FR2745672A1 - Communication device for alarm signal transmission - Google Patents

Abstract

The device includes a communication network which has a subscriber installation with multiple service units (1) which send consumer information to distributors via a network (2). The multiple service units can be used for example by electricity and gas providers. An alarm system (3) is connected into the service network. Each service unit contains a modem which transmits call signals using SFSK signals and a modem which transmits alarm signals using FSK signals. The frequency band used by the FSK modem is between the two frequencies used by the SFSK modem. A computer controller ensures automatic communication.

Description

 The present invention relates to the communication of electricity and / or gas subscribers with the distributing administration and relates more particularly to the communication between a multiservice unit installed in the premises of a subscriber and a call concentrator .

 As part of the development of interactive communications between subscribers and the energy distributor, a multiservice box or terminal installed at a subscriber's place enables the subscriber to receive statements of his electricity or gas consumption by means of telecommunications connected to the multi-service terminal.

 It also allows the distributor to read the subscriber's meters by simply interrogating the multiservice terminal.

 It also makes it easy to detect subscribers whose power or gas has been cut.

 However, the network of multiservice terminals of subscribers interconnected with a central agency of the distributor requires providing security means of high efficiency but of an acceptable cost price.

 The invention relates to a new technique for transmitting alarm signals on a carrier transmission medium.

It therefore relates to a communication device for the transmission of alarm and call signals from subscriber installations to a distributor agency, characterized in that it comprises multiservice boxes associated with the meters placed at the subscribers and an alarm and call communication automaton placed on the distribution network of said subscribers in communication with said multiservice boxes by the carrier current technique and in that each multiservice box includes a modem for transmitting signal signals call in S-FSK modulation and a modem for transmitting alarm signals in FSK modulation, the frequency band used by the FSK modem being inserted between the two frequencies used by the S-FSK modem, control and initiative modulation
S-FSK being provided by the communication automaton while the management of access to the FSK modulation is provided by multiservice boxes.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the accompanying drawings, in which
- Fig.1 is a block diagram of a communication device for the transmission of alarm signals according to the invention;
- Fig.2 is a graph of a frequency spectrum illustrating the simultaneous use of the S-FSK and FSK modulations in the same frequency band and allowing the implementation of the device of Figure 1;
- Fig.3 is a block diagram of the signal transmission circuit associated with a multiservice box;
- Fig.4 is a more detailed block diagram showing the frequency separation circuit and coupling to the distribution circuit; and
- Fig.5 is a block diagram of the separator circuit used in the construction of the separation circuit of Figure 4.

 The block diagram of FIG. 1 represents a communication device according to the invention which comprises multiservice boxes 1 connected to a network 2, for example an electrical current distribution network.

 The multiservice boxes are connected to a call concentrator 3 also connected to the network 2 to which is also connected a dedicated alarm repeater 4 intended to receive the alarm signals received from the multiservice boxes 1 and to re-emit them to the concentrator 3.

 This device operates in the following manner.

 A question-answer type protocol which corresponds to a hardware configuration "1 master to n slaves n implementing the current principle of carrier current links on public distribution network, makes it difficult to immediately transmit alarm signals spontaneously emitted by slave equipment.

 For this purpose, a different communication channel must be provided, permanently accessible to slave stations for the immediate transmission of their alarm signals.

 The coordinated use in the same frequency band of two different modulation techniques, namely the S-FSK and FSK modulations makes it possible, according to the rules which will be described below, to effectively create such a communication channel.

 The S-FSK modulation consists in transmitting a signal on two frequencies for example on 60 kHz and 74 kHz, by transmitting on one of the frequencies the signal itself and on the other its complement.

 A natural redundancy is thus obtained which allows for example to choose for reception, the frequency for which the best signal / noise ratio is obtained.

 The S-FSK modulation is characterized, among other things, by a narrow mask between each nominal frequency.

 The arrangement of the alarm signal transmission channel consists of inserting between these two frequencies a band modulated in FSK modulation.

 For this purpose, a carrier frequency of 66 kHz is chosen with a frequency hopping of 4 kHz maximum, which makes it possible to transmit signals at a speed of 2400 Bauds, so that the transmission frequencies are 62 and 70 kHz and do not overlap the frequencies modulated in S-FSK.

 The diagram in Figure 2 illustrates this solution.

 This mode of transmission optimizes the physical coupling mode according to the principle of the filter coupler which is the subject of French patent No. 91 12 821.

 The central channel 2 of the device in FIG. 1 benefits from the highest network impedance and a maximum gain in the transfer of energy over the network.

 This alarm signal transmission channel is used to carry the report information of the protocol standardized by CIETC 57, 1334-4-41, ie DLMS.

