FR2830941A1 - Surveillance system for telecommunication cable includes module integrated into cable, deriving power from cable and transmitting monitoring data - Google Patents

Abstract

The cable includes surveillance devices (4) distributed along its length. Each surveillance device includes a sensor (7) for collecting data (D) from the cable, and a circuit (8) for transmitting this data by radio. A supply circuit (9) derives power from an inductive coupling with the cable. The signal transport cable includes several surveillance devices (4) distributed along the length of the cable (1). Each surveillance device is miniaturized on a substrate and integrated into the cable. It includes a sensor (7) for collecting at least one item of data (D) which is intrinsic to the cable, and a circuit (8) for transmitting this data, combined with identifying data (ID) relating to the specific device, by radio. A supply circuit (9) provides a direct voltage (Vd) for both the sensing component and the transmitting component. This may derive power from an inductive coupling with at least one conductor element included within the cable and carrying an alternating current.

Description

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Cable and its monitoring system
The present invention relates to the monitoring of extrinsic or intrinsic data to an electrical cable, or telecommunications, including fiber optics.

 It is particularly intended to record the characteristic data at one or more predetermined locations on the cable.

 To this end, a cable is characterized in that it comprises several passive monitoring devices distributed along the cable each comprising means for sensing at least one piece of data relating to the cable, means for transmitting the captured data radioelectrically and means for supply for supplying DC voltage to the means for sensing and the means for transmitting.

 According to certain embodiments of the invention described in more detail below, the power supply means in the monitoring devices can be coupled by electromagnetic induction to at least one conductive element included in the cable and capable of being traversed by a current alternatively, or receive an unmodulated power radio carrier transmitted from outside the cable. In another embodiment, the monitoring devices are fixed on a ribbon of insulating material reported longitudinally on the cable and comprising two longitudinal electrical conductors connected to the supply means in the monitoring devices and having ends that can be connected to a cable. DC voltage source.

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 The invention also relates to a system for monitoring a cable. The system comprises several monitoring devices included in the cable according to the invention, and means for reading outside the cable to receive the data transmitted by the monitoring devices. The reading means can be portable.

 The reading means may comprise a radiating cable running along the cable and a receiver connected to one end of the radiating cable to receive the data transmitted by the means for transmitting in the monitoring devices.

 For a cable whose monitoring devices receive power from an unmodulated carrier, the reading means can itself transmit the unmodulated carrier to the monitoring devices. In this case, the reading means may comprise a radiating cable running along the cable to be monitored, a means for generating the unmodulated power carrier through the cable radiating towards the power supply means in the monitoring devices, and a receiver for receiving through the cable radiating the data transmitted by the means for transmitting in the monitoring devices.

 Other features and advantages of the present invention will emerge more clearly on reading the following description of several preferred embodiments of the invention with reference to the corresponding appended drawings in which: FIG. 1 is a schematic longitudinal view of a cable three-conductor incorporating monitoring devices into a

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 monitoring system according to a first embodiment of the invention; Figure 1A is a cross section taken along the line A-A of the cable of Figure 1; FIG. 2 details a monitoring device according to the first embodiment of the invention electromagnetically coupled to a conductive element of the cable and transmitting an identifier and data to a radio receiver; FIG. 3 schematically shows a monitoring system according to a second embodiment of the invention, in which the monitoring devices are remote-fed by a radio carrier transmitted by the reader; - Figure 4 shows schematically a monitoring system according to a third embodiment of the invention, wherein the monitoring devices are fed through the electrical conductors reported on the cable to monitor; FIG. 5 diagrammatically shows a monitoring system according to a fourth embodiment of the invention, in which the monitoring devices are electromagnetically independantly fed as in the first embodiment, but transmit identifiers and data to a reader through a radiating cable; and FIG. 6 schematically shows a monitoring system according to a fifth embodiment of the invention, in which the monitoring devices are tele-fed through a radiating cable which receives identifiers and data transmitted by the monitoring devices.

