Abstract:
A system and method for utilizing antenna diversity inherent in a locomotive consist is disclosed. This system increases the probability of message reception from an EOT unit and minimizes LCU failure limitations. The method includes the steps of (a) receiving an EOT message at a trailing locomotive; (b) passing the EOT message to a lead locomotive LCU; and (c) accepting the EOT message at the lead locomotive LCU only if the lead locomotive LCU has not already directly received the EOT message from the EOT unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a system and method for improving End-of-Train (EOT) communications and, more particularly, for using locomotive consist communications to improve transmission and receipt of messages to and from an EOT device. 
         [0003]    2. Description of Related Art 
         [0004]    Typically, an End-of-Train device (EOT) communicates with a lead locomotive using two-way radio data communications. The communications device for facilitating communications in the locomotive includes a locomotive cab unit (LCU). 
         [0005]    Standardized data communications from the EOT to the LCU includes transmission of messages relating to brake pipe pressure, motion status, other status messages and unit ID. For example, brake pipe pressure data may be transmitted when there is a change of at least 2 psi, or nominally at one minute update intervals. Motion status data may be transmitted when there is a change in movement that is detected at the EOT. Unit ID data is included in every message to provide a unique identifier with respect to the other transmitted data. Standardized data communications from the LCU to the EOT include transmission of messages relating to brake application requests, linking procedures and communications requests. For example, brake application requests include emergency or service braking EOT valve operation. Linking procedure messages may be used to set up an EOT ID for control by one specific train. Communications requests may be used by a locomotive to initiate a request for EOT data updates. 
         [0006]    Prior art data radio links are established between the EOT and the LCU in the lead locomotive. The EOT data received by the lead locomotive is displayed to an engineer and is utilized in standard train operating procedures. Communications continuity may be challenging due to the train length position of the EOT antenna and terrain conditions. Typically, no direct line-of-sight exists for radio signal propagation. Therefore, successful communications normally depend upon reflection of signals from the surrounding terrain. As is the case with typical mobile data radio communications environments, multiple reflections of signals can create null points where the signals are lost, depending upon the location of a receiver antenna. 
         [0007]    To accommodate some loss of data radio messages, EOT systems are designed to repeat important messages. However, the number of messages that are repeated needs to be balanced against the risk of creating channel congestion. This is especially true in light of a common set of radio channels being shared for EOT operation, which causes an EOT operating within the vicinity of other EOTs to operate in parallel therewith within the same radio range. 
         [0008]    It is, therefore, desirable to overcome the above problems and others by providing a system and method for improving the reliability and efficiency of EOT system communications. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to a system and method of improving EOT communications and reliability by utilizing a locomotive consist communications (LCC) network with LCU devices in various locomotives of a locomotive consist (i.e., locomotives at a head of a train). Normally, a data radio link is formed only between the EOT and the LCU in the lead locomotive. The present invention utilizes the diverse antenna locations (e.g., lead and trailing locomotives have LCUs) to increase the probability of message reception. This overcomes geographic and LCU failure limitations. Accordingly, system reliability is increased. The present invention is implemented as follows. Timing slots are assigned to each trailing LCU to avoid message collisions when broadcasting repeat messages to the EOT. All LCU devices in each consist are set to receive messages, and the trailing units are configured to repeat any received messages to the lead locomotive. The lead LCU will act on its own upon directly receiving a message from the EOT. However, if the lead LCU does not receive the message, but instead receives a message from one of the trailing LCU devices within a set time frame, then the repeated message will be used instead. Lead LCU initiated penalty brake messages are communicated to the trailing LCU devices, which then broadcast the penalty brake messages according to predefined intervals. 
         [0010]    The present invention provides the benefits normally associated with use of multiple receivers with diverse antenna locations, when in fact only one radio per locomotive is used. EOT transmissions may be received with multiple, diverse location antennas and receivers. Because trailing locomotives are closer to the EOT than is the lead locomotive, the probability of message reception is improved. Also, locomotive-to-EOT critical data communications (e.g., penalty brake commands) are more reliable when multiple trailing locomotives are used due to the diversity of hardware associated with the locomotive consist. Therefore, failure or poor performance of any transmitter within the locomotive consist would not preclude messages from being transmitted to the EOT. Safety regulatory and railroad internal safety rules may force reduction of train operating speeds when EOT communications are reduced or fail. Improving system reliability will reduce the occurrence of EOT failure-related operating restrictions. The present invention does not require any changes to be made to the EOT, to the device operation, or to the logic (as established in North American standards) to gain the aforementioned performance improvements. The present invention also supports the shared use of LCC networks for EOT enhancement. 
