Abstract:
A communication circuit for use within a vehicle includes a first network port and a second network port that is remotely located from the first network port. The networks are digitally connected together and digitally communicate a high speed multimedia signal therebetween, via a digital link adaptive to impairments thereof. The communication circuit is used between two or more coupled train vehicles.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a Continuation-In-Part (C.I.P.) of co-pending non-provisional patent application, Ser. No. 10/667,423, filed on Sep. 23 rd , 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention concerns communication networks and more particularly to a digital system for transmitting bi-directional multi-media and data signals within and between train vehicles, via a digital link adaptive to impairments thereof.  
       BACKGROUND OF THE INVENTION  
       [0003]     Communication systems are well known and widely used in the transportation industry. For applications such as intra and inter vehicle communications on board articulated vehicles such as trains and the like, communication systems typically include a number of electrical large cables that transfer data signals between audio and visual components between train vehicles. Typically, the train operator relays messages from the train cab via the audio and visual components to the passengers and often to another train operator who may be located remotely from the train cab. This type of communication, while straightforward, suffers from a number of significant problems. The electrical cables are often cumbersome to handle and connect and are prone to damage by the train&#39;s articulated sections. The audio and visual components often require rebooting after a connection has been made, which may delay the train&#39;s entry into service. The harsh environments in which the electrical cables are used often hinder the transmission of fast, high quality data. This is particularly problematic in subway trains, where high temperatures, electromagnetic fields and vibration cause signal interference. Additional components may be added to the network, but this often requires separate and additional cables to be connected, which in turns adds to the size of the cable bundle between the train vehicles.  
         [0004]     In an attempt to overcome some of the aforesaid problems, the Institute of Electrical and Electronics Engineers (IEEE) has issued standard IEEE-P-1473 (Standard for Communications Protocol Aboard Trains) defining two digital networks for rail transit applications that are present in today&#39;s train vehicles. These networks do not, however, provide the data bandwidth necessary for multimedia communications, especially between connected train cars. Other control and communication networks for use between connected train cars are available with existing analog-type technology, but are complex to connect, and do not provide the versatility of a digital solution.  
         [0005]     A digital network that enables, for example, passenger communication to a train driver or communication between two drivers located at different locations in the train, while simultaneously conveying playing audio messages, advertising, and displaying information on in-train screens, would be a significant improvement in the train industry. Moreover, for ease of use, the network should be designed with few space conserving connections, while allowing easy upgrades or addition of new communicational units as they become available.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention reduces the difficulties and disadvantages of the prior art by providing an Internet Protocol (IP) network or circuit that allows integrated high-speed multimedia digital communication between Local Area Networks (LANs) such as passenger information system including audio and visual message announcements, maintenance and diagnostics networks, video surveillance networks, propulsion data networks and the like, located within or between train vehicles. A novel redundant multimedia high speed digital link is provided, which connects the LANs and the train vehicles together and communicates the data therebetween via a Wide Area Network (WAN) backbone connection interface. Advantageously, the LANs are used to transmit bi-directional multimedia and data signals at high speed to the remote locations in the train while significantly reducing or essentially eliminating the aforesaid problems of poor quality reception and transfer of data. In addition, the circuit uses well-established ETHERNET™ technology and provides multiple ports to attach peripheral devices thereto. The single digital link is easy to connect between train vehicles and is significantly user-friendlier than the aforesaid connections. In addition, the IP network supports different data links and physical layer technologies, such as Wireless Local Area Network and the like. The IP network provides static and dynamic mobility that enables operation during a train&#39;s travel and during the interchange of cars, without the need to reboot the system network. The network has a reliable open architecture that is easy to upgrade by adding or withdrawing new or existing network communication devices such as, for example, video monitors and the like. Moreover, the network is adaptable to the type of environment associated with trains, buses, subways, trams and the like, and reliably operates where high levels of vibration, temperature, and electromagnetic fields occur. Furthermore, the digital link is dynamically adaptive to circuit impairments to keep the multimedia high speed connection through all interfaces.  