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 According to a first embodiment of the invention shown in FIGS. 1 and 2, a monitoring system monitors an electrical or telecommunications power cable 1 comprising a plurality of insulated metallic wire conductors 2 contained in an outer sheath or envelope 3. The monitoring system comprises several passive monitoring devices 4 distributed longitudinally in the cable and incorporated in or fixed on or under the sheath 3 during the manufacture of the cable. According to the embodiment illustrated in FIGS. 1 and 1A, the devices 4 are flush with the external face of the sheath 3. The monitoring system also comprises a mobile and portable radio-receiver-receiver, external to the cable and powered by a battery or by the electrical sector. .

 Each monitoring device 4 shown in detail in FIG. 2 is organized around a microcontroller 6 including a non-volatile memory having previously stored in particular a respective identifier ID of the monitoring device. In the device 4 are connected to the microcontroller 6 at least one sensor 7 for collecting a data D relative to the cable 1, a radiofrequency transmitter 8 for periodically transmitting the identifier ID and the data D to the reader radio receiver 5 outside the cable, and a supply circuit 9 for supplying the aforementioned elements 6, 7 and 8. All the elements 6 to 9 are miniaturized and integrated on a dielectric substrate of a few square millimeters. In particular, the radio transmitter 8 and the supply circuit 9 respectively comprise an antenna 81 of the antenna plate or pad type (in English terminology "patch")

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 and a coupling inductor 91 printed in the substrate.

 The data D picked up by the sensor 7 and applied in the form of a binary word to the microcontroller 6 may be a physical characteristic on the environment of the cable such as the temperature or the pressure or the hygrometric state prevailing around the cable, or a constraint intrinsic to the cable such as an elongation, or an electrical quantity such as current, voltage, capacitance. As a variant, several of these extrinsic or intrinsic data to the cable are picked up by several sensors included in the device 4 and transmitted by the transmitter 8.

 The identifier ID issued in conjunction with the data D serves to distinguish the monitoring device 4 from other monitoring devices and implicitly to locate the monitoring device along the cable.

 The identifier ID and the data D are transmitted periodically, for example by amplitude, frequency or phase modulation in the microcontroller 6 and by frequency transposition in the transmitter 8 which emits a modulated carrier of frequency F. transmission is cyclic so that the data and identifiers issued by the monitoring devices adjacent to a given monitoring device do not overlap and thus be time multiplexed.

 The transmission frequency F of the transmitter 8 is different from the signal frequencies normally transmitted by the conductors 2 of the cable 1. If the cable transmits an electrical signal, the baseband frequency of the modulated signal in the microcontroller 6 is different. the frequency of the alternating voltage of 50 or 60 Hz, and if the cable

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 transmits a telecommunications signal, the transmission frequency F does not belong to the range of useful frequencies of the telecommunications signals transmitted by the cable. For example, the transmission frequency F is equal to 433 MHz.

 According to the first embodiment shown in Figures 1 and 2, the power supply circuit 9 is inductively coupled with a power supply element included in the cable and may be traversed by an electric current IA after the cable is installed. The conductive element consists of one or more of the wired conductors 2 in the cable, or else consists of any other metal element extending longitudinally, including helically, in the cable, such as an integrated screen or shield 31 to the sheath 3 of the cable, or such as a wire or wire strand 32 in the center of the cable or one or more wire frames 33 embedded in the sheath 3 and / or housed under the sheath 3 inside the cable.

 In order not to disturb the signals transmitted by the cable, the frequency FA of the remotely powered current injected into the supply conductor element included in the cable does not belong to the range of useful frequencies of the signals transmitted in the cable. However, the FA frequency should not be too high so that the remote power supply does not weaken too much. Typically for a range of a few hundred meters, the AC supply current is a few milliamperes and FA frequency below about 1 MHz. For an electric power cable, the supply frequency FA may be between

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 1 kHz and 1 MHz. For a low-speed telecommunications cable, the FA frequency may be between 100 kHz and 1 MHz.

 The remote power supply current IA is produced by a current generator 10 connected to one end of the supply conductive element 2, 31, 32, 33. The supply circuit 9 of the monitoring device 4 is electromagnetically coupled to the supply conductive element by means of the inductor 91 which, with a capacitor 92, constitutes an oscillating circuit tuned to the frequency FA of the remote power supply IA. The AC induced AC voltage at the terminal of the oscillating circuit is applied to means 93 for generating a DC voltage Vd supplying the microcircuits 6, 7 and 8 included in the device 4. The means 93 may comprise a rectifier, a filter and a limiter of voltage for supplying the DC voltage Vd and a demodulator for supplying a clock signal H to a time base included in the microcontroller 6.

