GB2345824A - Transferring operational data collected at remote stations to a base station - Google Patents

Abstract

Each remote operational station 401-405 associated with a vehicle of a fleet collects data such as maintenance information or data relating to the position of the vehicle determined from GPS satellite signals. A central base station 409 instructs the remote stations as to when to initiate data transfer by transmitting a GSM SMS message 421. The message specifies the time and/or dates at which data transfer is to be initiated. At the specified time, the remote station checks if the vehicle ignition is switched off and if so, initiates a data download to the base station. Data transfer takes place over a GSM data channel. Thus the base station may schedule the transfer so that all vehicles do not attempt to transfer their data simultaneously whilst the vehicles may only initiate the transfer if local conditions are satisfactory.

Description

Transferring Operational Data The present invention relates to transferring operational data collected at a plurality of remote operating stations, to a data receiving station.

The transfer of stored data from a vehicle to a data collection apparatus is described in the applicant's British patent 2 317 791 B. A system is described in which a first packet of data is transmitted from a vehicle to a data collection apparatus via a radio channel in response to a pre-determined event, such as the ignition of the vehicle being switched off. In response to this first packet being transmitted, the receiving station issues a second packet requesting data from the vehicle and, in response to receiving this second packet, the vehicle transmits a portion of the stored data to the collection apparatus. Thus, when a vehicle enters the vicinity of the collection station, it alerts the collection station as to when its ignition has been switched off ; a condition which has been identified as a"come and get me" signal. Thereafter, a request is made by the collection apparatus for a portion of the stored data.

By downloading the collected data in portions, it is possible for a number of transfers to take place such that all vehicles entering a collection region may have their data downloaded, thereby ensuring that no one vehicle monopolises the available transmission bandwidth.

The system described in the aforesaid patent facilitates the downloading of accumulated data in a highly efficient way, provided that the vehicles intermittently return to a central station or depot. However, in some environments, vehicles remain away from base for long periods of time possibly, for example, when drivers or operatives are working from home.

Furthermore, downloading techniques are also required in other environments where, for example, operational equipment remains stationary.

A system for downloading collected data from vehicles is described in United Kingdom patent application 2 288 892A. The collected data may be supplie to a modem data-collection data dump, whereafter the data may be transmitted over a communication link to reception data dumps. In accordance with this system, the vehicle is responsible for deciding when it is appropriate for a data transmission to take place. However, a problem with this approach is that many vehicles may attempt to download data simultaneously. Consequently, significant resources are required at the collection station or, altematively, it is possible that some vehicles would not be able to download, resulting in the possibility of accumulated data being lost.

A system is disclosed in International Patent publication WO 90/09645 in which recorded data is transmitted by radio to a base station as required.

The data may be transmitted when polled by the base station and the vehicles may be polled in tum either on demand or at regular intervals. The data may be transmitted by radio to the base station while the vehicle is on the road such that the vehicle does not have to be in the vicinity of the base station.

A problem with this approach is that data may be lost or corrupted if an attempt is made to transfer data while the vehicle is moving. For example, even when radio reception is relative good, the vehicle may enter a tunnel or the vehicle may be obscured by some other entity which temporarily prevents optimal data transmission. The initiative has been taken away from the vehicle in terms of deciding when it is appropriate for a data transmission to take place. Consequently, it is not possible for all of the vehicles to attempt to make a data transfer at the same time, thereby the provision of equipment at the central station may be significantly reduced. Under these operating conditions, it is the responsibility of the central station to poll the individual vehicles so that they may then in turn perform the data download. However, a problem with this approach is that the vehicles may be polled at times when it is inappropriate for the data transfer to take place, resulting in potential data loss or data corruption.

To summarise, if the initiative is taken by the vehicles in terms of deciding when to transfer data, it is possible that insufficient resources may be available at the receiving station, possibly resulting in data loss. Similarly, if the initiative is taken by the central station, in terms of polling vehicles to download data in response to a polling signal, it is possible that the polled vehicle may be in a less than ideal situation for performing the data download, again running the risk of incurring data loss.

