WO2010043612A1

WO2010043612A1 - Avionic system comprising a controller linked to a peripheral by a line mutualized for power and data

Info

Publication number: WO2010043612A1
Application number: PCT/EP2009/063343
Authority: WO
Inventors: François Guillot; Jean-Marie Courteille
Original assignee: Sagem Defense Securite
Priority date: 2008-10-13
Filing date: 2009-10-13
Publication date: 2010-04-22
Also published as: FR2937199A1; FR2937199B1

Abstract

According to a first aspect the invention relates to a device forming a central controller (C) to be linked to a remote peripheral (P) by way of an electrical data and power transmission line (L), comprising a power transmitter (1) and a low-pass filter (MD-L_C, C_{C_BF}) which is arranged between the power transmitter and the electrical line, as well as means for transmitting/receiving data (3) in baseband and a high-pass filter (MD-L_C, C_{C_BF}) arranged between the data transmission/reception means and the electrical line, the electrical line being shared such that power is transmitted at low frequency from the central controller to the remote peripheral and data is simultaneously bidirectionally transmitted in baseband at high frequency between the central controller and the remote peripheral. The invention also relates to a remote peripheral (P) as well as to the system comprising a central controller linked to a remote peripheral by a shared electrical line for the simultaneous transmission of power and of bidirectional data.

Description

AVIONIC SYSTEM COMPRISING A CONTROLLER CONNECTED TO A DEVICE BY A MUTUALIZED LINE FOR POWER

AND THE DATA

The field of the invention is that of avionic equipment.

The invention relates more precisely to avionic systems comprising a central controller and a remote peripheral equipment connected to the central controller via a data exchange electrical line. Avionics systems now include remote data concentrator devices. These include measurement equipment or small remote actuators and distributed at various locations on the aircraft.

The electrical data exchange line is typically a simultaneous bidirectional communication channel between the central controller and a remote device that allows the central controller to transmit its commands and instructions to the remote device and to the remote device. to report back to the central controller.

The data exchanges are typically of the order of 10 ⁶ to 10 ⁷ samples per second, so that a bandwidth of the order of 2 ^* 100 Mbits / s is necessary.

In such avionic systems, an electrical power transmission channel is furthermore necessary for powering the remote device, in addition to the simultaneous bidirectional communication channel ("full duplex").

It is thus desired, on the one hand, to supply electrical power to a remote device (typically 50 to 100 W transmitted) and, on the other hand, to provide a simultaneous bidirectional communication channel with a remote device (typically up to 50m) with a useful information rate of 2 x 100 Mbps (100 Mbps in each direction of communication). Furthermore, an avionics system is intended to be used in a composite aircraft environment that has specific constraints, particularly with regard to the design of embedded electronic components (compliance with the DO254 standard). Thus, to ensure a 1500 V isolation (or more) responding to specific lightning stresses, it is necessary to oppose a high impedance path to the induced current passages. Moreover, the constraints of Electro Magnetic Compatibility (EMC) impose that the EMC reference is not to the metallic mass (structure of the aircraft), at least for the low frequency components of the transmitted signals.

A so-called online line carrier (CPL) technology is known that makes it possible to pool a single two-wire line for transmission of power and bidirectional data. According to this technology, the digital information is modulated and superimposed on the electrical signal so that it can pass through the power lines.

However, the CPL technology is very polluting in terms of radiation and therefore incompatible with the EMC constraints of an airplane environment. The DO254 justification of commercial components

(COTS components: Commercial Off The Shelf) complex is also very difficult to achieve.

PLC technology is therefore unsuitable for use in an avionics system.

Nevertheless, it would be wise to be able to use the information transmission line both to carry data passing in simultaneous bidirectional mode between the controller and the device and to power the device with electrical power, this while respecting the constraints specific to the environment in which this system is intended to be used.

The invention aims to meet this need and proposes for this purpose, according to a first aspect, a central controller device intended to be connected to a remote device via a power line. transmission and power supply system, comprising a power transmitter and a low-pass filter arranged between the power transmitter and the power line, as well as baseband data transmission-reception means and a filter high pass arranged between the data transmission / reception means and the power line, the power line being thus mutualised for the transmission of low frequency power from the central controller to the remote device and for the simultaneous bidirectional transmission of data in high frequency baseband between the central controller and the remote device. According to a second aspect, the invention proposes a remote peripheral device intended to be connected to a central controller via an electric data transmission and power supply line, comprising a power receiver and a pass filter. arranged between the power receiver and the power line, as well as base-band data transmission-reception means and a high-pass filter arranged between the data transmission-reception means and the power line, the electrical line being thereby mutualised for the transmission of low frequency power from the central controller to the remote device and for simultaneous bidirectional transmission of high frequency baseband data between the central controller and the remote device.

