 2 of the net according to the invention.Same comprises a processing unit 102 provided with a feeder112 connected through the wire 122 to the cable 21 of thestreet lamp 10. To the processor 102 a radio interface 202is connected, to which the transmitting group 212 and thereceiving group 222 respectively provided with antennas 232and 242 are connected. likewise to the processor 102 thetransmitter 312 and the receiver 322 are connected, which inturn are connected through the respective wires 332, 342 tothe wire 122 coupled to the cable 21 of the street lamp 10.In Figure 3 a diagram is shown showing a network controlunit 3 of the network according to the invention. Said unitcomprises a processor 103 connected to the street lightinginstallation line 20 through a feeder 113. To the processor103 the transmitting group 213 and the receiving group 223are connected; both said groups are finally connected to theline 20. To the processor is further connected the tensionshutter 303, the mode of operation of which will bedescribed later. As last, the processor is provided with aconnection with an interface 403 communicating with theconnecting means 41 for the connection with operativestation 40.In Figure 4 is finally shown diagrammatically thesinusoid which represents the tension oscillation of thepublic lighting network. In abscissa the diagram has timeCA 02264854 1999-03-02wo 93/10529 PCT/EP97/04528__'7...values in seconds and in ordinate tension values. As it maybe seen the diagram is subdivided into 10 subperiods, ofwhich two subperiods 23 are wider in correspondence with themaximum and minimum values of the single obscillation, and 8subperiods which are equal each other.The operation of the communication network according tothe invention will be evident from the following. The mobileterminal 1 shown in Figure 1 permits to the user 50 to senda signal 401 through his transmitting unit 201, containingthe aid request and other possible data processed ormemorized in processor 101 of the terminal 1. The signal maybe received by the pick up element 2 placed on pole 11 ofthe street lamp 10. Once received the signal 401, the pickup element 2 will send it to the control unit 3.In the prior art devices of the kinda described, thetranfert of the data from the peripheral unit, similar tothe pick up element of the invention, to the communicationnetwork takes place by the use of conveyed wave transmissionsystems, which presents the already mentioned drawbacks. Inthe network according to the invention said transfert isperformed by a system which faces the problem in a quite newand innovative way. The starting assumption is based on thefact that every single pick up element is connected to thenetwork and synchronized on the network frequency, that is50 Hz. Thus the wave presents 50 cycles during the space ofone second, that is 20 milliseconds (msec) per cycle. Thesignal modulation means 302 of the pick up elements dividefurthermore each cycle (see Figure 4) into ten subcycles, ofCA 02264854 1999- 03 - 02W0 98/10529 PCT/EP97/04528-8-which the two wider cycles 23 in correspondence of themaximum and minimum points of the obscillation are not takeninto consideration. In this manner eight subcycles 24 of 1,5msec each remain. The single pick up element sends in eachsubcycle a tone, emitted in a range comprised for examplewithin 2 and 4 kHz and characteristic of a single pick upelement, where the tone presence shows that a signal bit hasbeen dispatched at a logical level 1, and thus that in a 20msec space, that is 21 complete obscillation cycle of thenetwork feeding tension, a signal containing eight data bit,that is a character (byte) may be dispatched. Then in onesecond only the pick up element may transmit 50 bytes ofdata.The different pick up elements have each acharacteristic emission tone, and the emission frequencydifference between adjacent pick up elements is tipically inthe range of 20 Hz, which is an extremely small value,however sufficient because the tone bandwidth is practicallyof null value. Thanks to this last characteristic it is verydifficult that this kind of data transmission be subject tointerferences.In order that the control unit be able to distinguishthe different messages sent by different pick up elementsconnected to it (for example 100 pick up elements for a samecontrol unit) it must have a Digital Signal Processingdevice (DSP). Assuming as frequency distance between pick upelement and pick up element a frequency of 20 Hz as abovereferred, the DSP has to distinguish between the differentCA 02264854 1999-03-02W0 98/10529 PCT/EP97/04528_.9_signals on a total band of 2 kHz. Advantageusly, therecognizing of each pick up element by the control unit cantake place in this manner through their emission tones, witha significative character saving, because no identificationdata have to be sent. A further advantage of the datatransmission by tones at the frequencies in the ranges abovementioned, resides in the use of an extremely limited poweron-all the network.The datum aquired from the control unit, and containingthe information of the position of the calling terminal, aswell as those relating to the kind of requested service, isthereafter conveyed, through suitable connecting means, asfor example a transmission made with the aid of a satelliteor 21 connection âvia optical waveguides, to the operativestation, where the datum will be collected and decoded andfrom where the answer~ to the user's requirement will beforwarded.A further problem for a communication network using thelines of a street lighting installation is that during theday the street lamps are off, and is not desirable to keepthem on both because of the great electric energy wastewhich will come from, and because of the impossibility ofdoing the normal maintenance. The control unit 3 comprises atension shutter device 303 which has the duty, whenever theswitch 31 of the cabin 30 is opened, to deliverâ a lowvoltage, in the range of 40-50 V, in alternating current at50 Hz, on the length of line 20 connected to the differentstreet lamps, so as to guarantee both the feeding and theCA 02264854 1999-03-02wo 98/10529 PCT/EP97/04528_]_O_.transmission of the pick up elements placed on street lamps.As soon as the switch 31 is again closed, the shutter 303will be automatically cut out.The thus conceived telecommunication network permits tothe user to receive informations and to transmittinformations by the same network; at the same time, thanksto the transmission system used in the communication betweenpick up elements and control unit, the data flow is greaterthen that which may be achievable by known systems, incorrespondence with a greater practicality of use and minorsignal noise possibilities.