According to a first aspect of the present invention, there is provided a method of transferring operational data collected at a plurality of remote operating stations to a data base station, wherein each operational station collects data over an operational period; said base station is configured to instruct said remote stations as to when to initiate a data transfer in response to a predefined schedule; and each operational station is configured to process instructions received from said base station, to identify a time for initiating a data transfer, and to initiate a data transfer of collected data to said base station at the instructed time.

The present invention results in the times for data transfer being controlled by the central station. However, the central station does not poll the vehicles, as shown in the previously acknowledge prior art. In preference to doing this, the receiving station instructs the remote stations as to when a data transfer may be initiated in the future. The remote stations process this instruction in order to identify a time for initiating a data transfer. In this way, the central station ensures that the vehicles transmit their collected data at different times, thereby enabling the central station to communicate with its preferred number of vehicles at any one time. Thus, the vehicles are not polled but are instructed to initiate the transfer of data in accordance with the instruction.

In a preferred embodiment, said operational stations are attached to motor vehicles and data collected over said operational period relates to the operation of the vehicle to which the operational station is attached.

Preferably, the collected data relates to geographical positions of the vehicle to which the operational station is attached. Altemabvely, or in addition thereto, the operational data relates to operational conditions of the said vehicle.

Preferably, an instruction signal identifies a specific time for a data transfer to be initiated. In addition, the instruction may instruct a remote operational station to transfer data at a particular time, at a particular day of the week and to continue transmitting at the appointed time and day until further instructions are received.

In a preferred embodiment, a checking operation is performed at the instructed time for initiating a data transfer so as to check that appropriate conditions exist for the transfer to take place. Preferably, at each vehicle, a check is made to determine whether the ignition has been switched off and a data transfer is only performed when the ignition is off. In this way, it is not possible for a data transfer to take place if the vehicle is moving.

In a preferred embodiment and as described in the present applicant's British Patent No 2 318 940 B, relative positional data is transmitted in combination with absolute positional data, so as to reduce the totality of the data that is required to be stored and transmitted. However, a problem associated with the transmission of data in this form is that the data itself is more susceptible to corruption or data loss, particularly if absolute positional data is lost. The present invention facilitates the transmission of data in this compressed form, given that data transfers may be scheduled to take place sequentially and at optimum times.

According to a second aspect of the present invention, there is provided apparatus for transmitting operational data collected at a plurality of remote operating stations to a data receiving base station, comprising means for collecting data at each operational station over an operational station; means at said base station configured to instruct said remote stations as to when to initiate a data transfer in response to a predefined schedule; and means at said operational stations configured to process instructions received from said base station, to identify a time for initiating a data transfer, and to initiate a transfer of collected data to said base station at said instructed time.

In a preferred embodiment, the base station includes means for contacting remote stations by means of GSM SMS messages and the remote stations may include means for downloading data over a GSM data channel.

According to a third aspect of the present invention, there is provided apparatus attachable to a motor vehicle and to configure to collect operational data relating to operational characteristics of said vehicle, comprising means for receiving instructional data from a base station identifying a time at which a data transfer is to be initiated; and a means for initiating a transfer of collected data to an instructing base station at said instructed time.

Preferably, the apparatus is configured to collect operational data relating to positions of a vehicle over an operational period and said apparatus may include means for receiving GPS satellite signals and means for processing signals received from said satellite in order to determine said vehicle positions.

Preferably, the apparatus includes means for receiving download instruction via a GSM SMS channel and means for downloading accumulated data back to a base station over a GSM data channel.

In a preferred embodiment, the apparatus includes means for checking that the ignition of the vehicle is switched off at the time instructed to initiate a data download and means for preventing said download occurring if the vehicle ignition is switched on.

The invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle parked outside a driver's house; Figure 2 shows a receiving station for receiving information transmitted from vehicles of the type shown in Figure 1 ; Figure 3 illustrates a map showing the location of fleet depots; Figure 4 illustrates the general operation of the data accumulation and transmission systems; Figure 5 details a data accumulation device of the type identified in Figure 4; Figure 6 details a micro controller of the type identified in Figure 5; Figure 7 details a process for the collection of data, identified in Figure 6; Figure 8 details a process for receiving download instructions, identified in Figure 6; Figure 9 details a process for testing download conditions; Figure 10 details a process for the downloading of positional data, identified in Figure 6; Figure 11 details a data collection process; Figure 12 details the structure of an instruction packet; Figure 13 illustrates the coding for quarter hour periods; Figure 14 illustrates the coding of daily pattem data; and Figure 15 details an acknowledgement packet.