         [0011]    Still other desirable features of the invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description, taken with the accompanying drawings, wherein like reference numerals represent like elements throughout. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a diagram illustrating the entities and communicative connectivity therebetween in a system for improving EOT communications in accordance with the present invention; and 
           [0013]      FIG. 2  is a flowchart setting forth the basic steps of the transmission of data between locomotive consists and an EOT device in the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    The present invention will now be described with reference to the accompanying figures. It is to be understood that the specific system illustrated in the attached figures and described in the following specification is simply an exemplary embodiment of the present invention. 
         [0015]    With reference to  FIG. 1 , the present invention is disclosed in connection with a train  10 . The train  10  normally operates with multiple locomotives, such as a first locomotive  12 , a second locomotive  14  and a third locomotive  16 , all situated at the head of the train  10 . The first locomotive  12 , the second locomotive  14  and the third locomotive  16  collectively form a locomotive consist  18 . The locomotive consist  18  includes a lead locomotive, which is the first locomotive  12 , and trailing locomotives, which are the second locomotive  14  and third locomotive  16 . The locomotive consist  18  is connected to any number of intermediary rail cars  19 . A remote unit  20  is situated at the end of the train  10 . 
         [0016]    Each of the locomotives  12 ,  14 ,  16  generally includes a cab for housing related control and communication components responsible for the operation of the train  10 . Specifically, the cabs of the first locomotive  12 , the second locomotive  14  and the third locomotive  16  each have integrated therein a first LCU  22 , a second LCU  24  and a third LCU  26 , respectively. Each LCU (also known as an integrated cab computer) or similar hardware is configured to provide interaction with the communication components of the train  10 . One such communication component is a transmitter (or transceiver) that is communicatively connected to the LCU. For example, the first LCU  22 , the second LCU  24  and the third LCU  26  are connected to a first transmitter  32 , a second transmitter  34  and a third transmitter  36  (or transceivers), respectively. Each transmitter is configured to send and receive data; namely, messages (e.g., LCU messages). 
         [0017]    There are a variety of ways to establish data communications links, known as locomotive consist communications (LCC), between the locomotives  12 ,  14 ,  16 . Examples of LCCs include (a) the addition of powerline communications as an overlay to existing multiple unit (MU) cabling, (b) the addition of a separate cable or trainline for data communications, and (c) separate data radio links between locomotives. Accordingly, a suitable LCC network  38  is established between the locomotives  12 ,  14 ,  16 . However, these examples are not to be construed as limiting the invention. All of these implementations of an LCC network may provide similar capabilities, the most important of which is to allow the lead locomotive, i.e., the first locomotive  12 , to send and receive data from selected trailing locomotives, e.g., the second locomotive  14 , or all trailing locomotives, e.g., the second locomotive  14  and the third locomotive  16 . 
         [0018]    The remote unit  20  is generally associated with a last unit, rail car caboose, or similar nomenclature, at the rear of the train  10 . The remote unit  20  has an End-of-Train unit (EOT)  40  associated therewith. The EOT  40  is generally configured to gather traditional EOT data. Although the EOT  40  is shown in connection with the remote unit  20 , the EOT  40  may be associated with any one of the cars  19  or other rail vehicles that are situated near the rear of the train  10 . The EOT  40  includes a transmitter  42  (or transceiver) communicatively connected thereto. Desirably, the transmitter  42  is configured to send and receive data (e.g., EOT messages). As is known in the art, each EOT  40  has a unique EOT ID associated therewith. 
         [0019]    A method for improving EOT system communications reliability utilizing the aforementioned communicative entities will now be discussed. With continuing reference to  FIG. 1 ,  FIG. 2  depicts a flowchart for illustrating the major steps in implementing the present invention. 
         [0020]    First, as is known in the art and will not be specifically discussed herein, EOT setup and arming thereof is initiated, as shown in block  50 . Thereafter, as shown in block  52 , the lead locomotive, via the corresponding LCU, communicates with any other LCUs of trailing locomotives within the same consist to advise these LCUs of the EOT ID of the EOT  40 . For example, the first LCU  22  of the first locomotive  12  communicates with the second LCU  24  and the third LCU  26  of the second locomotive  14  and the third locomotive  16 , respectively, via the LCC network  38  to pass along the EOT ID of the EOT  40 . 
         [0021]    Next, if more than one trailing locomotive is present in the locomotive consist, a “sequence number” is assigned by the LCU of the lead locomotive to define timing slots to avoid message collisions when broadcasting repeat messages to the EOT  40 , as shown in block  54 . For example, the locomotive consist  18  shown in  FIG. 1  includes more than one trailing locomotive; namely, the second locomotive  14  and the third locomotive  16 . Therefore, the first LCU  22  assigns a different “sequence number” to the second LCU  24  and the third LCU  26 . Accordingly, the second LCU  24  and the third LCU  26  will not transmit when the first LCU  22  transmits. Similarly, the first LCU  22  and the third LCU  26  will not transmit when the second LCU  24  transmits. In essence, a transmitting order is established among the first, second, and third LCUs  22 ,  24 ,  26  to avoid message collisions when repeated messages are transmitted to the EOT  40 . 