 According to a variant of the first embodiment as well as according to other embodiments described below, the cable to be monitored is a cable containing optical fibers in place of the wire conductors 2 or in combination therewith and comprises at least one conductive element of the remote feed current IA at the frequency FA in order to inductively induce the induced voltage VA which is converted into a direct supply voltage Vd, The conductive element may also be a metal reinforcement such as a strand or a metal wire. center of the cable and / or one or more frames to the

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 periphery of the cable or under the outer sheath of the cable.

 According to a second embodiment shown in FIG. 3, the monitoring system monitors a cable 1a of the same type as the cable 1 according to the first embodiment, but without requiring a supply current conducting element. For example, the cable to be monitored may be a fiber optic cable without metal element.

 In this second embodiment, the portable reader 5a transmits an unmodulated carrier PA, acting as a power supply signal, which is picked up by a reception antenna in the form of a microwave antenna of the type integrated in each monitoring device 4a on or incorporated in the cable la in order to apply it to a supply circuit 93a supplying a supply voltage Vd and a clock signal H. The aforesaid receiving antenna with a matching circuit impedance can be confused with the transmitting antenna 8la.

 Alternatively, the receiving microwave antenna may be replaced by a resonant circuit 91a-92a tuned to the frequency of the power carrier PA emitted by the reader 5a.

 Thus, each monitoring device 4a is still purely passive but is powered by a source of energy external to the cable of the invention to be monitored. Moreover, the device 4a contains microcircuits 6a, 7a and 8a similar to those 6, 7 and 8 described in the first embodiment, so that these circuits emit the identifier ID and at least one data D modulating the frequency carrier F towards the reader 5a. In practice, the

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 portable reader 5a is responsive to the reception of the identifier ID and data D in response to the unmodulated PA power carrier acting as a read request signal that it transmits, for a distance of the order of one meter relative to each monitoring device 4a.

 In a third embodiment shown in Figure 4, the monitoring system monitors a cable lb which does not necessarily include an electrical conductive element.

 In this third embodiment, the monitoring devices 4b have their substrates fixed beforehand, for example by gluing, on one side of a thin ribbon 41 of flexible and insulating material. The ribbon 41 supports two printed or glued longitudinal metal conductors 42, for example copper or aluminum. Ends of the conductors 42 are connected to the terminals of a DC voltage source 10b such as batteries. Power supply terminals of the elements 6b, 7b and 8b in each monitoring device 4b are connected to the power supply conductors 42 extending on or under the substrate of the device 4b, directly or via a continuous converter. Continuous included in the supply circuit 9b. The devices 4b are thus supplied in parallel by the DC voltage source 10b.

 The identifier ID and the data D are sent to the reader-receiver 5b in the same way as in the previous embodiments.

 According to a fourth embodiment shown in FIG. 5, the electrical or telecommunication cable lc of the invention to be monitored is

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 of the same type as the cable 1 according to the first embodiment (Figure 2) or lb according to the third embodiment (Figure 4). For example, the cable lc includes a conductive element capable of being traversed by an alternating current of remote power supply IA at the frequency FA and electromagnetically coupled to the inductance 91c included in the supply circuit 9c of each monitoring device 4c. .

 In the fourth embodiment, the monitoring system comprises, as reading means, a radiating cable 51c and a reader-receiver 5c. The radiating cable 51c is for example of the coaxial type with periodic patterns of slots or holes and extends along the cable to be monitored 1c and against it or at a distance thereof of up to about 1 meter. The reader 5c is coupled to one end of the radiating cable 51c to receive the ID and D data modulating the frequency carrier F and issued cyclically by the devices 4c, each in turn. In practice, the radiating cable 51c is installed in the same underground pipe containing the cable lc or is fixed against the cable lc before the laying thereof.

 A fifth embodiment according to the invention combines the unpowered power supply feeder PA according to the second embodiment (FIG. 3) and the receipt of identifier and data by radiating cable 51d according to the fourth embodiment (FIG. 5). as shown in FIG. 6. The cable of the invention to be monitored ld may not include a conductive element since no remote power supply

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 crossing the cable ld is necessary. Each monitoring device 4d on or incorporated in the cable to be monitored ld is analogous to the monitoring device 4a according to the second embodiment shown in FIG.