A vehicle 101 is shown in Figure 1, parked outside a driver's house 102. The driver operates from home and the vehicle rarely enters a depot or similar environment where it would be possible to perform a data download operation using a locally based dedicated radio system. Information relating to the joumeys made by the vehicle are required by a central station and provision is made for this data to be collected using positional detection apparatus.

In addition to positional data, it is possible for other operational data to be transmitted from the vehicle to the central station, such as operating characteristics of the vehicle which may in tum be used by the central station in order to anticipate mechanical problems with the vehicle so that servicing and repairs may be scheduled in advance of a problem occurring.

Consequently, the vehicle transmits collected data via a mobile telephone data network, such as a GSM network, by means of an aerial 103.

In this embodiment, the collecting station is shown as a vehicle and the vehicle is primarily collecting data relating to its joumeys. However, the system is also applicable to other operational devices, which could be permanently positioned at a specific location, where data is collected relating to the operation of the device and then subsequently transmitted to a collection station. Thus, such devices would collect data over an operational period and then transfer the data at a time instructed by the central station, provided that local conditions permit. These local conditions may, for example, state that the device in all other respects must be non operational such that if the device were operating, it would not be possible for the transfer of data to take place.

An operational station, such as vehicle 101 in the preferred embodiment, collects data over an operational period and a data receiving base station is configured to instruct the vehicle as to when to initiate a data transfer in response to a pre-defined schedule. Thus, at a base station, a schedule is specified as to when it is appropriate for each vehicle in the field to perform its data transfer. A specific instruction may be to the effect that a vehicle should initiate its transfer of data at 1.00 am in the morning on a particular day. Altematively, more general instructions may be issued to the effect that the transfer should be made at a particular time on a particular day of the week, each week. Thus, for example, a vehicle could be instructed to download collected data on each Friday of the week at, say, 1.30 in the moming.

The vehicle is configured to process instructions received from the receiving station so as to identify a time for initiating a data transfer. Data transfer involves the establishment of a data transmission channel and this establishment is performed by the vehicle itself. Thus, instructions received from the collection station merely provide instructions as to when it would be appropriate for the data to be transferred and this communication does not in itself initiate or create a channel for the transfer of collected data. In the preferred embodiment, instructions specifying times when data transfers should take place are made using the small message service (SMS) of a GSM mobile telephone network. Thereafter, at the appropriate time, the actual transfer of collected data is made via a GSM data channel, having significantly greater bandwidth than an SMS channel.

When the appropriate time for initiating a data transfer is reached, the vehicle checks that it is appropriate for the data transfer to take place and the data transfer is only initiated if the local checking step is satisfied. In the embodiment, a transfer of data from vehicle 101 is only permitted if the vehicle is stationary. This condition is checked by checking the condition of the vehicle and the data transfer is only possible if the ignition to the vehicle has been switched off. Thus, although the data transfer may be scheduled for a time during which it would be expected that the vehicle should be nonoperational, a further check is made to ensure that the vehicle is actually nonoperational and the transfer of data is only possible if this non-operational condition is satisfied. Thus, for example, if a driver needs to make an emergency trip during the middle of the night, and a transfer of data has been scheduled during this period, the actual transfer of data will not take place given that the checking operation will not be satisfied. This is to ensure that the transmission of data is not interrupted and that a good communication channel is established while the communication takes place.