Some preferred but non-limiting aspects of the first and second aspects of the invention are the following:

the data transmission / reception means comprise a differential transformer able to discriminate, among the data transiting on the electrical line, the data transmitted locally from the data to be received;

- The differential transformer has two identical windings in series to multiply the voltage on the line by two and add it to the voltage emitted locally, so as to find the voltage corresponding to the received message; the data to be received discriminated by the differential transformer travels through a reception circuit comprising a hysteresis comparator able to reconstruct the binary states of the received message;

the reception circuit further comprises means for regenerating the clock of the received message;

the locally transmitted data travels a transmission path comprising a high-pass filter receiving the data to be transmitted in the form of a binary signal and adapted to ensure a zero average component by transmitting only the high frequency components of the message spectrum; ;

the transmission path further comprises a transmission amplifier having a quasi-zero output resistance;

the emission path further comprises a resistor of equal value to the characteristic impedance of the power line; the transmission-reception means are configured to transmit the baseband data according to the NRZ coding;

the transmission-reception means are configured to implement scrambling and self-correction functions;

According to another aspect, the invention proposes a system comprising a central controller device according to the first aspect of the invention connected via a power line to a remote peripheral device according to the second aspect of the invention. invention.

Other aspects, objects and advantages of the present invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and with reference to the appended drawings in which: : Figure 1 illustrates a possible embodiment of a central controller and a remote device according to the invention; FIG. 2 illustrates a possible embodiment of a central controller according to the invention; FIG. 3 represents timing diagrams corresponding to the various signals reported in FIGS. 1 and 2; FIG. 4 represents a possible embodiment of a high level processing performed on the incoming and outgoing data. Referring to FIG. 1, there is shown a central controller C connected via a data exchange line L, typically a two-wire line, to a peripheral device P. More precisely, a peripheral device P is connected to the line L via a connection interface.

As will be detailed hereinafter, the central controller (C) performs: The supply of the line L, typically in low-level DC voltage (for example 28 or 42 Vdc), for the transmission of power to the remote device P The segregation of the communication signals is ensured by the addition of impedances in series in the transmission line (MD-Lc differential mode inductances for high frequency components), a capacitor C _C _ _BF to ensure a path low impedance to high frequency signals and galvanic isolation of the power transmitter (converter 1) for low frequency components. - High frequency coupling for the transmission of bidirectional binary information. The segregation of the supply voltages is carried out by high pass filtering (capacitor C _C _BF) -

The coupling and the differentiation of the incoming and outgoing data are ensured in transmission-reception means 3 by a high frequency differential transformer 5, a resistance Zc 8, an emission amplifier EM 7 and reception means 9, 10 .

- For the transmission part, the DC component is suppressed by a high pass filter 6. - In reception, the message is made exploitable by means 10 for creating a "bit" clock and sampling the data by this clock at the moment of best possible discrimination between logic level 1 and logic level 0. - In short, incoming and outgoing signals from the central controller

C (the same is true for the remote device P) are the power supply via the power transmitter 1 (the power reception via a power receiver 2 for the remote device), the incoming data Data-ln, the outgoing Data-Out data, and the SL line signal.

The central controller C comprises a power transmitter (converter 1), preferably isolated to comply with aircraft manufacturer recommendations regarding the resistance to the effects of lightning and EMC constraints. Two MD-Lc inductors can be used to limit the high-frequency coupling in differential mode between the equipment connected by line L.

The role of the differential mode inductors is to increase the common mode serial impedance of the transmission line with respect to the disturbances transmitted (by the converter 1) or received by the line itself. They can be of high value, and thus of such a high impedance, which is a favorable contribution to the holding of the EMC (susceptibility and emission) constraints.

Differential mode inductors have the role of increasing the impedance of the differential mode line with respect to the high frequency components coming from the converter 1. The final objective, in addition to the overall improvement vis-à-vis the EMC compatibility, is to limit as much as possible the level of noise transmitted on the line, the latter degrading the signal-to-noise ratio of the received message and therefore being detrimental to the good reception capacity of the bits transmitted by the line. The central controller C comprises a low-pass filter arranged between the power transmitter 1 and the power line L.

The central controller C also comprises baseband data transmission / reception means 3 and a high-pass filter arranged between the data transmission / reception means 3 and the line L.