 The management of multiple access to this channel modulated in FSK can be carried out by means of a conventional carrier detection protocol.

 For example, each station comprising a multiservice box 1 waits to transmit, that line 2 is free (no carrier) for a period proportional to its MAC address, which ensures uniqueness at all times of the attempts to access the support. .

 In order to increase the transmission range on the distribution network, if necessary, a repeater such as the repeater 4 dedicated to the frequency concerned and to the type of message to be transmitted is placed on the electrical distribution network.

 This equipment listens to the network in search of an alarm message.

 As soon as a message is received, the repeater 4 reproduces it on line 2.

 The communication channel thus formed is unidirectional.

 The alarm station cannot therefore receive the acknowledgment of receipt of this message.

 An acknowledgment should therefore be made on the normal channel modulated in S-FSK.

 This acknowledgment provided by the distribution automaton takes the form of a normal reading on the channel modulated according to S-FSK of the registers of the data link layer associated with the information transfer service (the alarm) in the box. multiservice issuer, in order to keep total accounts with the existing (standards and products).

 The alarm must be repeated until the alarm recipient has read it.

 It is then possible to define the emergency levels (service parameter) for the messages conveyed by the network, levels which govern the frequency of re-emission of the alarm.

 The following classification can be considered.

0 - no repetition (routine message or conversation maintenance)
1 - repetition every 10 minutes
2 - repetition every minute
3 - repetition every 10 seconds
The use of the value 0 for the absence of repetition allows to maintain compatibility with the MAC layer of the IEC standard (parameter, class of service).

 On the other hand, the use of the other values already assigned to the use of short frames, requires the drafting of a normative appendix associated with the DLMS standard (or a derogation from its use).

The transmission of alarm signals is ensured by the circuits shown in
Figs. 3 to 5 which will now be described.

 The circuit shown in FIG. 3 includes a separator circuit 5 connected upstream to a counter 6 connected via the mains to the call concentrator 3 and downstream to a circuit breaker 7.

The separator 5 is also connected to a switch 8, by means of a switch 8a, the input of which is connected to five output lines of the separator circuit 5 and which has a two-wire output connected to a modem S -FSK 9, a two-wire output connected to a modem
ASK 10 and two two-wire outputs for FSK alarm and home automation signals connected respectively to the fixed terminals of switch 8, the mobile terminal of this switch being connected to a FSK 11 modem.

 The modems 9,10,11 are in turn connected to a central unit 12 of the multiservice unit with which the device is associated. Finally, a two-wire output from the switch 8a is connected to a supply circuit 13.

 The FSK 11 modem has a first operating frequency whose value is for example 132.5 kHz for the transmission of home automation signals in the subscriber circuit and a second operating frequency whose value is for example 66 kHz for the transmission of alarm signals.

Call concentrator 3 has an S modem
FSK 14 for the reception and transmission of normal call signals relating to the management and interrogation of multiservice boxes 1 of the network it manages and a demodulator FSK 15 for the reception of alarm signals from modems FSK 11 of multiservice boxes, the alarm signals being assigned the appropriate level of emergency.

 The circuit of FIG. 4 which is in fact the separation circuit 5 associated with the circuit breaker 7 provided with its trip button 7a, connected between phase and sector neutral, comprises an intelligent module 20 which is a central unit associated with a modem ASK 20a, itself connected to a separator circuit 22 which receives its power supply from the mains, taken upstream of the circuit breaker 7. It also receives the S-FSK signals via a filter coupler 23 on a line 24 , while the FSK alarm signals are derived from a supply line 25 with the interposition of a capacitor 26.

 The filter coupler circuit 23 is a circuit of the type described in the aforementioned invention patent No. 91 12 821, filed on October 17, 1991 by the Applicant.

 It is in fact a directional separator-coupler for carrier currents at medium frequency on an electrical line of the low-voltage alternating network comprising a parallel resonant circuit inserted on the electrical line, the resonance frequency of which is close to the central frequency of the passband of the carrier currents and a transmission-reception circuit of said carrier currents coupled in voltage to said resonant circuit by a connection circuit.

 The connection circuit also comprises a series connection branch making it possible to ensure current coupling of the transmitter-receiver circuit and the medium frequency line and a decoupling of said transmission-reception circuit of the line at the frequency of the low network. voltage.

 The separation circuit is also connected to the output of the circuit breaker 7 by a line 26 for transmitting home automation carrier currents with FSK modulation. Thus, the separation circuit 22 ensures the separation of the various modulation signals S-FSK, FSK and ASK which pass over the lines of the network.

 A line 28 connects the intelligent module 20 and more particularly its ASK modem 20a to the counter 6.

 The separation circuit finally comprises a line 28 for connection with a multiservice box, certain elements of which such as the modems 9, 10 and 11 and the central unit 12 are described with reference to FIG. 3.