Vehicle 101 is configured to receive transmissions from GPS satellites in order to provide positional information. This information is recorded at specified intervals of joumeys made by the vehicle and this positional data is then collected locally by the vehicle for subsequent transmission to the receiving station. Details of the GPS system are disclosed in the applicant's British patent 2 317 791 B. Transmissions made by the vehicle, in accordance with its instructions, are received by a receiving station of the type shown in Figure 2. The receiving station also communicates by means of a GSM telephone connection. In this way, it is possible for the receiving stations to exploit the SMS messaging system for both the transmission and reception of relatively small quantities of data. The data is collected by means of a general purpose data processing system 201, preferably operating under a multi-tasking environment such as windows NT. GSM telephony communications are performed via a GSM modem 202 and an appropriate aerial 203.

The accumulation of data by data processing system 201 is performed as a background process, thereby allowing the system to be used for general purpose office activities. In this way, the information is readily available to a fleet manager as and when required. The information retained on system 201 may be made available to similar systems throughout an office by means of a local area network. A fleet manager may print results and maps etc via an appropriately interfaced printer 204 and a map 205 of the geographic area of interest may be made available for conventional marking etc.

Map 205 is detailed in Figure 3. In this example, the fleet operator has a main depot in Leeds 301, with subsidiary depots in Brighton 302, Cambridge 303 and Swindon 304. Some vehicles visit these depots regularly, thereby allowing data to be downloaded in a manner substantially as described in the present applicant's British patent specification 2 317 791 B. However, the vehicle shown in Figure 1 rarely if ever visits any of these depots, therefore provision is made for the data collected by vehicle 101 to be downloaded to station 201 by means of a public GSM telephone network.

General operation of the data accumulation and transmission system is illustrated in Figure 4. In this example, five data accumulation devices 401, 402,403,404 and 405 accumulate data for transmission to data processing system 202. As shown in Figure 4, data processing system 202 has an output display device 408, an input device 409, a central processing unit 410 and a permanent storage device 411.

Operational data is collected by each of the remote operating stations 401 to 405. After their operational period, the remote stations may download data to the receiving station. The receiving station instructs each remote station as to when to initiate a data transfer in response to a pre-defined schedule, by means of an SMS instruction 421. This SMS instruction would usually be transmitted during the operational period such that it may then be acted upon after the operational period. The end of the operational period is illustrated schematically by line 422. At the time specified by SMS instruction 421, a GSM data call 423 is made at the instructed time. In this way, it is possible for the remote stations to have some control as to when the downloading of data is performed. They initiate this downloading process and if appropriate conditions for downloading do not exist, they have the option of delaying the downloading of data until the next scheduled download period.

However, in order to ensure that the receiving station does not become overloaded, it schedules the downloading periods and transmits the scheduled data by means of an SMS instruction 421.

Data accumulation device 401 is detailed in Figure 5. The device includes a Motorola 68HC912 Micro-controller 501 running at sixteen megahertz in response to a quartz crystal oscillator 502. Micro-controller 501 includes program read-only memory for executable instructions and also communicates with a random access memory device 503 providing sixteen kilobytes of CMOS static memory. A real-time clock and memory manager circuit 504 ensures that data held within memory 503 is maintained when the remaining circuitry is switched off. In addition, circuit 504, clocked at 32768 kilohertz, also provides real-time clock information to the micro-controller 501.

In this way, it is possible for the micro-controller to maintain real-time time and date information, thereby allowing the micro-controller to interpret date and time related information and instructions, and for real-time dependent interrupt signals to be generated.

A serial interface of the micro-controller 501 communicates with a GPS module 505. The micro-controller 501 issues a request to module 505, and in response to this request, positional data is retumed from the GPS module to the micro-controller. An RS232 buffering circuit 506 provides a bidirectional communication channel between the micro-controller 501 and a GSM module 507. The micro-controller 501 is only provided with one serial port, used for communicating with the GPS module, therefore an addition serial port is configured in software using standard)/0 connections of the micro-controller. The GSM module 507 allows SMS instructions to be issued and provides for GSM data to be transmitted and received. The GSM module 507 may be a Motorola D10, providing a combined GSM phone and data module in a small fully shielded stainless steel case.

Micro-controller 501 is shown generally in Figure 6, with an indication of the interrupt driven procedures executable by the micro-controller. On initialisation, as illustrated at step 601, interrupts are enabled at step 602, whereafter the processor enters a sleep state at step 603. In this way, the processor 501 consumes minimal power when not being required to actually process events.