         [0007]     In accordance with an aspect of the present invention, there is provided a communication circuit for use within a vehicle, the circuit comprising: a first network port; and a second network port located remote from the first network port and digitally connected thereto for digital signal communication therebetween, the first and second network ports are connected by a digital link being adaptive to impairments thereof.  
         [0008]     Preferably, the first network port and the second network port are connected by a digital link.  
         [0009]     Preferably, the first network port is connected to a first network segment and the second network port is connected to a second network segment. Conveniently, a third network segment is connected between the first network segment and the second network segment.  
         [0010]     Preferably, each network segment includes a multi-port network hub, the first and second network ports being connected to their respective multi-port network hubs. Conveniently, at least one peripheral network communication device is connected to each of the multi- port network hubs. Conveniently, at least one of the peripheral devices is a control head. Conveniently, at least one peripheral communication device is connected to the control head. Each multi-port network hub is a multi-port ETHERNET™ network hub.  
         [0011]     Preferably, the first, the second and the third network define a first Local Area Network. The first, second and third network segments are respectively first, second and third Local Area Network subsystems.  
         [0012]     Conveniently, the digital link is an ETHERNET™ digital link.  
         [0013]     Preferably, a train includes at least two vehicles connected together by a coupler, the first Local Area Network being located in one vehicle, a second Local Area Network being located in the other vehicle. Conveniently, the first Local Area Network includes a first interface and the second Local Area Network includes a second interface.  
         [0014]     Preferably, the first interface is a control unit having a digital link receiver port and a wire connector connected to the first network port.  
         [0015]     Conveniently, at least one of the vehicles is sectioned and articulated. Conveniently, the coupler includes a digital link integral therewith.  
         [0016]     Conveniently, the digital link dynamically adapts to the impairments thereof, and has a signal transmission baud rate greater than about 40 Mbps.  
         [0017]     Preferably, the digital link is an ITU G9954 multimedia high speed Wide Area Network backbone connection. Conveniently, the control unit includes a plurality of peripheral device connector ports.  
         [0018]     In accordance with another aspect of the present invention, there is provided a communication circuit for use on board a train having at least two vehicles coupled together, the circuit comprising: a first Local Area Network having a first interface and located in one vehicle; a second Local Area Network having a second interface and located in the other vehicle; and the first interface and the second interface being connected by a digital link adaptive to impairments thereof for digital high speed signal communication between the first and the second Local Area Networks.  
         [0019]     Other objects and advantages of the present invention will become apparent from a careful reading of the detailed description provided herein, within appropriate reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Further aspects and advantages of the present invention will become better understood with reference to the description in association with the following drawings, in which:  
         [0021]      FIG. 1  is a schematic view of two train vehicles with a multimedia high speed digital connection therebetween; and  
         [0022]      FIG. 2  is a schematic diagram illustrating an embodiment of a circuit for communication on board a train. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     Referring now to  FIGS. 1 and 2 , a first train vehicle is illustrated generally at  10  and is subdivided into three articulated car sections  12   a ,  12   b , and  12   c . A second train vehicle  14 , which may also be articulated and sectioned, is connected to the first vehicle  10  by train couplers  18 ,  18 ′. One skilled in the art will recognize that that although the illustrated embodiment is a train, the present invention can also be used with other ground-based vehicles without deviating from the scope of the invention. Broadly speaking, the first train vehicle  10  includes an embodiment of an IP network or circuit for integrated communication on board a train in accordance with the present invention. The circuit includes a first Local Area Network (LAN)  20  that is connected to a second LAN  21  located in the second train car  14  via a digital ITU G9954 multimedia high speed train coupler link  24  for communications between the two train vehicles  10 ,  14 . This establishes a bi-directional and transmission of an ITU G9954 multimedia high speed digital signal between the two train vehicles  10 ,  14 . For communication between the LANs segments located within each of the train vehicles  10 ,  14 , an ETHERNET™ digital link is used. Both the LANs are preferably based on ETHERNET™ technology as will be described below.  