According to one possible embodiment of the invention, the high-pass and low-pass filters are conventional L and C filters. As shown in FIG. 1, the high-pass filter is thus formed by the inductance MD-Lc and the capacitor C _C _ _BF (at low frequency, the inductance MD-Lc behaves like a closed switch and the capacitor C _C _ _BF as an open switch), while the low-pass filter is formed by the same elements (MD-Lc and C _C _ _BF ) with inverse behaviors. This allows to have a negligible influence vis-à-vis the data transfer (broadband) and power (low frequency and / or direct current) without mutual pollution of different information.

As shown in Figure 1, the device P comprises a power receiver 2, preferably isolated to meet the aircraft manufacturers recommendations regarding resistance to the effects of lightning. The structure of the device is for the rest similar to that of the central controller.

The peripheral P thus comprises a low-pass filter arranged between the power receiver 2 and the line L. The peripheral P also comprises data transmission-reception means in baseband 4 as well as a high-pass filter. arranged between the data transmission-reception means and the electric line L.

These filters are formed by the inductance MD-Lp and by the capacitor Cp BF, which provide a filtering function similar to that implemented by the inductance MD-Lc and the capacitor C _C _ _BF of the central controller C. Thus in the context of the invention, the supply voltage is isolated from the data by means of passive high-pass and low-pass filters. Line L is thus pooled for transmitting power from the controller to the remote device and for simultaneous bidirectional transmission of baseband data between the controller and the device. The baseband data transmission / reception means 3 of the central controller C and the baseband data transmission / reception means 4 of the remote device P are each configured to transmit data "Data-ln" and to receive data-out data

The transmission-reception means 3, 4 make it possible to add two bitstreams to the supply voltage on a single electrical data exchange line (a rising stream corresponding to the data transmitted by the remote device P to destination of the central controller C, a downstream flow corresponding to the data transmitted by the controller to the remote device P). FIG. 2 shows a possible embodiment of a central controller C according to the invention, in particular transmission-reception means 3 of the controller C. It will be understood, however, that this description also applies to transmission-reception means 4 of the remote device P. As such, the similar elements bear the same references in FIGS. 1 and 2.

Data release (Figure 3)

Preferably, the transmission-reception means 3, 4 are configured to transmit the baseband data according to the NRZ coding. As shown in FIGS. 1 to 3, the transmission-reception means 3 of the controller C are configured to transmit a binary message "NRZ-E" while the transmission-reception means 4 of the peripheral P are configured to transmit a binary message "NRZ-Ed".

The data to be transmitted ("NRZ-E" in the case of the central controller C) travels through a transmission circuit. Preferably, the transmission circuit comprises a high-pass filter 6 which receives the data to be transmitted "NRZ-E" in the form of a binary signal in the NRZ format, and which ensures a zero average component to these data in transmitting only the rising and falling edges of the NRZ binary message. The resulting signal is represented under the label "EM" in FIG.

Similarly, the transmission-reception means 4 of the peripheral P comprise a high-pass filter 6 for transmitting only the rising and falling edges of the binary message "NRZ-Ed" in the form of an "EMd" message represented by in Figure 3.

Returning to the description of the transmitting-receiving means 3 of the central controller C, the resulting signal "EM" is transmitted on the electrical line L through a resistor 8 of value Zc equal to the characteristic impedance of the power line. L, then through a differential transformer 5 which ensures, as will be described hereinafter the function of differentiation of incoming and outgoing flows, and which also plays an isolation function.

The transmission circuit may further comprise, downstream of the high-pass filter 6, an emission amplifier 7 having a very low output resistance (considered to be almost zero). In this way, the output voltage only includes the message sent locally.

Receipt of data

The data SL transiting on the electrical line correspond to the EM signal emitted by the central controller and to the EMd signal emitted by the device P. Thus, a simultaneous bidirectional transmission on the electric line L.

FIG. 3 represents such a signal SL corresponding to the addition of the two flows EM (downward flow) and EMd (upstream flux) on the line L.

The transmission-reception means 3 of the controller C comprise a differential transformer 5 able to discriminate, among the data SL transiting on the electrical line L, the data transmitted locally (NRZ-E) data to receive (NRZ-Ed).

The differential transformer thus makes it possible to segregate the downward flow of the upstream flow. According to a preferred embodiment, the data are present on the line in a ratio V 1 with respect to the emitted voltage V _EM (see FIG. 2) and the differential transformer 5 comprises two identical windings in series so as to multiply these voltages by two and to subtract them from the voltage emitted locally directly at the output of the emission amplifier 7. The resultant is then 2 * (V _E M / 2 + V _E MCI / 2) - V _E M = V _EM d , where V _EM represents the voltage emitted locally by the central controller and V _EMc ι represents the voltage emitted remotely by the remote device. In this way, we find the voltage V _EM corresponding to the received message REC (see Figure 3).

