Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L3/00—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal
  • B61L3/02—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control
  • B61L3/08—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically
  • B61L3/12—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically using magnetic or electrostatic induction; using radio waves
  • B61L3/125—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal at selected places along the route, e.g. intermittent control simultaneous mechanical and electrical control controlling electrically using magnetic or electrostatic induction; using radio waves using short-range radio transmission
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L3/00—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal
  • B61L3/16—Continuous control along the route
  • B61L3/22—Continuous control along the route using magnetic or electrostatic induction; using electromagnetic radiation
  • B61L3/225—Continuous control along the route using magnetic or electrostatic induction; using electromagnetic radiation using separate conductors along the route
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B61—RAILWAYS
  • B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
  • B61L3/00—Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal
  • B61L3/16—Continuous control along the route
  • B61L3/22—Continuous control along the route using magnetic or electrostatic induction; using electromagnetic radiation
  • B61L3/227—Continuous control along the route using magnetic or electrostatic induction; using electromagnetic radiation using electromagnetic radiation

Definitions

• the present invention relates to the field of information transmission between the ground and mobiles. It relates, more particularly, but not limited to, the transmission of information between the ground and railway mobiles, traction units, cars or wagons, trainsets or trains.
• Some of these means have a point coverage, that is to say limited to a few tens of centimeters, or even a few meters and can therefore only be used when the mobile passes in well-defined locations.
• some are unidirectional, such as traditional light signaling or its repetition in the cabin by metal contact or inductive loop. More recent techniques, such as microwave or optics (infrared), allow the establishment of bidirectional links between a mobile and a "beacon" offering a high speed.
• Radio means of communication have more coverage. They are essentially radio means.
• the transceiver with which the mobile has exchanges (which in some cases are only one-way) is located either in space (telecommunications satellites) or on the ground. In the latter case, it is exceptionally a station with a large coverage and most often, because of the frequency band used, a set of fixed stations with a range limited to a few kilometers and therefore organized network.
• the information rate of these radio links is generally limited by the relative narrowness of the available frequency band. Even more than the overall speed, the speed by mobile is limited by the number of mobiles in the coverage area between which to share the available speed.
• a third type of means of communication has coverage which is neither punctual nor extended to a relatively large area in its two dimensions. These are means whose coverage is somewhat linear, so as to cover a section of railway or road.
• the means used can be a radiating cable, a lossy waveguide, or even, in the case of the railway, the rails, but the transmission is then unidirectional.
• the speed generally available for transmission with a mobile is proportional not only to the speed of the link when it is established but also to the proportion of the time when it is established, that is to say at relationship between the length of the area covered by a point connection and the spacing between successive covered areas.
• the average speed is sufficient, its discontinuous nature over time makes it necessary for a service like the telephone, asking a priori continuity, temporary storage, therefore a high apparent response time.
• a third drawback affects certain particularly fast mobiles using radio transmission with a high modulation rate and certain modulation methods; this is the Doppler effect which can prohibit digital links with too fast mobiles.
• linear coverage transmissions are, as regards rail transmissions, their unidirectional nature and their very low bit rate, as regards radiating cables their cost and their still limited frequency range (it is difficult today hui to go up very much beyond 1 GHz) being able to prohibit to transpose on this particular antenna which is the cable a transmission in the open air (repetition in tunnel of connections with satellites, for example), and as regards slotted waveguides, their cost.
• the present invention aims to allow transmission between the ground and mobiles with a high information rate with each mobile, coverage in some cases continuous and for a moderate cost.
• the object of the invention is a ground-mobile transmission system, using microwave transmission beacons of the type of those which are usually used to ensure punctual transmissions, characterized in that the coverage is extended in the direction of movement of the vehicle, by equipping it with an antenna or other radiating device whose coverage in the direction of movement is much greater than its value in the transverse direction during movement and may even, if it reaches or exceeds the distance separating successive beacons, allow a continuous connection during the movement of the vehicle.
• Another object of the invention is a transmission system between the various beacons located on the path of a vehicle which is particularly suitable for the ground-mobile transmission system envisaged and ensures under the best conditions the sharing of available transmission resources and the routing of information between a Nodal Transmission Center and the punctual beacons successively covered by the antenna of a vehicle.
• the invention relates to a system in which the roles which, in the state of the art of linear coverage transmissions, are respectively assigned to the ground and to the mobiles are reversed.