The processor's response to an interrupt event is illustrated at step 604. In response to an interrupt event occurring, the program counter jumps to an appropriate process identified by an interrupt vector at step 605. The process initiated at the memory location identified by this vector is performed, whereafter control retums to the interrupted process, possibly sleep state 603, at step 606.

Four interrupt events are illustrated in Figure 6. The processor receives an interrupt, as shown at step 611, in response to the vehicle ignition being switched on. After entering this condition, positional data and other related data are collected at step 612.

A ring interrupt is illustrated at step 621. In response to receiving such an interrupt, instructions from the central station, shown in Figure 2, are received by means of an SMS communication. Again, after performing this operation, control is retumed to the interrupted process.

The downloading of data, over a GSM data channel, is performed when a download flag has been set. A download flag event is identified at step 631, whereafter, at step 632, the download conditions are tested and, if the download conditions permit, the downloading of data is performed at step 633. Again, after all of the data has been downloaded, control retums to the interrupted process.

The download flag may be set in response to an immediate instruction to download data. Altematively, and in accordance with the present invention, the download flag is set in response to a real-time clock interrupt, as illustrated at step 641. Thus, in response to instructions received from the base station, a time is identified at which a download is to be performed. This alarm time is retained by the real-time clock 504, thereby allowing the microcontroller 501 to enter its wait state and an alarm interrupt is generated at the appropriate alarm time. Thus, real-time clock 504 generates a real-time interrupt shown at step 641 which in tum results in the download flag being set at step 642. In response to this, a further interrupt is generated at step 631 as previously described.

The ring interrupt initiated at step 621 and the download interrupt initiated at step 631 should not themselves be interrupted by other interrupt processes. Consequently, these interrupt processes are given higher priority than the other interrupt processes that are not so time critical.

Process 612 for the collection of data is detailed in Figure 7. After detecting the ignition on condition at step 611, process 612 effectively enters a ten second wait state at step 701. Thereafter, data is collected, by means of enquiries to the GPS module 505, at step 702. At step 703 a question is asked as to whether the ignition is still on and, if answered in the affirmative, control is returned to step 702. Eventually, the ignition will be switched off, resulting in the question asked at step 703 being answered in the negative, whereafter a retum from interrupt instruction is generated at step 704.

Process 622 for receiving download instructions is detailed in Figure 8.

An instruction is transmitted from the base station to a remote station by means of an SMS message, a facility available when communication is established between two GSM telephones or GSM modems. The base station initiates a communication to a particular remote station, with appropriate telephone protocols being overseen by the GSM module 507.

This then results in a packet of information being supplie to the microcontroller 501 via the buffering circuit 506.

Process 622 is interested in receiving packets of a particular type via the SMS protocol which, for the purposes of this embodiment, have been identified as"AEM+4"packet types. Consequently, a question is asked at step 801 as to whether an AEM+4 packet type has been received and when this question is answered in the negative, control is directed to step 807 to generate a retum from interrupt command.

If the question asked at step 801 is answered in the affirmative, the download instructions are analysed at step 802 and, as a result of this analysis, data registers, memory locations and real-time clock 504 are updated where appropriate.

If, in response to the analysis performed at step 802, it is determined that the"NOW"bit of the message has been set, the download flag is set at 803, subsequently resulting in a download flag event interrupt being generated at step 631. At step 804, the number of the transmitting base station is stored, to facilitate subsequent data communications at the instructed time.

At step 805 current position data is retrieved from GPS module 505 whereafter at step 806 an SMS message, including the current position, is transmitted back to the base station as confirmation to the effect that the original instruction had been received. Thereafter, control is directed to step 807.

Step 662 for the testing of download conditions is detailed in Figure 9.

In this example, the remote stations are prevented from performing a data download if the ignition to the vehicle is switched on, suggesting that the vehicle is moving or is about to move. In such circumstances, there is a risk that data transmission could be lost, resulting in the loss of positional data.

