FR2523384A1 - OPTICAL FIBER DATA TRANSMISSION INSTALLATION - Google Patents

Abstract

THE INVENTION CONCERNS DATA COMMUNICATION FACILITIES. IT RELATES TO A DATA TRANSMISSION INSTALLATION IN WHICH AN INTERFACE UNIT 17 TO A PATH 18 WITH FIBER OPTICS WHICH JOINS A TRANSDUCER TRANSDUCER 32 AND A RECEIVER TRANSDUCER 31. THE ELECTRIC SIGNALS ARE TRANSFORMED BY A CONTROL CIRCUIT 34 AND CAN COMMUNICATE WITH THE COMMON LINE 10 VIA CHANNELS 35 AND 36. THE CONTROL CIRCUIT 34 FORMS A RECONSTRUCTED SIGNAL INTENDED TO REINFORCE THE SIGNALS TRANSMITTED BY THE COMMON LINE 10. THIS IS CONTINUOUS. APPLICATION TO OPTICAL LINE DATA TRANSMISSION SYSTEMS.

Description

The present invention relates to transmission installations of

  data and especially those in

  which data is transmitted by a common line

mune of optical type.

  The transmission of data takes place in a communication installation when information, coded in the form of a signal, is transmitted from a first node

  communication and is received at a second communication node.

  The use of the technique of trans-

  data mission by a common line in which all communication nodes are connected to a continuous channel In this technique, the communication between all

  connected nodes is possible, provided that precau-

  appropriate conditions allow the determination of the non-encom-

  of the common line, and this determination is made at a receiving node only on the data intended for that node. The use of a common data line

  has a number of advantages, since communication

  cation between several nodes is ensured, and a drawing

  complicated interconnection between the nodes is avoided.

  This technique is particularly interesting when the installation of the apparatus must be carried out in difficult circumstances and in a small space, and when the weight must be minimal, for example in

an aircraft.

  The technique implementing such a common line of data has been developed and is widely used in cases where the coded signal is in electrical form and has facilitated the realization of installations in

  which some processing energy is available.

  communication hubs, without the need for a special central processor. In this way, the number of data transmissions is reduced so that

  the efficiency is increased, but the installation as a whole

  ble is vulnerable to communications failure.

  Recently, a great deal of activity has been devoted to communication links in which data

  are encoded on an optical signal transmitted

  The use of such optical optics

  ticks has particular advantages since the

  data are not likely to be disturbed by

  electromagnetic sites and such optics have mechanical and bandwidth advantageous properties Unfortunately, fiber optics can not be directly connected to a common data line because signal energy losses

  at the junctions of the connections formed at the nodes

  cation accumulate and actually prevent the connection of an interesting number of nodes. A discontinuous common line is used in which conventional fiber optical links are made between nodes and a received signal is regenerated in the next link by a repeater. so that the continuous common line configuration is restored approximately This provision can

  be totally out of effect by the failure of a receiver-

  repeater, so we have to use redundant links

  between at least some alternate nodes so that the consequences

  possible failure may be reduced.

  The invention relates to a transmission installation

  data link comprising a fiber-optic common line for connection between communication nodes and a plurality of coupled interfaces,

  at least one at each node, each having a transducer

  receiver and a transmitter transducer, the transduc-

  are intended to provide communication between the nodes; each interface has a control circuit intended

  to detect a data signal transmitted by the line com

  mune and to transmit it in a constructive way so

  that the data signal is reinforced.

  Preferably, each interface comprises a fiber optical path, starting from an access coupling to a star point and ending in a transmission termination and a receiving termination in optical contact with the

  emitter transducer and the respective receiver transducer

  The transducers can advantageously be mounted in a separate interface unit, connected to a first interface unit by conventional links.

fiber optic.

  Other features and advantages of the

  will become apparent from the following description,

  made with reference to the accompanying drawing in which

  FIG. 1 represents a transmission installation

  data mission according to the invention; and Figure 2 shows in more detail an interface

  intended for the installation of FIG.

  In a data transmission installation (FIG. 1), a common optical fiber line 10 provides communication between several nodes such as the nodes.

  11, 12 and 14 At each node, an interface allows the con-

  connection of a communication apparatus via an input channel and an output channel such as the input and output channels 15 and 16 Each interface comprises a first unit, for example 17, and a second such as 25, and an access connection is formed with the common line 10 (as shown more clearly in the figure

  2 to which reference is now made).