 This line 29 in fact comprises a line 29a for transmitting the PLC, SFSK, FSK alarm and supply signals and a line 29b for transmitting the FSK home automation signals and the ASK signals.

 The separator circuit 22 will now be described in more detail with reference to FIG. 5.

 It is produced on the basis of a phantom circuit commonly used in telephony and includes six transformers 30 to 35 wound on ferrite cores with a small number of turns adapted to the frequency of the signals to be transmitted.

 The transformer 30 is connected to the output for the S-FSK signals of the filter coupler 23.

 At one of the terminals of the winding 30a of the transformer 30 is connected a decoupling capacitor 36.

 The winding 30b of the transformer 30 is connected by a first twisted line 38 to the terminals of the winding 33a of the transformer 33, the winding 33b of which is intended to be connected to the means for receiving and receiving signals S-FSK from the multiservice box (not shown) corresponding.

 The winding 31a of the transformer 31 is connected to the power sector via a decoupling capacitor 26 (Fig.4).

 It is intended to transmit FSK modulated alarm signals from the corresponding multiservice unit.

 Its winding 31b is connected on the one hand to the midpoint of the winding 30b of the transformer 30 and on the other hand, to the midpoint of the winding 32b of the transformer 32 for signal transmission n Euridis in ASK modulation of consumption readings counters.

 The winding 32a of the transformer 32 is connected to the ASK modem 20a of the intelligent module 20.

 The winding 32b of the transformer 32 is connected by a second twisted line 42 to the winding 35a of the transformer 35, the winding 35b of which is connected to the meter reading control means 6 contained in the multiservice unit (not shown).

 The first and second twisted lines 38, 42 are advantageously twisted together in order to avoid mutual parasitic couplings of the various signals transmitted.

 The midpoint of the winding 31b of the transformer 31 for transmitting the FSK modulated alarm signals is connected to a terminal of the secondary winding of a supply transformer 44 with a laminated core connected to the sector to which is also connected l winding 31a of transformer 31.

 The other terminal of the secondary winding of the transformer 44 is connected to ground.

 In parallel on the secondary winding of the transformer 44 is connected a capacitor 46 in series with a winding 48b of a transformer 48 with a core formed of a ferrite core, whose winding 48a is connected to the network downstream of the circuit breaker 7 for the transmission of home automation signals with FSK modulation.

 The ground of the transformer 44 is connected to the ground of a transformer 52 supplying the multiservice unit by a line 50 which forms an additional line for signal transmission by means of an isolation of the circuits from earth, permitted by the low supply voltage, for example 24 V, required by the multiservice unit.

 The transformer 52 is also a transformer with a laminated core.

 Its primary winding is connected between earth and the midpoint of the winding 34a of the transformer 34 for transmitting the FSK alarm signals, one of the terminals of the winding 34a being connected to the midpoint of the winding 33a of the transformer 33 for connecting the S-FSK signals with the multiservice unit, while its other terminal is connected to the midpoint of the winding 35a of the transformer 35 for transmitting ASK meter reading signals to the multiservice unit.

 In parallel on the primary winding of the transformer 52 are connected in series a winding 54b of a transformer 54 with a ferrite core core and a capacitor 56. The winding 54a of the transformer 54 is connected to the transmission-reception means of FSK modulation home automation signals from the multiservice box.

 The arrangement which has just been described with reference to FIG. 5 has an additional transmission channel by taking advantage of the fact that the telephone cables generally used to produce the phantom circuits from which the separator circuit derives for the most part a ground wire.

 It is therefore possible to superimpose on a phantom circuit a supply circuit and an additional transmission channel materialized by the line 50.

 In the present application, the frequency of the phantom circuit is 20 times higher than in telephony, so that the components used are simpler and therefore much less expensive than at low frequency.

 The transmission circuit according to the invention does not require adjustment.

 The ferrite toroids of transformers 30 to 35, 48 and 54 do not pose an insulation problem.

 In fact, their windings may not be superimposed whereas a conventional transformer with superimposed windings requires protection means.

 The circuit of Figure 5 finally has the advantage of being indifferent to the transmitted frequencies whose bands can be changed in significant proportions.