• It is the ground which carries, at more or less regular intervals, fairly simple beacons (linked together by a transmission network which constitutes the second object of the invention) and it is the mobile which carries a complex transceiver, connected to a large antenna, such as a radiating cable or a slot waveguide placed for example over the entire length of a train, and which, through this antenna, is in permanent contact with at least one point marker of a set, if the distance between tags is less than or equal to the length of the antenna, or which, if this distance is greater than the length of the antenna, ensures a link which, without being continuous, exists on a proportion of the path traveled sufficient to allow a high average flow between the mobile and the ground. Because a beacon is only in contact with at most one mobile at a time, the speed guaranteed to a mobile is not at the expense of that assured to
• FIG. 1 schematically represents a section of railway line equipped with beacons and a transmission network connecting them to a nodal transmission center, traversed by a train fitted with a reader connected to a distributed antenna according to the invention
• FIG. 2 shows the detail of a slotted waveguide fitted to a train and serving as a distributed antenna according to the invention
• FIG. 3 shows the detail of a method of fixing the slotted waveguide under the body of the powerplant and / or elements of the train;
• FIG. 5 gives an arrangement of the waveguide antenna in two sets each covering one half of the train and making it possible to harmoniously ensure the transition between one beacon and the next, in the case of continuous transmission;
• FIG. 6 describes the architecture of a network connecting together the nodes to which the beacons are connected and to a nodal transmission center; possibly other distributed equipment, such as needle controllers;
• FIG. 7 shows the structure of a node.
• the mobile which in the case taken for example is a train, is equipped with a "reader" as proposed, essentially for hands-free toll applications or container identification, by the companies CGA-HBS
• the beacon To transmit in the train-to-ground direction, it modulates a carrier, generally in amplitude. To read the content of the message awaiting reading in the beacon equipping the rail line and intended for the train, it illuminates the beacon with an unmodulated microwave wave. The beacon reflects part of it, by modulating the reflected wave in amplitude (shorting of the antenna modulated by the content of a memory such as a shift register), in frequency or sometimes in phase, or by any other process.
• the speeds of such readers are typically of the order of 500 kbit / s and can reach IMbit / s but the bi-directional speed is only half as long as the response of the beacon, which requires unmodulated illumination , cannot be done at the same time as sending a message to the tag.
• Certain systems have a more limited bit rate but essentially in order to decrease the energy consumed by the beacon, which is a consideration of less importance with the transmission system of the invention, in which a remote supply of the beacons through the system terrestrial transmission will be as often as possible.
• the various beacons are connected to nodes, such as Ni, Nj, Nk, themselves spaced 200m apart. These nodes are, in their turn, in connection with a Central Nodal of Transmissions, such as CNT on the one hand, and can on the other hand be connected to a fixed railway installation such as IF, controlling for example a needle motor .
• nodes such as Ni, Nj, Nk, themselves spaced 200m apart.
• CNT Central Nodal of Transmissions
• IF controlling for example a needle motor
• FIG. 2 we see an embodiment of the antenna of the mobile.
• the production of this antenna is based on the use of a GO slot waveguide such as that used in the IAGO system of ground-train links developed by the company GEC-ALSTHOM, described in particular in the patent.
• French 2,608,119 dated 12.12.86 but, in this system, the waveguide is placed in the track and the train has a point antenna connected to a traditional microwave transceiver).
• the waveguide is in the form of a rectangular extruded aluminum tube, the dimensions of which are of the order of 10.5 cm ⁇ 5.5 cm, pierced with slots f perpendicular to the track, spaced on the order of 4.5cm.
• the waveguide 1 is protected from ballast projections by a steel strip 2 pierced with slots 3 so as not to mask the slots 4 of the aluminum tube and which ensures the fixing of the tube under the body 5 by means of bolts 6, for example, screwed into the body 5.
• the edges of the slits of the strip are bevelled, as shown in FIG. 3.
• l weakening presented by the guide, with its slots is around 18dB / km, or 4dB over the length of the train, and 2dB only if the reader is placed in the middle of the train and feeds two half-guides of a length of 110m each.
• the guide placed under the body of the powerplant or a trailer is rigid.
• the undeformable train is articulated around ball joints usually located just below the intercirculations allowing travelers to pass from one trailer to another.
• Several solutions can be used to connect the waveguides of neighboring trailers.
• FIGS. 4a, 4b and 4c Three of the possible connection solutions have been summarized in FIGS. 4a, 4b and 4c.