 The reading means according to the fifth embodiment consists of a radiating cable 51d along the cable to be monitored ld and a reader 5d.

The reader 5d is equipped not only with a receiver but also with an unmodulated power carrier transmitter PA emitted through the radiating cable 51d and diffused by it to the monitoring devices 4d. The antennas or the tuned circuits 91d-92d in the power supply circuits 9d pick up the carrier PA and convert it into a DC voltage Vd applied to the microcircuits 6d, 7d and 8d included in the devices 4d. As in the fourth embodiment, the radio transmitter 8d in each monitoring device 4d cyclically emits, in a predetermined time window, the identifier ID and the respective data D modulating the carrier at the frequency F which is picked up by the radiating cable 51d so that the 5d reader retrieves the identifiers and the data.

Claims (15)

1-Cable characterized in that it comprises several passive monitoring devices (4) distributed along the cable (1) each comprising means (7) for sensing at least one piece of data (D) relative to the cable, means (8) ) for transmitting the captured data radioelectrically and a supply means (9) for supplying DC voltage (Vd) the means for sensing and the means for transmitting.  2-cable according to claim 1, wherein each monitoring device is miniaturized on a substrate of a few square millimeters.  3-cable according to claim 1 or 2, characterized in that the monitoring devices (4) are fixed on or under or incorporated in a sheath (3) of the cable (1).  4-cable according to any one of claims 1 to 3, wherein the means for transmitting (8) transmits a respective identifier (ID) of the monitoring device (4) together with the transmitted data (D).  A cable according to any one of claims 1 to 4, wherein the transmitted data is a physical feature on the environment of the cable, or intrinsic strain on the cable.  6-cable according to any one of claims 1 to 5, characterized in that the supply means (9; 9c) in the devices <Desc / Clms Page number 13>  monitoring devices (4; 4c) are electromagnetically coupled to at least one conductive element (2, 31, 32, 33) included in the cable (1; 1c) and capable of being traversed by an alternating current (IA).  7-Cable according to claim 6, wherein the current (IA) capable of passing through the conductive element (2, 31, 32, 33) has a frequency (FA) that does not belong to the useful frequency range of an electrical or telecommunications signal transmitted in the cable.  8-cable according to claim 6 or 7, wherein the current (IA) likely to pass through the conductive element (2,31, 32,33) is a few tens of milliamperes and has a frequency below about 1 MHz.  9-System according to any one of claims 1 to 5, characterized in that the supply means (9a, 9d) in the monitoring devices (4a, 4d) receive an unmodulated power carrier (PA) emitted from outside the cable.  10-cable according to any one of claims 1 to 5, characterized in that the monitoring devices (4b) are fixed on a tape (41) of insulating material reported longitudinally on the cable (Ib) and having two electrical conductors longitudinal members (42) connected to the supply means (9b) in the monitoring devices (4b) and having <Desc / Clms Page number 14>  ends likely to be connected to a DC voltage source (lOb).  11-System for monitoring a cable, characterized in that it comprises several monitoring devices (4) included in the cable (1) according to any one of claims 1 to 10, and an outer reading means (5) cable to receive the data transmitted by the monitoring devices.  12-System according to claim 11, wherein the reading means (5) is portable.  A system according to claim 11 or 12 for the cable according to claim 9, wherein the reading means (5a; 51d, 5d) outputs the unmodulated power carrier to the monitoring devices.  14-System according to claim 11, characterized in that the reading means comprises a radiating cable (51c) along the cable to monitor (lc) and a receiver (5c) connected to one end of the cable radiating to receive the data (D) transmitted by the means for transmitting (8c) in the monitoring devices (4c).  15-System according to claim 11 for the cable according to claim 9, characterized in that the reading means comprises a radiating cable (51d) along the cable to be monitored (ld), means (5d) for generating a carrier unmodulated power (AP) through the cable radiating to the supply means (9d) in the devices <Desc / Clms Page number 15>  monitoring device (4d), and a receiver (5d) for receiving through the cable radiating data (D) transmitted by the means for transmitting (8d) in the monitoring devices (4d).