CA1241113A - Data capture system - Google Patents

Abstract

ABSTRACT

DATA CAPTURE SYSTEM
The system involves the fitting of Electronic Number Plates (ENP's) to all road vehicles with roadside interrogators (outstations OS) and central control equipment to collect and validate vehicle identity data before passing it on to an accounts processing system AP.
The system is organised so that there are a number of vehicle data processing devices (Data Validators DV) which receive data from the outstation units (OS) interrogated by a communications controller (CCL). Each Data Validator (DV) is allocated a discrete subset of all vehicles in the system to enable vehicle location checking to be maintained as the vehicles move through the system. Any apparent error in vehicle data is passed on to a supervisory processor which checks if the error can be explained. This provides a powerful vehicle location consistancy check and fraud identification system allowing speed detection of fraud, stolen cars or electronic number plates.

Description

DATA CAPTURE SYSTEM
This invention relates to a data capture system for the automakic charging of tolls to vehicular users of roads.
According to the present invention there is provided a data capture system for the automatic charging of tolls to vehicular users of roads, the capture system comprising, a plurality of vehicle identity data transmittinq means each being individually attachable to vehicles, a plurality of roadside vehicle identity data interrogating means linked by a communications net~ork with a central control which includes a plurality of communications control processors, and a plurality of vehicle identity data validating processors which communicate by means of a common inter-processor bus, wherein each data validating processor is allocated a discrete subset of all vehicles handled by the system and wherein upon transmitted vehicle identity data being detected by any one roadside vehicle identity data i.nterrogating means, the vehicle identity data is transmitted through the communications network to a communications control processor and then by way of the common inter-processor bus to the particular data validating processor allocated to the subset of vehicles within which, the detected vehicle identity data is located, whereupon, the detected veilicle identity data is validated for use in enabling the preparation of toll invoices for despatch to the particular vehicle user ~i coneerned.
The invention will be better understood from the following description of an exemplary embodiment whieh should be read in conjunction with the accompanying drawings, in which:
Figure 1 shows a plan-view of the apparatus whieh comprises an electronie number plate;
Figure 2 shows a side-view of the apparatus shown in Figure 1, Figure 3 shows a bloek schematic of the data capture system in accordance with the invention;
Figure 4 shows a flow diagram for the data validation proeessing;
Figure 5 shows a flow diagram for the anomaly processing/fraud identification for the supervisory processor.
The data capture system comprises electronic number plates (ENPs) fitted to road vehieles, roadside interrogators, data transmission equipment and central offiee equipment to eolleet and validate vehicle identity data before passing it on to an aeeounts proeessing system.
_L _ RONIC Nt1MBER PLATE (ENP) Referring now to the drawings; each vehicle in the system is fitted with vehicle identity data transmitting means or electronic n~mber plate (ENP).
The ENP 1, (as shown in Figure 1 and Eigure 2), is a small sealed module approximately 200mm long x 75mm wide and 40mm deep. It is located by means of securing points

