Transferring accumulated data from vehicles

Abstract

Accumulated data is transferred from a plurality of vehicles to a data processing station by transmitting a first packet type request from each vehicle via an open radio channel in response to a predetermined operation. This operation may include the vehicle's ignition being turned off. The first packet type is detected at a receiving station if a transmitting vehicle is within the vicinity of the receiving station. The receiving station transmits an instruction for data in the form of a second packet type upon detecting a first packet type. Thereafter, a portion of the accumulated data is transmitted from a detected vehicle in response to instructions generated by the receiving station.

1 . A method of transferring accumulated data from a plurality of vehicles to a data processing station, characterised by steps of 
 transmitting a first packet type request ( 431 ) from each vehicle ( 401  to  405 ) via an open radio channel in response to a predetermined operation;    detecting said first packet type at a data processing station ( 202 ) if a transmitting vehicle is within the vicinity of said receiving station;    transmitting an instruction for data in the form of a second packet type ( 432 ) from said receiving station ( 202 ) upon detecting said first packet type; and    transmitting a portion ( 433 ) of said accumulated data from a detected vehicle in response to said instruction.    
     
     
         2 . A method according to  claim 1 , wherein said accumulated data (FIG. 7) represents vehicle positions.  
     
     
         3 . A method according to  claim 2 , wherein said positional data is derived by receiving radio signals from satellites.  
     
     
         4 . A method according to any of  claims 1  to  3 , wherein said data processing station includes a data collection point ( 406 ) for receiving and transmitting radio signals and a data processing system ( 202 ) for storing received data.  
     
     
         5 . A method according to any of  claims 1  to  4 , wherein said predetermined operation consists of the vehicle ignition being turned off.  
     
     
         6 . A method according to  claim 5 , wherein the accumulation device records positional information when the ignition is turned on.  
     
     
         7 . A method according to any of  claims 1  to  6 , wherein said first packet type is transmitted after a relatively random period so as to minimise the risk of two vehicles transmitting at the same time.  
     
     
         8 . A method according to any of  claim 1  to  7 , wherein accumulated data may only be transmitted in response to an instruction from a receiving station.  
     
     
         9 . A method according to any of  claims 1  to  8 , wherein the size of a transmitted portion ( 433 ) is restricted so that a packet containing said data portion may not exceed a predetermined size.  
     
     
         10 . A method according to any of  claims 1  to  9 , wherein each radio packet controller is arranged to examine its receiver to determine whether any other transmissions are occurring, such that transmissions are only made when the transmission frequency is not being used by another device.  
     
     
         11 . A method according to any of  claims 1  to  10 , wherein particular accumulation devices mounted to particular vehicles are identified by a unique address.  
     
     
         12 . A method according to any of  claims 1  to  11 , wherein an instruction ( 436 ) to clear memory is transmitted by said data processing station after the final portion of accumulated data has been received by said data processing station.  
     
     
         13 . A method according to any of  claims 1  to  12 , wherein priority is given to particular data accumulation devices or particular sets of accumulation devices.  
     
     
         14 . A method according to  claim 13 , wherein priority is given to accumulation devices having relatively full memories.  
     
     
         15 . A method according to any of  claims 1  to  14 , wherein positional data is not recorded at specified times.  
     
     
         16 . Apparatus for accumulating data at a vehicle ( 401  to  405 ) and for transferring said accumulated data to a data processing station, characterised by 
 means ( 401 ) for transmitting a first packet type ( 431 ) over an open radio channel to request transmission of accumulated data;  
 means for receiving an instruction in the form of a second packet type ( 432 ) from a receiving station ( 202 ) if the transmitter is within the vicinity of said receiving station; and  
 means ( 401 ) for transmitting a portion ( 433 ) of said accumulated data in response to said received instruction.  
 
     
     
         17 . Apparatus according to  claim 16 , including means for identifying the position of the vehicle and means for accumulating data representing said positions.  
     
     
         18 . Apparatus according to  claim 17 , wherein said means for generating positional data includes means for receiving radio signals from satellites.  
     
     
         19 . Apparatus according to  claim 16 , including means for initiating a transmission in response to the ignition of the vehicle being turned off.  
     
     
         20 . Apparatus according to  claim 16 , including means for accumulating position information in response to the vehicle ignition being turned on.  
     
     
         21 . Apparatus according to  claim 16 , including means for transmitting said first packet type after a relatively random period so as to minimise the risk to vehicles transmitting data at the same time.  
     
     
         22 . Apparatus according to  claim 16 , including means for detecting whether a radio channel is available prior to transmitting a packet of data.  
     
     
         23 . Apparatus according to  claim 16 , including means for recording a unique address for the device.  
     
     
         24 . Apparatus according to  claim 16 , including means for clearing data accumulation memory in response to receiving an appropriate instruction from a processing station.  
     
     
         25 . A receiving station ( 202 ) for receiving accumulated data from a plurality of vehicles, characterised by 
 means for receiving a first packet type request ( 431 ) from each vehicle via an open radio channel;    transmitting means ( 406 ) for transmitting an instruction for data in the form of a second packet type ( 432 ) upon detecting said first packet, wherein    said receiving means is arranged to receive portions ( 433 ) of said accumulated data from detected vehicles in response to said instructions.    
     
     
         26 . Apparatus according to  claim 25 , wherein said received data represents vehicle positions.  
     
     
         27 . Apparatus according to  claim 25 , including a data collection point ( 406 ) for receiving and transmitting radio signals and a data processing system for storing said received data.  
     
     
         28 . Apparatus according to  claim 25 , including means for detecting whether a radio channel is available prior to transmitting instructions.  
     
     
         29 . Apparatus according to  claim 25 , including means for identifying unique addresses within received packets.  
     
     
         30 . Apparatus according to  claim 25 , including means for transmitting a packet instructing accumulation devices to clear storage memory.  
     
     
         31 . Apparatus according to  claim 25 , including means for prioritising the accumulation of data from a plurality of accumulation devices.  
     
     
         32 . Apparatus according to claim  31 , wherein said prioritising means includes means for giving priority to accumulation devices having relatively full memories.