         [0024]     The ITU G9954 multimedia high speed digital train coupler link  24  may be made out of two twisted pairs of wires. Preferably, one shielded twisted data pair of wires and a single reference wire are used, which are compliant to the ITU G9954 specifications and which can easily be plugged or unplugged between the train vehicles  10 ,  14  and links together the two LANs  20  installed in each train vehicle  10 ,  14 , respectively, enabling high speed audio and video communications greater than about 40 Mbps (Megabit per second). As readily understood by those skilled in the art, ITU G9954 data layer technology provides proven bi-directional communication capabilities with discriminative signal that ensures data integrity within the harsh EMI/EMC (Electromagnetic Interference/Electromagnetic Compatibility) environment of a train.  
         [0025]     Referring specifically now to  FIG. 2 , a control unit  22  is used for the LAN  20 , and provides an interface to another LAN  21  of the train vehicle  14  with the ITU G9954 multimedia high speed digital train coupler link  24  connected from the control unit  22  to the train coupler  18 . The ITU G9954 multimedia high speed digital train coupler link  24  is connected at both ends of the train car  10 . A number of communication busses, links, or peripherals  26  such as an RS-232 connector, a Multi-Function Vehicle Bus, a LONWorks, a CAN bus and an Integrated On-Board Information System are connected to the control unit  22 . One skilled in the art will recognize that the interface may include a gateway or conversion circuit between the LAN interfaces (or ETHERNET™ link) and the ITU G9954 multimedia high speed digital link for inter-vehicle transmission. Additional busses, links, or peripherals  26  that do not support an Ethernet network interface may also be connected to the LAN  20  through the control unit  22  or through other interface devices. The ITU G9954 multimedia high speed digital link  20  provides for a Wide Area Network (WAN) backbone connection that implements the concept of Quality of Service (QoS) to guarantee data packet delivery of sensitive propulsion and diagnostic data.  
         [0026]     The LAN  20  is divided into LAN subsystems  28   a ,  28   b ,  28   c , which are located in each car section  12   a ,  12   b ,  12   c , respectively of the first train vehicle  10 . Similar LAN subsystems may also be located in the second train vehicle  14  and connected together using the digital link  24 . Each LAN subsystem  28   a ,  28   b ,  28   c  includes a multi-port ETHERNET™ network hub  30   a ,  30   b ,  30   c , respectively. The multi-port ETHERNET™ network hubs include a number of network ports, which are particularly well suited for the present invention since they reduce unnecessarily complex wiring across the articulated joints  13  that separate the car sections  12   a ,  12   b and  12   c  in an articulated train vehicle. One network segment may have a network port connected thereto and located in one section of the vehicle  10 ,  14 , while another second network port may be connected to a network segment located in another section of the vehicle  10 ,  14 . The control unit  22  is connected via wires  31  to the multi-port ETHERNET™ network hub  30   a , which in turn is connected via wires  31  to the multi-port ETHERNET™ network hubs  30   b ,  30   c  to ensure ETHERNET™ communication network interconnections. A number of peripheral devices  26  such as control heads  32   a ,  32   b  to allow an operator control of the network, emergency intercoms  34   a ,  34   b , public address amplifiers  36   a ,  36   b , and sign units  38   a ,  38   b ,  38   c  are connected via wires  31  to corresponding multi-port ETHERNET™ network hubs  30   a ,  30   b ,  30   c  to ensure ETHERNET™ communication network interconnections. Additional multi-port ETHERNET™ network hub(s)  30   a , control head(s)  32   a , emergency intercom(s)  34   a , public address amplifier(s)  36   a , sign unit(s)  38   a , and other peripherals  26  may be added or removed depending upon the requirements of the train vehicle  10 , provided that sufficient network ports are available in the multi-port ETHERNET™ network hub(s)  30   a  for interconnection in-between. For practical reasons the length of the ITU G9954 multimedia high speed digital link  20  is dependent upon the rate of data transmission and the quality of the coupling connections. A laptop computer or the like may be connected to any available ETHERNET™ hub to set, verify, and upgrade the LAN  20  and/or the IP protocol as required.  