However, in alternative embodiments, other tests could be performed appropriate to the local conditions. Thus, the system could be deployed in vending machines and a test could be performed to determine whether the vending machine is non-operational. Thus, under such circumstances, data, relating to the day's takings of the vending machine for example, may only be transmitted back to a base station when the vending machine is not actually in the process of performing a vending operation. The importance of this process is to ensure that the data is reliably transmitted with minimal risk of data loss. Furthermore, this also ensures that the data download operation does not interfere with the normal data collection operation of the environment itself.

At step 901 a question is asked as to whether the vehicle ignition is switched off and if answered in the affirmative, control is then directed to step 633. If, however, the question asked at step 911 is answered in the negative, a retum from interrupt instruction is generated at step 902. Thus, the interrupt procedures initiated at step 631 are terminated and control is retumed back to the interrupted process.

In addition to ensuring that environmental conditions do not cause positional data to be lost during the download, the procedure of performing the download when the system is non-operational also ensure that the downloading transmission, over the GSM data channel, does not result in the corruption of positional data received from the GSM satellite. Thus, referring to Figure 5, non-operational periods exist during which the GSM module is active, possibly resulting in positional data being downloaded over a GSM data channel. Similarly, operational periods exist during which the GPS module is on-line, during which satellite signals are received by its antenna.

However, the downloading of data should be scheduled such that it is not possible for these modules to be simultaneously in use, thereby ensuring that there is no mutual interference.

Process 633 for the downloading of positional data is detailed in Figure 10. At step 1001 the base station is dialled using the ATD (AT Dial) command with the number stored as a result of an instruction being received.

At step 1102 a question is asked as to whether the call has been answered and if answered in the negative, a wait state of two minutes is entered at step 1003, whereafter the process initiated at step 1001 is repeated.

When the call has been answered, resulting in the question asked at step 1002 being answered in the affirmative, the download flag is reset at step 1004 and a"come and get me"packet is transmitted at step 1005. This alerts the base station to the effect that a downloading procedure is to be commenced and ensures that both the transmitting remote station and the receiving base station are prepared for this transfer of data.

At step 1006 the process enters a wait state, this line waiting for a response from the base station and at step 1007 a question is asked as to whether a request for packets has been received. If this question is answered in the negative, to the effect that a request has not been received, control is directed to step 1010.

After receiving a request, resulting in the question asked at step 1007 being answered in the affirmative, the next sixty-four stored records are transmitted over the GSM data channel at step 1009.

On the second iteration of this loop, from steps 1006 to 1009, the download flag is set at step 1008 such that, should the communication fail for whatever reason, the process is made aware that a download was in process and efforts will be made to re-establish the connection.

The data transmitted to the base station includes an indication as to how much data is present therefore when all of the data has been received by the base station it will cease to issue requests for more data.

Consequently, the question asked at step 1007 will be answered in the negative and control will be directed to step 1010.

At step 1010 a"clear records"packet is detected resulting in all records within the memory being cleared and the download flag being reset.

Thereafter, at step 1012 the communication is terminated by the generation of a data string representing"+++"followed by the ATH (AT Hang) command.

The +++ string is identified by the GSM modem as an instruction to cease transmitting data on the basis that the next instruction will be a local off-line instruction for it, rather than a data string to be transmitted. Thereafter, the procedure retums from interrupt at step 1012.

Process 612 for the collection of data is detailed in Figure 11. At step 1101 a question is asked as to whether this is the start of the joumey, which would be answered in the affirmative on the first iteration. Consequently, the date and the start time are stored at step 1102. At step 1103 the absolute latitude is stored and at step 1104 the absolute longitude is stored.

The processor enters a loop including wait state 1106 until it is time, usually after a period of 10 minutes for the next data entry to be recorded.

Thus, after this period of time, the question asked at step 1105, as to whether it is time to record data, will be answered in the affirmative, resulting in control being directed to step 1107.

At step 1107 a question is asked as to whether the ignition is on and if answered in the affirmative relative data is recorded at step 1108. Thereafter, control is retumed to step 1105. Eventually, the ignition will be switched off, resulting in the question asked at step 1107 being answered in the negative.

On detecting this condition, control is directed to step 1109, resulting in the stop time being recorded, whereafter control is returned to step 603.

