Intra-train radio communication system

A method for communicating and verifying commands in an intra-train radio communication system comprising the steps of:

• transmitting a command message from a lead unit installed in a first locomotive;
• receiving the command message in a first remote unit installed in a second locomotive;
• generating a first status message in the first remote unit in accordance with a content of the command message;
• transmitting a first reply message from the first remote unit during a first predetermined time period, the reply message containing the first status message and a message representing said command message;
• receiving said first reply message by a second remote unit installed in a third locomotive;
• generating a second status message in the second remote unit in accordance with said message representing said command message;
• transmitting a second reply message from the second remote unit during a second predetermined time period, said second reply message containing the second status message;
• and
• monitoring by the lead unit the first and second reply messages in the first and second predetermined time periods, respectively.

An intra-train radio communication system comprising:

• a plurality of communication modules, each communication module mounted in a respective one of a plurality of locomotives in a train consist and including a radio transmitter and receiver, a control module connected to and controlling the radio transmitter and receiver, a user interface connected to the control module for inputting data and commands by a user and outputting information to the user, and a hardware interface connected to the control module for receiving inputs from and outputting commands to a locomotive in which the communication module is mounted;
• one of said communications modules being designated as a lead unit and others of the plurality of communications modules being designated as remote units, the lead unit and the remote units being linked by a Carrier Sense Multiple Access (CSMA) radio channel, the lead unit and the remote units storing a unique identifier for the lead unit, the lead unit further storing unique identifiers for each of the remote units, each of the remote units storing the unique identifier for the respective remote unit, and the lead and remote units storing an index indicating a position of the unit in the train consist;
• radio communication between the lead unit and the remote units being effected by sending a message having a source field containing the unique identifier for the particular sending unit, a destination field in the form of a unique identifier for a particular one of the receiving units or a broadcast identifier common to all remote units, an index field indicating the position of the unit in the train consist, a command field specifying a command to be executed by one or more of the remote units, and a status field specifying a status of an originating remote unit;
• when a remote unit receives a message from the lead unit, the remote unit compares contents of the source field against the stored unique identifier for the lead unit and compares contents of the destination field against the broadcast field and the unique identifier for the remote unit and, if the source field and the stored unique identifier for the lead unit match and the destination field matches either the broadcast identifier or the unique identifier for the remote unit, the receiving remote unit executes the command in the command field and transmits a status message during a predetermined time slot assigned to the lead unit in a Time Division Multiple Access (TDMA) scheme, the predetermined time slot being measured as a function of a difference in the remote unit's stored index and the index field of the received message, the status message including a rebroadcast of the transmission from the lead unit and any requested information in the status field;
• but if only the source field and the stored unique identifier for the lead unit match, the remote unit transmits the status message to the lead unit without executing the command in the command field;
• and
• the lead unit monitors predetermined time slots for each of the remote units and detects a communication failure by a remote unit failing to reply with a status message during its predetermined time slot.

A method of intra-train radio communication comprising the steps of:

• installing a plurality of communication modules in respective ones of a plurality of locomotives in a train consist, each communication module including a radio transmitter and receiver, a control module connected to and controlling the radio transmitter and receiver, a user interface connected to the control module for inputting data and commands by a user and outputting information to the user, and a hardware interface connected to the control module for receiving inputs from and outputting commands to a locomotive in which the communication module is mounted;
• designating one of said communications modules as a lead unit and others of the plurality of communications modules as remote units;
• linking the lead unit and the remote units by a Carrier Sense Multiple Access (CSMA) radio channel;
• storing in the lead unit and the remote units a unique identifier for the lead unit;
• storing in the lead unit unique identifiers for each of the remote units;
• storing in each of the remote units the unique identifier for the respective remote unit;
• storing in the lead and remote units an index indicating a position of the unit in the train consist;
• sending a message between the lead unit and the remote units, the message having a source field containing the unique identifier for the particular sending unit, a destination field in the form of a unique identifier for a particular one of the receiving units or a broadcast identifier common to all remote units, an index field indicating the position of the unit in the train consist, a command field specifying a command to be executed by one or more of the remote units, and a status field specifying a status of an originating remote unit;
• receiving at a remote unit a message from the lead unit;
• comparing by the remote unit contents of the source field in a received message from the lead unit against the stored unique identifier for the lead unit and comparing contents of the destination field against the broadcast field and the unique identifier for the remote unit;
• if the source field and the stored unique identifier for the lead unit match and the destination field matches either the broadcast identifier or the unique identifier for the remote unit, executing by the receiving remote unit the command in the command field;
• transmitting by the remote unit a status message to the lead unit, the status message including a rebroadcast of the transmission from the lead unit and an indication as to whether the command has been carded out and provides the lead unit with any requested information in the status field;
• the status message being transmitted in the predetermined time slot assigned to the lead unit in a Time Division Multiple Access (TDMA) scheme, the predetermined time slot being measured as a function of a difference in the remote unit's stored index and the index field of the received message;
• but if only the source field and the stored unique identifier for the lead unit match, then transmitting by the remote unit the status message during the predetermined time slot without executing the command in the command field;
• and
• monitoring by the lead unit predetermined time slots for each of the remote units and detecting a communication failure by a remote unit failing to reply with a status message during its predetermined time slot.