Claims (13)

CLAIM  1. Communication device for the transmission of alarm and call signals from subscriber installations to a distributor agency, characterized in that it comprises multiservice boxes (1) associated with the meters placed at subscribers' and an automaton (3) for communication of alarms and calls placed on the distribution network (2) of said subscribers in communication with said multiservice boxes (1) by the carrier current technique and in that each multiservice box (1 ) comprises a modem (14) for transmitting call signals in modulation S-FSK and a modem (16) for transmitting alarm signals in modulation FSK, the frequency band used by the FSK modem being inserted between the two frequencies used by the S-FSK modem, the control and the initiative of the S-FSK modulation being ensured by the communication automaton while the management of access to FSK modulation is provided by multiservice boxes (1).  2. Communication device according to claim 1, characterized in that it further comprises on the central channel (2) of the link distribution network of multiservice boxes (1) with the communication automaton (3) a repeater ( 4) dedicated to the frequency of alarm signals in FSK modulation.  3. Communication device according to one of claims 1 and 2, characterized in that it comprises, associated with each counter (6), circuit breaker (7) subscriber assembly, a separator (5) of the various modulation signals transmitted on the distribution network (2), said separator (5) being connected to a central unit (12) of the multiservice unit (1) corresponding by an S-FSK modem (9) for the call signals and by an FSK modem (11) for alarm signals.  4. -Communication device according to claim 3, characterized in that the separator (5) is connected to the FSK modem (11) for the alarm signals via a switch (8a) and a switch (8) between a mode of transmission of domestic signals in the multiservice unit and the mode of transmission of alarm signals to the communication automaton (3).  5. Communication device according to one of claims 3 and 4, characterized in that the separator (5) is further connected to the central unit (12) by an ASK modem (10) for the meter reading signals .  6. Communication device according to one of claims 3 to 5, characterized in that the splitter (5) comprises a central unit (20) connected to the subscriber circuit breaker (7), a circuit for splitting modulation signals (22 ) connected by a first line (24) to a filter coupler (23) connected to the network between the counter (6) and the circuit breaker (7) and intended to transmit the call signals in S-FSK modulation to the separating circuit, and by a second line (25) directly to the distribution sector (2) upstream of said filter coupler (23), said separator circuit (22) being further connected to the distribution network (2) downstream of the circuit breaker, by a third line (26) for transmitting FSK modulation home automation signals.  7. Communication circuit breaker according to claim 6, characterized in that the central unit (20) comprises an ASK modem (20a) for the meter reading signals and in that the connecting line of the central unit (20 ) with the separator circuit (22) is further connected by a line (29) to the associated counter (6).  8. Communication device according to one of claims 1 to 7, characterized in that the communication automaton (3) comprises a modem (14) for the signals S-FSK and an FSK-modulated alarm signal demodulator (15).  9. Communication device according to one of claims 3 to 5, characterized in that the separator circuit (22) comprises means with transformers (30,33) and with line (38) for transmitting modulated call signals S-FSK, transformer means (31,34,48,54) for transmitting alarm and home automation signals in FSK modulation associated with transformer means (44,52) and a transmission line (50) of the supply voltage of the associated multiservice unit, from the sector and means with transformers (32,35) and line (42) for transmission of ASK modulation meter reading signals.  10. Communication device according to claim 9, characterized in that the transformers (30 to 35, 48,54) of the means for transmitting signals S FSK, FSK and ASK are transformers with a ferrite core.  11. Communication device according to one of claims 9 and 10, characterized in that the transmission lines of the S modulated call signals FSK and ASK modulated meter reading signals are lines that are twisted separately and then twisted together.  12. Communication device according to one of claims 9 to 11, characterized in that the line (50) for transmitting the supply voltage to the multiservice unit also ensures the transmission of alarm and home automation signals with FSK modulation. .  13. Communication device according to claim 12, characterized in that the means for transmitting alarm and domotics signals with FSK modulation comprise a first transformer (31) with ferrite core having a first winding (31a) is connected to the mains and a second winding (31b) of which is connected to the midpoints of corresponding second windings (30b, 32b) of first transformers (30,32) with ferrite core cores of the means for transmitting the call signals and meter reading with S-FSK and ASK modulation, said second winding (31b) of the first transformer (31) being connected on the one hand, to the secondary winding of a supply transformer (44) connected to the mains and d secondly, to a series circuit comprising a capacitor (46) and a winding (48b) of a first transformer (48) for transmitting home automation signals in FSK modulation, said secondary winding of the supply transformer (44) and said serial circuit (46,48b) being connected in parallel to the ground to which is also connected one end of the line (50) for transmitting the supply voltage to the multiservice unit and the alarm signals and FSK modulation home automation, a first winding (34a) of a second transformer (34) with ferrite core connected to the midpoints of the first windings (33a, 35a) of second transformers (33,35) with core cores of ferrite of the means for transmitting the call and meter reading signals having its midpoint connected to a parallel circuit formed by the primary winding of a supply transformer (52) on the multiservice unit side and a serial circuit comprising a capacitor (56) and a winding (54b) of a second transformer (54) for transmitting home automation signals with FSK modulation, said parallel circuit being connected to the other end of the line (50) of transmi supply voltage, alarm and home automation signals.