         [0027]     Each control head  32   a ,  32   b  in conjunction with a console  39 , a handset  41 , and a speaker  40  provide the audio and control interfaces between the train operator, located in any train vehicle  10 ,  14  of the train, and the LAN IP network  20  for integrated communications. A radio system, or handsets  42   a ,  42   b , and speakers  40  are connected via wires  31  to the control heads  32   a ,  32   b  for security reasons. Each emergency intercom  34   a ,  34   b  provides a two-way full duplex audio communication between the passengers and any train operator using built-in microphone(s) and speaker(s) (not shown). A push-to-talk switch (not shown) on the handset  41  enables a train operator to control the direction of the communication. The public address amplifiers  36   a ,  36   b  provide a one-way audio communication for a public pre-recorded or live announcement to passengers by means of interior and exterior speakers  40 . Microphones  42  are used to measure ambient noise and are connected via wires  31 . The ambient noise is sampled to permit the public address amplifiers to automatically adjust the volume. The sign units  38   a ,  38   b ,  38   c  broadcast through visual front destination signs, run number signs, side destination signs and interior message signs (not shown) various messages to inboard and outboard passengers.  
         [0028]     A software program (not shown), implementing a Plug-and-Play architecture, controls the LAN  20  combined with the ITU G9954 multimedia high speed digital link  24 , and allows for connection and/or voluntary or involuntary disconnection of a multi-port ETHERNET™ network hub  30   a , control head  32   a , emergency intercom  34   a , public address amplifier  36   a , sign unit  38   a , or other peripherals  26  without interrupting the functioning of the LAN  20 . The high mobility of interconnected LAN  20  is furthermore shown by the fact that the LAN  20  is understandably operational during the traveling of the train vehicles  10 ,  14 , but is also demonstrated by the operation of the LAN  20  during the connection and/or disconnection of the train vehicles  10 ,  14 , without having to reinitialize any part of the LAN  20 . Other systems not described herein are incorporated into the software program, such as a network health monitoring system or the like verifying the conditions and functionalities of the LAN  20 . Each control unit  22 , multi-port ETHERNET™ network hub  30   a ,  30   b ,  30   c , control head  32   a ,  32   b , emergency intercom  34   a ,  34   b , public address amplifier  36   a ,  36   b , or sign unit  38   a ,  38   b ,  38   c  is powered by a main low voltage power supply (not shown) via a pair of wires (not shown), which may be optionally twisted. Individual power supplies could also be considered without departing from the scope of the present invention.  
         [0029]     One skilled in the art will readily recognize that the IP network or LAN  20  of the present invention could support different data link and physical layer technologies, such as Wireless Local Area Network or the like, which would be a preferred alternative especially for the link in-between train couplers  18  and  18 ′.  
         [0030]     The multimedia high speed backbone network also provides a fully adaptive physical interface (or auto-adaptive or dynamically adaptive link) to optimize for return loss and reflection loss due to uncontrolled cable characteristics or cable (or link) impairments, such as using digital processors with algorithms and the like.  
         [0031]     Furthermore, any network subsystem connected to the master ITU G9954 high speed communication link via its network port can be based on its own communication bus, different or not than the others, and could be any already existing network subsystem that would therefore be integrated with all other connected subsystems for communication therewith.  
         [0032]     While a specific embodiment has been described, those skilled in the art will recognize many alterations that could be made within the spirit of the invention, which is defined solely according to the following claims.