The structure of an AEM+4 packet, of the type detected at step 808, is detailed in Figure 12. A packet 1201 contains a total of twenty-two bytes, with each byte conveying information of a particular type dependent upon its position within the overall packet. A first byte identifies the overall packet type. In this example, the type may identify the packet as an instruction or as an acknowledgement.

The second byte identifies a unique reference number and this allows duplicates to be identified and discarded. The third packet identifies the calling phone number length followed by a fourth packet identifying an international calling code. This is followed by bytes five to ten which have been allocated for the provision of a phone number although for a particular phone number not all of these bytes may be required and the total length of the number is identified by the phone number length byte, byte three. Byte eleven provides information relating to a protocol identifier followed by a byte (twelve) to identify the format of the user data, such as eight-bit format or seven-bit format for example.

Byte thirteen identifies a validity period, typically of twenty minutes.

This is the period over which the SMS system will continue to transmit the SMS message and will then give up after this period if transmission has not been successful. The GSM system attempts to establish a telephone call and the system is made aware of the fact that a receiving telephone is either active, in use or not available. Thus, if it is not possible to make the transmission due, for example, because the receiving equipment is switched off, the GSM system will wait until a flag has been set identifying a condition to the effect that the equipment is available to receive the information, If this flag setting operation does not occur within the validity period, the system will cease attempting to make the communication.

The fourteenth byte identifies the length of the following user-data which, in this embodiment, is set to a byte length of eight bytes. Bytes fifteen, sixteen, seventeen and eighteen transmit the characters AEM4, with the AEM characters being represented in ASCII and the digit four being represented as binary 4. This is then followed by four bytes of the actual download instructions.

The four byte download instructions have been expanded to bit level in Figure 12, thereby providing a total of thirty-two bits for conveying the download instructions. The first sixteen bits represent a transmission day, with seven bits being allocated to represent the year, four bits being allocated to represent the month and the remaining five bits being allocated to represent the day. This is then followed by five bits representing the hour, with the next two bits representing quarters of the hour. The twenty-fourth bit is a flag which is set to indicate that the data is to be transmitted in the future in accordance with the instruction and in accordance with the present invention. The twenty-fifth bit is set if a download of information is required now, ie as an immediate response to the SMS message being received. The remaining seven bits are used to represent repeat days. Thus, these bits are effectively used as flags indicating that a repeat is to occur on Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and/or Sunday.

The nature of the packet allows different download operations to be instructed. If the"now"flag is set, the download occurs immediately, subject to local conditions permitting. If the"then"flag is set, instructions are interpreted for a download to occur in the future. It is possible for both the "now"flag and the"then"flag to be set, such that a download occurs immediately and a subsequent download instruction is recorded.

If the year, month and day information relate to a day in the future, a download instruction is recorded to the effect that an instruction must take place on that day. This may then be followed by repeat day information at the specified hour. Altematively, the year, month and day information may relate to a day that has passed, in which case this information is ignored and repeat instruction data is considered at the specified hour and quarter hour.

Coding for the quarter hour periods is illustrated in Figure 13. The value of 00 results in the download occurring exactly on the hour, with a value of 01 representing fifteen minutes past the hour, a value of 10 representing thirty minutes past the hour and a value of 11 representing fortyfive minutes past the hour.

A single repeat day may be specified in the repeat data or altematively multiple repeat days may be specified, as illustrated in Figure 14. It can be seen from Figure 14 that a repeat day sequence of 0000010 represents a download to occur every Saturday. Similarly, 0101000 represents download every Tuesday and Thursday, with 1111100 representing download Monday to Friday and a full run of 1's representing download every day.

A confirmation type packet, the type transmitted at step 806, is detailed in Figure 15. The packet identifies packet type followed by a phone number length, international code and vehicle phone number. This is then followed by a byte representing the protocol identifier and user data format.

Bytes are then allocated representing the time and date on which the message was sent, followed by a byte representing the length of user data.

The user data includes a total of 15 bytes, representing the date, time at which the vehicle started and stopped, the vehicle longitude, the vehicle latitude, speed, mileage and a representation of the download flag.