2 and 3 beneath vehicle body 4. It is easy to fit, but once fitted is dif~icult to remove.
Each ENP apparatus has a unique identifyin~ serial number which is converted into code and stored in the ENP
apparatus during manufacture. All ENP apparatus codes are independent of any vehicle mechanical registration number, making it difficult to copy and defraud.
At the fitting station where the vehicle is equipped, the vehicle registration number is entered into the system by an operator via a keypad, whilst the serial number is read automatically into the system by an interrogator.
This serial number is not displayed to the operator, for security rea~sons. The ENP apparatus is eguipped with two aerials 5 and 6 which provide electromagnetic coupling with inductive road loops (cables buried in the road). One aerial receives sufficient energy to power up the ENP apparatus when it is in the immediate vicinity of a power loop PL. This aerial also provides a clock input for the ENP circuits which generate the synchronous data to be transmitted via the other aerial back to a receive loop RXL.
The ENP apparatus receives its po~er and clock at 147kHz and transmits the data on a 73.5kHz carrier. The data rate is 9.1875kBaud, i.e. one sixteenth of the powering frequency.
The ENP apparatus contains three integrated circuits (IC's). One, a fuse-link PROM, is programmed with the ~X~ 3 serial number code during manufacture. Another, a CMOS
custom IC performs all logic functions, and a special bi-polar IC, measures si.gnal thresholds and performs the linear functions. These IC's, to~ether with other components, are mounted on a printed circuit board 7.
The ENP apparatus is capable of transmitting the serial code (in phase modulated form), a security or check code for providing an extra protection against fraud, and (optionally) variahle data set-up by the driver of the vehicle on a varia~le data unit within the vehicle Various types of variable data unit's can be used.
Some o~ the data field being varied automatically ~y peripheral equipment connected via the unit. This may include such items as emergency vehicle status and priority code, bus identification, depot, fleet and route number. The remainder of the data field being varied by switches on the unit.
_UTSTATIONS
Along the roadside RS are located vehicle identity interrogating means or outstations OS which comprise an interrogator, which is connecte~l to the inductive road loops (power PL and receive RXJ, a processor, a trans-mission unit and a num~er of inteefaces to local equipment, such as a tol.l display T[) wllcre charges are indicated, a closed ci.rcuit televisi.on control CCTVC, a mai.ntenance handset or terminal TM through which police and maintenance services gain access to information, and a priority controller PC for handling control signals relating to vehicles requiring priority.
CCTV SYSTEM
The CCTV system includes cameras C at certain road-side interro~ation points (outstation OS) which store pictures of vehicles in a category termed suspect, for onward transmission to the central control CC for analysis. A suspect vehicle could be one Eor which no identity data is receive~, one where the security code or location is found to be inconsistent, or one wanted by the police, for example a stolen vehicle. A list of suspect vehicles (the 'Wanted List') is held by the supervisory processor SP at the central control CC.
SYSTEM IN GENERAL
It is arranged for the interrogator to demodulate signals received from each receive loop RX and pass the identity data to the processor where the code is verified.
Vehicle identity data are subsequently transmitted from the outstations OS by the transmission unit, central control CC by way of a communications network CN in the form of cable network. Each communications controller CCL
ha~ control of a part of tl~e complete cable network, with a number oE outsta~ion~ (e.q. ten) connected (via the network) to each of its communications channels. The central control CC comprises a number of communications controllers CCL, a number o~ processors (accounts processor AP, Supervisory processor SP, fleet location processor FLP, traffic statistics processor TSP, data validation processor or data validator DV, and a spare ~2~ 3 processor SPE), disc and tape storage, and operator communication facilities OC which include visual clisplay units (VDTJ's) and a hard copy terminal or printer.
The communications controllers CC, handle data transmission between the outstations and a high speed bus IPB to which all the central eontrol processors are connected. The IPB is a local area network link arrangement termed an ETHERNET bus whieh operates lO Mbits over a single eoaxial cable. Proeessors tap into the cable at intervals allowing up to 100 stations (nodes) on a 500m eable with up to 1024 stations in any network.
Concerning the various processors mentioned above, the data validation processors or data validators DV check the seeurity code ( if used) and loeation (outstation) of eaeh ENP against the last known interrogation data, an accounts processor AP, prepares road eharge invoiees and despatehes these periodieally to the vehiele owners and a supervisory proeessor SP oversees the operation of the data validators DV, co-ordinates fault detection and 2~ recovery, including checking if apparent errors in vehicle data can be explained by faults known to the system ('Anomaly Processing'), and handles operator comml~nications.
Data received ~rom the outstation units OS are interrogated ~y the associated communications controller CC ancl passed to the appropriate data validator DV via the high speed b~s (local area communications network IPR).

Each data validator DV is allocated a discrete s~bset of all vehicles in the system, to enable vehicle location checking to be maintained as the vehicles move through the area, and are detected by the different outstation units OS and, hence, different communications controllers CC.
Any apparent error in vehicle data is passed on to the supervisory processor SP, which checks if the error can be explained by known faults in the system, such as a faulty upstream interrogator. At the same time, if the vehicle was detected at a manned or CCTV outstation, data is sent to that outstation Eor display on the local terminal or inclusion with display at the central control.
Valid vehicle data is output for use by the accounts processor AP.
Data that fails the validity check ànd anomaly analysis causes that ENP to be marked as 'suspect' in the computer records. It is added to the IWanted List' in the supervisory processor SP and marked for special attention in the data validator DV responsible for that ENP.
COMrlUNICATION CONTROLLERS
Referring to the Communications Controllers CCL these poll each outstation in turn to retrieve the vehicle inEormation. Any control information being sent from the central control CC to an outstation OS is included in the ~ppropriate poll request frame. The protocol adopted perlrits messages to be sent from the communication controllers CCL to all units on a line. The protocol ; used is the internationally agreed standard for High Level Data Link Control Procedures (HDL,C).