The rising flux thus discriminated by the differential transformer travels through a reception circuit comprising a hysteresis comparator 9 adapted to reconstitute the message sent by the device. The hysteresis comparator 9 may in particular be made by two simple comparators followed by a RS flip-flop ensuring the storage of transient states (it is effectively recalled that the binary states are not transmitted, but only their transitions). At the output of the RS flip-flop there is the signal REC-F corresponding to the signal "NRZ-Ed" transmitted by the remote device.

It will be noted that the hysteresis comparator 9 is also useful for clearing the received message of any "traces" of the transmitted signal which are not perfectly discriminated by the differential transformer 5.

Recovery of the received binary message (FIG. 4) The reception circuit further comprises means 10 for regenerating the clock which served to constitute the NRZ message.

According to a possible embodiment of the invention, these means for regenerating the clock form a phase-locked loop. The loop realizes more precisely a simple servocontrol latching in phase (a stable position over 360 °) at the moment of the transitions when they take place, that is to say at predetermined temporal positions, but which may be absent during sequences. 0 or 1 in the transmitted message.

The signal REC-F (FIG. 3) at the output of the hysteresis comparator 9 is then sampled by the rhythm recovered by the regeneration means of the clock 10, so as to be correctly restored on the "Data-Out" output. A possible embodiment of the exchanges of the bits between the central controller and the device to which it is connected is as follows. - The transmitting means 3 of the central controller are configured to continuously transmit data to the remote device; - The transmitting means of the P device are configured for transmitting data to the central controller C with a predetermined delay (perfectly deterministic) with respect to the corresponding interval of the master frame.

A possible embodiment of a high level processing carried out at the level of the central controller on the one hand on the incoming data to form the low level data series "Data-ln" provided in FIG. input of the transmission-reception means 3, and secondly the low-level data-output data obtained at the output of the transmission-reception means 3 to constitute the outgoing data. It will be noted that the device performs a similar high level processing.

The development of the interface function of FIG. 4 for the low level layers processed by the transceiver means allows the system to support different avionic protocols (Arinc 429, MIL 1553, TTP, etc.). The electrical layer associated with the Applicant's proprietary digital interface can be customized to interface different avionics standards such as Arinc 429 or others. The solution proposed by the present invention provides a perfectly deterministic digital information exchange support enabling the creation of virtual communication channels. For example, the master coupler can provide an input and output interface for Arinc 429, and likewise for the remote coupler concerned. Two classic Arinc 429 devices can be connected and used in a completely transparent way for them. It could be the same for other communication standards.

This interface function also has the advantage of being able to be implemented using standard programmable components (FPGA).

As shown in FIG. 4, the incoming data is subjected to the following operations in succession. The incoming data is first processed by a block 20 capable of cutting them into 16-bit words and adding synchronization elements (16-bit word delimitering signal transmitted by block 20 to block 21). At block 21, 5 additional bits corresponding to bits for error correction are generated, for example by implementing a Hamming coding. In block 22, a series of 21-bit words from block 21 are stored and thus a series of several words (the number of which is dependent on the parasitic elements present on the transmission line) is constituted. Finally, they are re-issued according to a pseudo-random sequence (scrambling sequence) making it possible to spread the error sequences (false bit sequences) at the time of reception, thus increasing the efficiency of the self-corrector.

Block 30 is the generator of the frames transmitted on the Data-ln line. It generates a sequence of time spaces delimited by synchronization patterns.

The time spaces are supplemented regularly by the data developed in block 22. This is the function of block 23.

The block 24, meanwhile, provides temporary storage (in FIFO mode) of the data transmitted by the block 22, in order to adapt the asynchronisms of the two automata (data and frame from the block 30). The Rhythm differences between the data rate from the block 22 and the provision of time slots are managed by assigning them to filling patterns in the absence of available data.

The block 30 also transmits the synchronization patterns to the block 40, allowing it to synchronize on the incoming data (Data-Out).

The block 23 outputs the Master frames in the form of serial data in baseband, in particular in the NRZ format.

According to a possible embodiment of the invention, these baseband serial data are then filtered by a low-pass filter (not shown) making it possible to reduce the harmonics of the NRZ, before being sent to the transmitting-receiving means. . The low-pass filter is, for example the 6 ^th order, Bessel response to only affect a constant delay, whose cutoff frequency is keyed to 0.7 ^* Frequency Bits. The "Data-Out" data obtained at the output of the transmitting-receiving means, as well as their regenerated clock, are for their part subjected to a block 40 forming a reception interface of the Coupler frames, connected to the block 30 for generating the Master frame. , to extract the serial data and the synchronization bit. In block 41, synchronization and descrambling of the data is performed to reconstruct the 21-bit words. These are processed in block 42 by applying self-correctors to reconstruct the 16-bit error-corrected words. Block 43 forms a user interface for rendering high level data.