         [0022]    The locomotive consist is configured to receive messages, as shown in block  56 . For example, the first LCU  22 , the second LCU  24 , and the third LCU  26  of the respective locomotives  12 ,  14 ,  16  are configured to receive messages. However, no configuration changes are made to the EOT  40 . Accordingly, EOT-initiated communications remain the same. 
         [0023]    Each trailing locomotive is configured to forward received messages, as shown in block  58 . For example, the second LCU  24  and the third LCU  26  are configured to communicate a repeat of any received messages over the LCC network  38  to the first locomotive  12 . 
         [0024]    The lead locomotive is configured to act on its own upon directly receiving a message, as shown in block  60 . For example, the first LCU  22  will take the appropriate actions if the message received by the first LCU  22  has been directly received from the EOT  40 . However, if the lead locomotive does not directly receive the message, but rather receives a message from one of the trailing locomotives, then that message is used instead, as also shown in block  60 . For example, if the first LCU  22  does not directly receive the message from the EOT  40 , but instead receives the same message (e.g., having the same content) from either the second LCU  24  or the third LCU  26 , via the LCC network  38  within a set time frame, then that message will be processed by the first LCU  22 . Therefore, it is to be understood that the first LCU  22  will not process messages forwarded by the second LCU  24  or the third LCU  26  if the first LCU  22  has already received the message directly from the EOT  40 . The implementation may be designed to maintain the same number of message repeats as in a single unit operation in order to not take a larger portion than necessary of the channel use time per penalty brake application event. 
         [0025]    The lead locomotive is also configured to forward lead-locomotive-initiated penalty brake messages (or other messages) to the trailing locomotives, as shown in block  62 . Thereafter, the penalty brake messages are transmitted from the trailing locomotives to the EOT according to predefined intervals. For example, a penalty brake message is initiated in the first locomotive  12 . The first LCU  22  then transmits the penalty brake message over the LCC network  38  to the second LCU  24  and the third LCU  26 . As previously discussed, in the initial set up of the aforementioned system, the first LCU  22  assigns a “sequence number” to the second LCU  24  and the third LCU  26  to define timing slots to avoid message collisions when broadcasting repeat messages to the EOT  40 . The established timing slots are then used to send the penalty brake message from the various LCUs  22 ,  24 ,  26  in such a manner so as to not overlap and create message collisions or unnecessary message congestion. 
         [0026]    Optionally, the lead locomotive may be configured to assign its “lead” LCU communications responsibility to any of the trailing locomotives if radio failure or poor radio performance is detected in the lead locomotive. For example, the first LCU  22  may assign its role to either the second LCU  24  or the third LCU  26 . In such situations, the data display and input functions between the first LCU  22  and engineer interface are maintained in the first locomotive  12 . This is accomplished by transmitting the data originating in the first locomotive via the LCC network  38  to the newly-assigned “lead” LCU of the respective trailing locomotive, such as the second LCU  24 . 
         [0027]    It is to be understood that a typical hardware implementation of the present invention integrates two locomotive systems; namely, the EOT-LCU and the LCC. These systems may be integrated into a common physical package or as two separate packages having a data communications interface between the systems. In either case, an interface is provided to allow the LCC system to be shared for other consist communications functions. This may include, among other data, dynamic brake and tractive effort status data reporting from the trailing locomotives to the lead locomotive. 
         [0028]    The teachings of the present invention may also be applied to other locomotive data radio system applications including, but not limited to, distributed power control and electronic train management systems. With respect to a distributed power control system, a lead locomotive may communicate with one or more sets of remote locomotives using data radio. If the lead and/or trailing locomotive groups include more than one locomotive, each having data radio equipment, the same approach as previously discussed may be applied. Specifically, one locomotive within each consist group would be designated as the “lead” for data radio communications purposes. When there are other equipped locomotives within their MU group having data radios and network communications therebetween, these locomotives may share message receipts in a similar manner as outlined with respect to EOT operations. Therefore, likewise, if a radio of a “lead” fails, then the “lead” designation within that particular locomotive group may be changed. With respect to an electronic train management system, a lead locomotive generally communicates with a network of ground data radios. When there are multiple locomotives, each having data radio equipment and network communications therebetween, communications may be shared in a similar manner as outlined with respect to EOT operations. 
         [0029]    The invention has been described with reference to the desirable embodiments. Modifications and alterations will occur to others upon reading and understanding the preceding detailed description.