• the first of these solutions consists in using a flexible waveguide in the connection area as is encountered in certain radar installations.
• This connection is consists of a flexible part, possibly consisting of two flexible parts s 1 and s 2 separable, connected respectively to the wave guides GO 1 and GO 2 .
• the second of these solutions consists in connecting the two adjacent waveguides GO 1 and GO 2 via a coaxial cable
• each of the opposite ends of the waveguides GO 1 and GO 2 is extended by an aluminum element having the shape of a truncated pyramid, the small base of which corresponds to the section of the waveguides and whose large base is homothetic of it. Given the small clearance between the two ends of the waveguides, the loss of radiation is effectively reduced.
• the referenced patent indicates how it is possible to use a slotted waveguide to safely measure speed. This measure is based on injecting a frequency such that between two successive slits the wave moves about half a wavelength.
• an antenna located a short distance from the guide detects nodes and bellies of amplitude whose count allows it to know the space traveled (and whose quotient of this count by time allows it to know the speed ). This possibility can be exploited by the reader. If, in addition to the frequency close to 2.45 GHz used for the transmission, it injects a frequency close to 2.7 GHz, the signal which is returned to it is modulated with the pitch of the slits.
• a first method would consist in using two readers L 1 and L 2 , which transmit on slightly different wavelengths, so that the signals at various frequencies can coexist without their reception being disturbed. These readers would be on board in 3, corresponding to the middle part of the train. Another would be that the reader is located in the middle of the train at 3 and can transmit as desired through one or the other of the two guides G 1 and G 2 each traversing half of the train. The emission of a short message and the measurement of the quality of the response of one and the other allow the reader to choose one of the two tags
• the preferred method is yet another method. It consists of continuously transmitting on two frequencies close to 2.7 GHz but distinct, so as to obtain at least one of them, because half of the guide in which it is sent covers a beacon, a continuous measurement of speed. It is sometimes the first beacon, sometimes the second, with an overlap during which two beacons are covered and can both provide speed in safety. The observation of the response of a new beacon (and an associated quality measure) makes it possible to decide when to use one or the other of the two waveguides to run the transmissions.
• beacon speed the distribution of beacons along a line, at intervals which allow a high speed bandwidth transmission from one to the other
• the relatively high number of beacons which makes one wish that the communication nodes to which they are attached have a simple structure, the fact that these nodes can also be advantageously connected to fixed installations such as controllers needles or announcement systems at level crossings, are all characteristics specific to transmissions which must link the beacons to the nodal transmission center.
• ground-train communications systems according to the invention are advantageously supplemented by an adapted and specific system for managing terrestrial communications which is in a way the guarantor of performance and its economy.
• a short range microwave transmission can therefore be the "ground-train jump" link in a communications network between a transmission center and all the trains traveling on a line.
• the terrestrial network for connecting the microwave beacons must offer a level of performance compatible with that of the beacons, high availability and moderate cost. It must also be capable of handling other transmissions of interest to fixed points located on the track or in its vicinity: fixed stations of the ground-train radio, motors and needle controllers, passage management systems level, possibly telephone access terminals, etc.
• the speed of the desirable link between a beacon and what we will call the Nodal Transmission Center (CNT) is of the order of 250kbit / s, full-duplex.
• This figure assumes a ground-to-train transmission with a speed greater than 500 kbit / s, because this transmission must be done on a half-day basis.
• the speed must be more than double the speed of the link with the CNT because account must be taken of the exchange of service data between train and beacon, turnaround times, dead times linked to the determination by the train of the beacon to be used when it is above two beacons simultaneously (although the use of two readers or a second frequency used for example for a speed measurement in safety makes it possible to ensure this determination in masked time ).
• the available bandwidths easily allow this speed.
• the consideration which sometimes limits it, namely the economy of a battery which is supposed to last several years, should probably not play a role if the beacons are remotely powered by the connection network.
• the spacing of two consecutive beacons on the same track is 200m.
• 200m is the maximum spacing allowing to ensure the continuity of the coverage to a TGV train of 200m and therefore to offer services which to have a commercial quality requires this continuity, like the telephone.