  The first interface unit 17 has a continuous path 18 formed by an optical fiber, which is

  coupled so that he has access to the common line 10 of

  The fiber-optic path 18 has a star-shaped point 20 which forms shunts 21 and 22 which terminate at terminations 23 and 24. The fabrication and properties of a coupling or coupling

  access and a star point are known in the art.

  that, and those skilled in the art can note that the optical signals introduced by the termination 23 are bidirectionally transmitted in the common line 10, and that part of the energy of the optical signals transmitted by the common line 10, in one direction or in the other, arrives

at the end 24.

  The terminations 23 and 24 are coupled to a second interface unit by conventional bidirectional links 26 and 27 to optical fiber, joining terminations 28 and 29 respectively. An optical fiber path 30 transmits the optical signals received by the termination 29 to A photodiode receiving transducer 31 Optical signals from a light emitting diode transmitter 32 are transmitted to the

  terminating 28 by a fiber optic path 33, permitting

  bi-directional transmission via the common line 10 as previously described, so that the data can be transmitted to the other communication nodes via the common line 10 or can

to come from the same line.

  The second interface unit comprises a control circuit 34 for accepting an electrical signal at an input point and for controlling the transducer.

  transmitter 32 so that it emits a corresponding optical signal.

  The control circuit 34 forms an electrical signal

  output at a point 36 of output, corresponding to the

  Optical signals received by the receiver transducer 31.

  In addition, the control circuit 34 is intended to detect a data signal transmitted by the common line 10 and received by the transducer 31, and to trigger the transmitting transducer 32 so that it emits a reconstructed signal

which reinforces the data signal.

  It should be noted that the energy loss exhibited by the data signal when a portion of the energy is transmitted to the interface at the access coupling 19 is compensated by the intensifying emission so that any number of interface circuits may be connected to the common line, without the risk of disturbance of the communication due to energy losses at the couplings (Figure 1). It should be further noted that the common data line 10 is continuous and, provided that a suitable excess of energy is present in the signals, the transmission of the data is not disturbed by the failure of an interface, because the communications are possible between the nodes which continue to function, even in the most troublesome case in which adjacent interfaces are down As the emission provided by an interface is bidirectional, a break of the common line 10 can also be compensated without the transmission of

data is disturbed.

  In the embodiment considered, only one

  fiber optic link forms the common line 10.

  The signals of this common line may have a format

  In the case of analogue or digital

  logic, the emission by reconstruction is an amplified version of the received signal In the case of the use

  of digital format signals, this program is

  in the form of a standardized digital pulse

  so that the noise signals are regenerated by reinforcing

  with the normal impulse when passing through an inter-

  Several fiber-optic analog links and several interfaces can be connected in parallel so that para- lel data transmission is facilitated or the fault tolerance of the system is eliminated.

be improved.

Claims (6)

  1 Data Transmission Facility, Characteristics   in that it includes a common line '(10) to   fiber, intended to be connected between communication nodes (11, 12, 14) and several access-coupled interfaces at least one at each node, each interface having a receiver transducer (31) and a transmitter transducer (32), the transducers being intended to provide communication between the nodes, each interface having a control circuit 34 for detecting a data signal transmitted by the common line and for transmitting a reconstructed signal for reinforcing the signal of data.   2 Installation according to claim 1, characterized in that each access coupled interface comprises a path (18) fiber optic joining a star point (20) and ending in a transmitting termination   (21) and at a receiving end (22) in optical contact   only with the transmitter transducer (32) and the transducer receiver (31) respectively.   3 Installation according to claim 2, characterized in that, at each interface, the transmitter transducer (32) and the receiver transducer (31) are mounted in a second interface unit (25) and are coupled to the transmission termination and at the receiving end   by conventional fiber optic links (30, 33).   4 Installation according to any one of the   cations 1, 2 and 3, characterized in that the interfaces are bidirectionally coupled.   Installation according to any of the claims   cations, intended to operate in analog form, characterized in that the reconstructed signal   for the broadcast is an amplified version of a received signal.   Installation according to any one of the claims   cations, comprising a parallel common line of data, characterized in that it comprises several interfaces to each node.