The main function of the communication controller CCL is to buffer the individual vehicle information for onward transmission to the data validators DV. It determines frorn each vehicle's ENP code which data validator DV is 5 the required destination. (It should be noted that there are several data validators DV each processing a subset of all vehicles in the systeml. The communication controller CCL sets up output buffers accordingly and then sends the data to the destination~s).
TRANSFER OF DATA (OUTSTATION TO CENTRAL OFFICE) Priority is given to any outstation unit which is connected to CCTV equipment or which has a terminal connected to it; for these sites, information from the outstation may elicit a response from the central control.
Usually the response will relate directly to a vehicle passing the site, so it is essential to get the response to the outstation quickly ~before the CCTV equipment overwrites a stored picture frame with another picture, or before the vehicle has moved too far away from a manual site to permit police intervention). Consequently these sites are marked as 'high priority' and will be polled by a communication controller CCL at about twice per second, interrupting the sequential polling of each of the other (low priority) outstations.
~s an outstation only transmits information to the central control when asked to do so by a communication controller CCL, different types of information can be combined into one data packet, depending upon what is requested by a communication controller the current status of the equipment at the outstation at the time of polling. These types include:-a) Vehicle ENP data;
b) Site and lane identification, per set of ENP data;
c) Fault indications;
d) Toll charge confirmation;
e) Whether a terminal is connected to the outstation's handset port;
f) Messages and/or commands from the terminal; and g) The results of a 'self check' by the outstation processor.
Note that these types are for standard outstations operating manually. In addition to these, outstation lS initialisation involves several 'supervisory' data packets to set up the link to a communicaions controller CCL and acknowledge completion of the initialisation process.
As a communication controller CCL receives outstation data packets, it sends vehicle ENP information to the data validators DV and all other information to the supervisory processor SP. For each set of ENP information, the vehicle's ENP serial number is used to identify which data vallc3ator DV holds its currer1t location (and security code, if any) and different data packets are set up to send to each data validator DV. High priori-ty site data is separated from low priority site data so tl1at the data validator DV is synchronised to the end oE polling of the high priority outstations.

--1,1--TRA~SFER OF DATA (CENTRAL O~FICE TO OUTSTATION) The normal data transmitted from a communication controller CCL to an outstation is a poll for vehicle ENP
data. The following items may be incorporated within the 'poll request' packet:
a) Toll charge updates;
b) Equipment fault clearance;
c) Instructions to outstation units to perfor~ self check;
d) Requests for self check test results;
e) Replies to messages/commands input from the engineer's terminal; and f) Confirmation of vehicle commissioning.
The following items are interleaved with the poll request packets:
a) Outstation initialisation and down line loading information; and b) 'Wanted Vehiclel requests.
HDLC PROTOCOL
As each outstation OS com~unicates with a single communications controller CC, the operating mode ~or the links is that of primary-secondary polling. The communication controller CCL acts as the primary (master) station and the outstations on each link as the secondary (slave) stations.
Each communication controller CCL outstation 'link' is set-up for frame transmission and messages are passed 2~ 3 in the form of a header (made up of the r~quired outstation address and control information), an information field and a frame check sequence. As the message is received, the frame check sequence is re-computed and checked against the frame check sequence at the end of the message. If the frame check sequence is correct, an acknowledgement is included in the next frame to be sent in the opposite direction. This mechanism allows for re-transmission of un-acknowledged messages, thus increasing the reliability of data transfers throughout the network.
MESSAGE HANDLI~G (OUTSTATION) For each link under its control, the communication controller CCL cycles around each outstation OS under the control of two lists. All low priority outstations are contained in one list and the communication controller CCI, cycles around them, polling for vehicle ENP data, unless interrupted by a higher priority item i.e., a high priority outstation poll, a wanted vehicle request or initialisation/downline loading of an outstation. The last two items are random whereas the hi~h priority outstation poll is under the full control of the communication controller CCL. Each half-second, the communication controller CCL polling task will be flagged to use the hiqh priority outstation list ~ breakin~ into the low priority cycle. When all high priority sites hav~
been polled, the communication controller CC reverts to the low priority cycle again.