• Each node must manage 1 beacon (on single track), 2 (on double track) or even more on certain lines or in the station area. It must also manage the connection of neighboring fixed equipment (fixed stations of ground-train radio, needle controllers if they are managed by
• Optical fiber has the advantage of total insensitivity to disturbances and that of high capacity. It has the disadvantage that there are at present only on a relatively low line mileage, although increasing, while copper is widespread. It also has the drawback that its performance in terms of transmission presupposes in practice powerful nodes and which therefore risk being costly.
• the ring must be closed so that the CNT manages both transmission and reception.
• the simplest is that the return path is the same as that of the outward journey, that is to say that the topology is that of a loop borrowing only one line to go and return .
• each node n 3 is connected, in the two directions of transmission, to each of its two neighbors n i and n k .
• the information will only be processed in one direction; the other will be limited to ensuring the function of repetition and reconfiguration.
• Nodal Center of Transmissions This does not mean that, in normal operation, each one must intervene in the connection of a given node but only that it must be possible, in the event of break of the connection, to connect to a CNT all the nodes being on the same side as him of the cut.
• CNT Nodal Transmission Center
• node a step on the terrestrial link, responsible for local transmission, reconfiguration and extraction or insertion of information in the loop,
• the train through its dialogue with the beacon, is capable of having in the node the information making it possible to intercept the information intended for it and to know when and where to inject data supplied by the train.
• connection structure appears to be that of a folded-over ring in which each node was crossed twice, a first time giving the opportunity for logical processing and a second time for the title a simple transmission repeater.
• R 1 , R ' 1 Registers
• R 2 , R' 2 Registers
• FSV FiFo empty output.
• All the nodes are identical. each has 2 inputs EG and ED, two outputs SD and SG and a logic L. It can operate in 4 modes, by calling L the logic part:
• each frame has a synchronization pattern and can include an area carrying an order (we will see more far that this zone can be the first two bytes of the ACS Static Capacity Affection zone).
• the CNT2 will not issue anything at first.
• the CNT1 will continuously transmit a frame comprising only the synchronization pattern and 1s in the rest of the frame.
• the nodes having regained synchronization will remain in mode 1 where they have hung, and this step by step starting with the node closest to CNT1. If the non-hooked nodes switch between mode 1 and mode 4 approximately every two frames, we see that they will hang on the CNT1 at a rate of a little more than one per frame (on average, two in
• n 1 is the number of nodes that we want to manage from the CNTx, we see that after n 1 frames, we are almost sure that the last node to manage, which we will call m, has caught on (if we wait longer, all the nodes between CNT 1 and CNT 2 will eventually hang in mode 1 on CNT 1 and CNT 2 will receive the information sent by CNT 1 ; we could also decide to wait for this moment).
• a frequency of 250 frames / s and spacing 200m nodes, 100 km of line will "hang" in 1.5s.
• the nodes having hooked up the synchronization receive a 1 throughout the part of the frame which is not the synchronization pattern. They therefore receive it in particular in the first two bytes of the ACS Static Capacity Allocation zone which normally designate a node, by a 12-bit number, and a gate of this node, by a 4-bit number.
• the code they receive in this area, 65535 normally designates gate 15 of node 4095 (which must not exist). It will be interpreted as giving the order to stay in the reset mode.
• CNT 1 will then send to node m, named by name, an order to switch to mode 2 (a Static Capacity Assignment defined by its node number and, for example, door number 15).
• the CNT 1 will then receive, by the loop finally closed, the series of information that it sent.
• the reset of the first loop is complete.
• the CNT 2 can then do the same, by sending the initialization pattern on which, step by step, all the remaining nodes will catch on. There is indeed no competition to fear from CNT 1 since node m is looped in mode 2.
• CNT 2 can give the most distant m 'the order to pass through mode 3 (a Static Capacity Assignment defined by its node number and, for example, door number 14).
• the initialization of the second mouth is complete.
• the CNTs can agree to move the border of their respective action zones. Whoever restricts his area of action must do so first, by sending the new last node the loopback code. We will assume that it is CNT 1 .
• the abandoned nodes then pass, at the end of a timer, in the synchronization search mode if n 2 is the number of nodes to be made. go under the authority of CNT 2 , it must go into synchronization mode for a duration of around n 2 frames (the other nodes have not lost their synchronization). It can then send the loopback order to the new last node.
• Frame Synchro and empty FIFO) ST and FSV It therefore in principle comprises 19 wires, which can be reduced to 12 if the data wires are multiplexed.
• the node has known (for some time) the abbreviated train number, which it has assigned to the door through which the beacon is connected.