It can be appreciated that the invention provides for the advantage of base station driven polling to be combined with the advantage of vehicle initiated transmission. The base station has a schedule defining when data transfers are to take place. Instructions are then transmitted over SMS to each individual operational station providing instructions as to when, in the future, a data transmission is to be initiated. The initiation of the data transfer is then under the control of the operational stations themselves, allowing the data transfer to take place only if local conditions permit.

Claims (24)

Claims

1. A method of transferring operational data collected at a plurality of remote operating stations to a data base station, wherein each operational station collects data over an operational period; said base station is configured to instruct remote said stations as to when to initiate a data transfer in response to a predefined schedule; and each operational station is configured to process instructions received from said base station, to identify a time for initiating a data transfer, and to initiate a transfer of collected data to said base station at said instructed time.

2. A method according to claim 1, wherein said operational stations are attached to motor vehicles and data collected over said operational period relates to the operation of the vehicle to which the operational station is attached.

3. A method according to claim 1, wherein said collected data relates to geographical positions of the vehicle to which the operational station is attached.

4. A method according to claim 2 or claim 3, wherein said data relates to operational conditions of the said vehicle.

5. A method according to any of claims 1 to 4, wherein an instruction signal identifies a specific time for a data transfer to be initiated.

6. A method according to claim 5, wherein said instruction instructs a remote operational station to transfer data at a particular time, at a particular day of the week and to continue transmitting at the appointed time and day until further instructions are received.

7. A method according to any of claims 1 to 6, wherein said base station contacts remote stations by means of GSM SMS messages.

8. A method according to any of claims 1 to 7, wherein remote stations download data by means of a GSM data channel.

9. A method according to claim 1, wherein, at the instructed time, a check is made to determine whether appropriate conditions exist for the data transfer to take place.

10. A method according to claim 10, wherein said checking operation involves checking that the ignition of a vehicle is switched off.

11. Apparatus for transmitting operational data collected at a plurality of remote operating stations to a data receiving base station, comprising means for collecting data at each operational station over an operational period; means at said base station configured to instruct said remote stations as to when to initiate a data transfer in response to a predefined schedule ; and means at said operational stations configured to process instructions received from said base station, to identify a time for initiating a data transfer, and to initiate a transfer of collected data to said base station at said instructed time.

12. Apparatus according to claim 11, wherein said base station includes means for contacting remote stations by means of GSM SMS messages.

13. Apparatus according to claim 11 or claim 12, wherein said remote stations include means for downloading data over a GSM data channel.

14. Apparatus according to any of claims 11 to 13, wherein said remote stations include means for checking to determine whether an appropriate condition exists for a data transfer to take place.

15. Apparatus according to claim 14, wherein said means for checking an appropriate condition is configured to check that the ignition of a vehicle has been switched off.

16. Apparatus attachable to a motor vehicle and configured to collect operational data relating to operational characteristics of said vehicle, comprising means for receiving instructional data from a base station identifying a time at which a data transfer is to be initiated; and means for initiating a transfer of collected data to an instructing base station at said instructed time.

17. Apparatus according to claim 16, configured to collect operational data relating to positions of a vehicle over an operational period.

18. Apparatus according to claim 17, including means for receiving GPS satellite signals and means for processing signals received from said satellites in order to determine vehicle positions.

19. Apparatus according to any of claims 16 to 18, including means for receiving download instructions via a GSM SMS channel.

20. Apparatus according to any of claims 16 to 19 including means for downloading accumulated positional data over a GSM data channel.

21. Apparatus according to any of daims 16 to 20, including means configured to check that the ignition of the vehicle is switched off at the time instructed to initiate a data download and means for preventing said download occurring if the vehicle ignition is switched on.

22. A method of transferring operational data collected at a plurality of remote operating stations substantially as herein described with reference to the accompanying drawings.

23. Apparatus for transmitting operational data collected at a plurality of remote operating stations to a data receiving base station substantially as herein described with reference to the accompanying drawings.

24. Apparatus attachable to a motor vehicle and configured to collect operational data relating to operational characteristics of the vehicle substantially as herein described with reference to the accompanying drawings.