It is specified that the invention is not limited to a central controller or a remote device as described above, but also extends to a system, in particular an avionic system, comprising a controller connected to a remote device by the intermediate of a shared power line for transmission of power and bidirectional data. The advantages of this system are in particular the following: a single shared two-wire line for transmission of power and bidirectional data (the line is designed to support a bidirectional bit rate of 100 Mbits / s in each direction and incidentally serve as a support for the transmission of electrical energy. optionally, be a shielded two-wire line or an asymmetrical (coaxial) link, in all cases it is suitable links, ie having a known and characterized iterative impedance, typically 50 or 75W)

- Common lightning protections (fusion of lightning protections for power and signal)

- Different possible communication standards (trivialized deterministic channel that can support different avionics standards by adding a digital overlay interface)

- Simultaneous two-way digital transmission (each stream is independent)

- Minimization of spectral occupancy (as opposed to multicarrier transmission, baseband transmission - NRZ - with limited spectrum by filtering)

- Galvanic isolation of the data line (by coupling transformers)

- Possibility of galvanic isolation of the power line (by the DC / DC or AC / DC converter placed in the Master and Peripheral couplers)

- EMC and Lightning Compatibility (EMC by minimizing the spectrum occupied by transmitted data: NRZ + Filtering, no carrier

High Frequency or Multi Carriers, type COFDM for example. Lightning by the different galvanic insulation proposed).

- Justification DO254 possible, even for the most critical levels by mastering all the complex functions, so possible justification, as opposed to COTS components, whose justifications are not available and virtually unachievable.

Claims

A central controller device (C) for connection to a remote device (P) via a data transmission and power supply line (L), comprising a power transmitter (1) and a low-pass filter (MD-Lc, C _BF _C) arranged between the transmitter power and the power line, and the transmission-reception means (3) of data in the baseband and a high-pass filter (L ₀ , C _{C HF} ) arranged between the data transmission / reception means and the power line, the power line being in this way mutualised for the transmission of low frequency power from the central controller to the remote device and for the simultaneous bidirectional transmission of high frequency baseband data between the central controller and the remote device.

A remote device device (P) for connection to a central controller (C) via an electrical data transmission and power supply line (L), comprising a power receiver (2) and a low-pass filter (MD-Lp, C _{P BF} ) arranged between the power receiver and the power line, as well as baseband data transmission / reception means (4) and a high-pass filter ( MD-Lp, C _{P HF} ) arranged between the data transmission / reception means and the power line, the power line being in this way mutualised for the transmission of low frequency power from the central controller to the remote device and for the simultaneous bidirectional transmission of high frequency baseband data between the central controller and the remote device.

3. Device according to one of claims 1 or 2, wherein the data transmission / reception means (3, 4) comprise a transformer differential (5) able to discriminate, among the data transiting on the power line, the data transmitted locally (EM) data to receive (REC).

4. Device according to claim 3, wherein the differential transformer (5) comprises two identical windings in series to multiply the voltage on the line by two and add it to the voltage emitted locally, so as to find the voltage corresponding to the message received.

5. Device according to one of the two preceding claims, wherein the data to be received discriminated by the differential transformer flows through a reception circuit comprising a hysteresis comparator (9) adapted to reconstruct the binary states of the received message (REC-F). .

6. Device according to the preceding claim, wherein the receiving circuit further comprises means for regenerating the clock (10) of the received message.

7. Device according to claim 3, wherein the locally transmitted data travels a transmission path comprising a high-pass filter (6) receiving the data to be transmitted in the form of a binary signal and adapted to ensure a zero average component. transmitting only the high frequency components of the message spectrum.

8. Device according to claim 3, wherein the transmission path further comprises a transmission amplifier (7) having a virtually zero output resistance.

9. Device according to claim 3, wherein the transmission path further comprises a resistor (Zc) of equal value to the characteristic impedance of the power line.

10. Device according to one of the preceding claims, wherein the transmitting-receiving means are configured to transmit the baseband data according to the NRZ coding.

11. Device according to one of the preceding claims, wherein the transmitting-receiving means are configured to implement scrambling and self-correction functions.

A system comprising a central controller device (C) according to claim 1 connected via a power line (L) to a remote device device (P) according to claim 2.