• the node At the start of each frame (every 4 ms), the node writes to the output FIFO F 1 S the number of the new frame and sends a signal on the Synchro thread
• the beacon When it receives this signal, the beacon knows that the bytes intended for the train in the frame i-1 are in the output FIFO F 1 S, terminated by the additional byte giving the number of the new frame.
• the number of data bytes received by a node during a frame is always equal to the number of bytes transmitted by the node in this same frame. It is therefore known to the tag, which must have noted this number during the previous frame. The tag can "get ahead" in reading the data bytes, by testing the emptiness of the FIFO.
• the beacon is able to transmit to the train, when it interrogates it, the bytes of data received. It must also indicate to the train the number of the new frame, which helps it to keep the synchronization, which need only be approximate.
• the beacon receives the indication of the number of bytes to be transmitted (and the corresponding data bytes) from the train. This number will most often be the same from one frame to another, but nothing prevents it from varying, according to a known law of the train. Transmitting them in time means that they must have been stored in the input FIFO F 1 E before the node has the opportunity to transmit them. As the beacon does not know this moment, it must assume that the transmission begins from byte 64 of the frame, but nothing prevents it from getting ahead.
• a train If a train approaches a new beacon i, it starts a dialogue with it (but up to a certain moment not with the CNT through this beacon). Once the quality of the connection is satisfactory, the train indicates its abbreviated number to the beacon. It also indicates to him from which frame n he wishes to carry out the hand-over, that is to say to use the new tag i for his exchanges with the CNT rather than the current tag j. It indicates it in the i tag but does not care to indicate it in the j tag.
• the tag During the interval corresponding to frame i-1, the tag enters the abbreviated number into the input FIFO F 1 E. Then it sends a signal on the Attention wire A. This causes the abbreviated number to be read. by the node, its copying in the selection register associated with the door as well as in the output FIFO F 1 S. The beacon thus has the opportunity to verify that the abbreviated number has been correctly received and, if not, to pass it on again.
• the train transmits to the beacon i the data to be sent in the frame n.
• the tag enters them into the input FIFO F 1 E which connects it to its node. During the transmission of this frame n, it is again from the tag j that the train must read the data which was intended for it in the frame n-1.
• the input FIFO F 1 E of the latter cannot provide data when the selection mechanism gives it the opportunity.
• the vacuity of the input FIFO F 1 E not only causes the non-transmission and its replacement by the transparent retransmission of the bytes received from the upstream node but also the deselection of the gate, that is to say the resetting to 0 the selection register associated with the door to which the beacon j is connected. The node j has again become available for a next train.
• any underrun has the same effects as ending the use of a tag. We must therefore avoid blocking which would result from the fact that the input FIFO F 1 E may contain the end of the data to be transmitted, which would prevent reinitialization by the train which caused the underrun or initialization by the next train. This is why the underrun must cause, at the start of the next frame, the purging of any FIFO content.
• the train When a quality contact is established with the beacon, the train transmits its abbreviated number and the indication of the frame from which it wishes to transmit (in principle, the following).
• the node knowing the abbreviated number but not having received in the frame an indication of capacity allocated to the train, transmits at the end of the frame a request for allocation of capacity. A certain number of frames will pass before the CNT has received this request, has processed it and decided on an assignment and can indicate it in a frame at the start. Until this time, the node will reissue the allocation request in each frame.
• the number of the frame will be for the train the implicit indication of the number of bytes transmitted and therefore to be renewed.
• the link will have remained inactive only in practice, the physical time of the loop's journey plus a frame duration (or two?).
• a train which does not yet have a short code (because it arrives in the area covered by the CNT without announcement by the CNT that it has left or because it comes out of a period of inactivity) uses as abbreviated number a null value. This is detected by the node when the selection register is loaded and causes it to send to the CNT a message requesting the allocation of a static multiplexing capacity with the train, defined not by the abbreviated number that it has not yet but by the number of the node and the door to which the tag is connected.
• the link thus established is between an addressing and capacity allocation process in the CNT and an initialization process in the train.
• This exchange allows the train to indicate its complete machine number and its capacity requirements.
• the CNT indicates to the train the abbreviated number it must use and the assigned rate (how many times 32 bytes per frame, or in each of the 16 frames of a multiframe if this capacity is not constant).
• the CNT breaks the static link.
• the beacon after having noted this break by the fact that it no longer receives a byte in the output FIFO F 1 S, initializes the dynamic exchange by placing in the input FIFO F 1 E, the abbreviated number of the train and sending the Attention signal to A.
• the deactivation of an abbreviated number is automatic, upon expiry of a delay without transmission (of 5 minutes for example). To avoid an interpretation error, the CNT still waits a certain time before reassigning the same abbreviated number to another train.
• the train may have to ask the CNT to modify the speed (for example due to the appearance of new needs or their disappearance). He must do it through the data flow it sends to the CNT, which it is assumed that a certain subset is intended for link management.
• the CNT can modify the flow by itself, either because of a change in requirements or to distribute the shortage.
• the flow can be made regular by the use of FIFOs; as it is relatively slow, data can be exchanged on a serial link; two sons are enough, one per direction.
• the "fixed" capacity can however be modified by the CNT; the interest is, for example, to test at low cadence the controller of a needle which no train approaches and to increase the cadence when a train approaches ("imperative" control); the node can perfectly be remote-controlled and vary the rhythm of the bit clock that it provides to the connected unit.
• Bytes 0 and 1 contain a synchronization pattern.
• Byte 2 contains a frame number. Only the last four bits are used to define the frame in the multiframe, but all 8 bits are used to distribute a clock with a period of about one second. The frame number is used on the one hand to ensure a sub-multiplexing making it possible to offer low bit rates at certain doors and on the other hand to coordinate the handovers.
• ⁇ Dynamic Capacity Assertment CD (bytes 3- Each of bytes 3 to 30 (byte 31 always contains 0) assigns to a certain train a transmission capacity of 32 bytes in the DMD area of Dynamically Multiplexed Data of the frame.
• the train concerned is designated by a short number, 1 byte, which has been previously assigned to it by the Nodal Transmission Center (CNT).
• CNT Nodal Transmission Center
• the same train can be assigned a multiple capacity of 32 bytes in the frame, which does not does not have to correspond to contiguous zones of DMD It can also have a number of zones which varies from one frame to another but in a manner agreed in advance according to the number of the frame in the multiframe.
• each capacity increment of 32 bytes corresponds to a bit rate increment of 64,000 bit / s.
• the lowest bit rate that can be dynamically assigned is 32 bytes every 16 frames, or 4 kbit / s.
• the highest is 28 ⁇ 32 bytes per frame, or 1,792 Mbit / s.
• Address 0 is never assigned to a train and its use in ACD therefore does not affect a memory area (but it may be the subject of a static assignment).
• a more complex message must in principle be sent individually to each train by the CNT.
• ⁇ CS Static Capacity Assignment (bytes 32-36) This zone allows the modification of the capacities assigned to semi-static multiplexing (DMS zone). Only one capacity can be modified per frame.
• the ACS zone consists of 3 sub-zones: - the first, of 12 bits, designates a node. The nodes have a number fixed in EPROM. Two identical numbers must not be in a line area managed, in normal or in emergency, by the same CNT; the number 4095 is reserved for the reconfiguration mode,
• the third area, 24 bits indicates the bytes affected.
• the first 14 bits designate a byte address in the frame (10 bits) and a frame number in a multi-frame (4 bits).
• the next 9 bits constitute a mask saying which of the last 9 bits of the previous zone do not take into account: the first 5 relate to the last 5 bits of the address zone and the last 4 to the frame number.
• a null mask represents a capacity of 1 byte per multiframe, that is, for a frame frequency of 250, a bit rate of 125 bit / s; a mask of 111 (in binary) represents a capacity of one byte in every second frame, ie a bit rate of 1 kbit / s; a mask of 111111 represents a capacity of 4 bytes in each frame, or a bit rate of 8 kbit / s.
• a value of 0 in the address field removes a previous allocation.
• the first 14 bits designate, with perhaps unnecessary precision as we will see, a byte address in the frame (10 bits), followed by a frame number in the multiframe (4 bits). All the 0's that end the zone indicate how many of the least significant bits among the first 14 ignore.
• the value (expressed in binary) 1100110011010111 affects the address byte 1100110011 in frame 0101, ie a bit rate of 125 bit / s.
• the value 1100110011011100 affects the same address in 1 frame out of 4, i.e. a speed of 1 kbit / s.
• the value 1100110010000000 assigns the 8 address bytes 1100110000 to 1100110111 in each frame, i.e. a speed of 16 kbit / s.
• the nullity of the first 16 bits can be taken advantage of by a node to request a static assignment to one of its dynamic doors, as indicated for the mechanism for assigning an abbreviated number to a train that does not already have one, or even to one of its static doors, as the possibility was mentioned for the connection of telephones .
• This node, noting the nullity of the first 16 bits writes its own number and that of the door concerned in the last 16.
• the mechanism indicated shows that it is the last crossing "which wins”. As a node will send the same request, frame after frame, until it has obtained an abbreviated number for the door in question, this collision has no other drawback than delaying the assignment.
• the Statically Multiplexed Data DMS area is managed according to static or more exactly weakly dynamic multiplexing, the allocation mechanism of which is indicated by the ACS Static Capacity Allocation area.
• individual bit rates can range between 125 bit / s and 64 kbit / s.
• Each bit in this area corresponds to a train, defined by its abbreviated number.
• the CNT initially sets the entire area to 0.
• Each node crossed can set certain bits to 1, but not 0 (i.e. each node transmits downstream the logical fusion of what it received from upstream and what it has added). It puts at 1 the position corresponding to a train of which one of its doors includes the abbreviated number in its selection register if, for this train, it was not unable to provide the bytes requested through the ACD area. In other words, it puts a 1 for a train which has provided all of the requested bytes or for which no transmission capacity has yet been allocated.
• bit rate is subject to change. For example, if the door corresponds to a needle controller, a control center can request, when approaching a train, a speed of 4 kbit / s and be satisfied, at other times, with a speed of 125 bit / s.
• 8 wires of Data In and 8 wires of Data Out can be replaced by 8 wires of Data, bidirectional, and a direction selection wire, managed by the connected device.
• a parallel interface seems preferable to a serial interface, both because the short distances between beacon and node allow it (a few meters) and that it seems interesting to reduce the flow, this one being able to be high, the environment electrically polluted and the mode of transmission should be kept simple.
• the architecture of the node can be broken down into a certain number of common organs, ensuring the following functions:
• the node has 2 inputs EG and ED and two outputs SD and SG and it can operate in 4 modes depending on the position it occupies in the loop considered.
• the reconfiguration unit ensuring the functions described above comprises only the electronic relays ensuring the contacts corresponding to the four modes. It is the BT time base which must search for synchronization, send the code ordering the switchover in modes 1 and 4 alternately (with a period for two half-waves corresponding to the duration of approximately 4 frames) as long as it does did not find the sync, inhibit any program other than a repetition as long as it recognizes the OFFFF code
• the overall performance of the loop is partly linked to the crossing time of each node. It seems impossible to go below a bit time but it is desirable not to go above it, in particular not to add a time-byte.
• the BT time base has multiple functions:
• Dynamic capacity management involves writing and reading the FGD dynamic management FIFO.
• This FIFO is filled, from bytes 0 to 31 of the frame
• each non-zero byte represents the abbreviated number of a train authorized to use the group of 32 bytes corresponding to its rank in the FIFO to receive and transmit data. Consequently, each byte of the FIFO is presented, for 32 consecutive byte times, on the address bus BA (where it is multiplexed with the bit time and the frame number) and it is the dynamically managed gates which compare in C 1 and NA the abbreviated train number presented to the one entered in their assignment register. In the event of a match, at each byte time, they read a byte in the input FIFO F 1 E and write one in the output FIFO F 1 S.
• the management of the static capacities and of the rhythms managed by RS is done by the comparison in C 2 of the byte time (and frame number) presented on the address bus BA and of what the door has stored as control information, namely the same kind of information, plus a mask explaining which bits to ignore in the comparison.
• This ordering information was presented in series, and stored in parallel in a 24-bit register. Data transfers could also be done in series.
• the gate Ps also includes a selector making it possible to choose which of the wires of the address bus BA to be used to give the rhythm to the external serial link, regular rhythm even if the data arrive in packets.

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• 1991
  • 1991-04-24 FR FR9105045A patent/FR2675761B1/fr not_active Expired - Fee Related
• 1992
  • 1992-04-23 ES ES92401156T patent/ES2106841T3/es not_active Expired - Lifetime
  • 1992-04-23 JP JP4510450A patent/JPH06506810A/ja active Pending
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  • 1992-04-23 CA CA002108755A patent/CA2108755A1/fr not_active Abandoned
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  • 1992-04-23 EP EP92910371A patent/EP0581847A1/de active Pending
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• 1997
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