MESSAGE HANDLING - (CENTRAL O~FICE) As mess~ges are received over the HDLC links, the communication controller CCL separates the data into buffers for each data validator DV and the supervisory processor SP. To optimise the processing of data from high priority sites, the transfer of clata to the data validator DV over the local area network is synchronised to the receipt of the last message from a high priority site (from all links). Polling for this data is synchronised to a half-second flag.
Messages received from any other central control processor are passed to a task which sets up additional data in the poll request data packets or interrupts the polling sequence to transmit higher priority packets in between poll requests. Down line loading of outstations database(s) is phased so that the polling sequence is not unduly delayed.

'WANTED' LIST HANDLING
A communication controller CCL only receives a message packet from a data validator DV for a 'Wanted' vehicle when an anomaly is detected at a high priority outstation. It is important to get that in~ormation to the outstation q~ickly - to display the data on a police terminal or to get a frame of a picture of the vehicle sent to the central control, so the poll request sequence is interr~pted, to send a special 'wanted' vehicle data packet.

'13 CONFIG~RATION DATA HANDLING AND INITIALISATION
During communication controller CC initialisation, the configuration of all equipment under the control of that communication controller CCL is down-line loaded from the supervisory processor and stored in random access memory. This data includes the configured high priority and low priority outstation lists, communication systems addresses for each outstation ( HDLC network) and central control processor local area network and the configuration data for each outstation ~including interrogator and loop layout configuration).
Whenever an outstation is (re)initialised the communication controller CCL controls both the link set-up procedure and the down-line loading of data. If an outstation is being initialised whilst the system is active, there must be minimal interference with data retrieval from other outstations, so once down-line loading has started, the data packets are interleaved between low priority outstation poll requests (not delaying high priority polling).
~EAL-TIME UPDATES
Whilst ~n-line, the changes to communication controller configuration data are:
a) Change of outstation priority, when a terminal is connected or disconnected; and b) Change of data validator DV address on the local area network, iE processors are substituted.
In the first case, the communication controller CCL

~2~ 3 simply changes the relevant outstation between the high and low priority lists. In the latter case, the supervisory processor SP sends update information to the communication controller CCL, which changes the relevant address for that data validator DV on the local area network.
FAULT DETECTION AND RECOVERY
Apart from carrying out self checks when requested and sending the results to the supervisory processor SP, a communication controller CCL monitors the HDLC links for faults. Each data packet sent to an outstation should be acknowledged by a reply data packet im~ediately. If the reply is corrupted, the frame check se~uence fails to match, or no reply is received for any transmission within a timeout period, the communication controller CCL
retransmits the packet up to twice more. If no acknowledg ment is received by this time, the outstation is marked 'suspect faulty' and the poll sequence continues. A count of consecutive 'suspect fault' indications is maintained each time the outstation is polled, and is cleared when an acknowledgement is received. When the count reaches a limit of say 3, the outstation is marked 'faulty' and the SP informed. Once the supervisory processor SP has recorded the fault, it can only be cleared by an operator (in the Central Office) or enginee~r (from an outstation terminal).
DATA VAI.IDAI'ORS

Concerning the data validators DV, their primary function is to validate vehicle data before preparation of invoices. The data validator DV receives individual vehicle ENP data from the communication controllers CCL
and checks the identity and location of each vehicle before sending the accounting information to the accounts processor AP which records each vehicle's road usage and periodically invoices the owner.
In one arrangement of the system, accounting information is sent to the supervisory processor SP and then to the accounts processor AP over a direct serial link SL. In another arrangement of the system, accounts information is sent to the accounts processor AP over the inter-processor bus IPB.
Whenever the data validator DV fails to confirm the identity or location of a vehicle at a high priority site, it immediately sends a message back to that outstation OS.
At a CCTV outstation this initiates transmission to the central office of a frame of a picture of the vehicle which is suspect. At a manned site the data on the suspect vehicle will be output to the police or maintenance terminal.
In addition, for all sites regardless of priority, if the data validator DV fails to confirm the location toutstation) or security code of the vehicle, the information ttogether with the last ~nown location) is passed on to the supervisory processor SP which attempts to recover the situation ('Anomaly Processiny') or identify 'suspect' vehicles.

These are then added to a 'Wanted' list and also notified to the data validator DV.
Two types of anomaly are passed to the supervisory processor SP for further analysis: an invalid security code for an ENP, or an invalid location (outstation) when compared with the vehicle's last known location. Each of these anomalies may be caused by a vehicle apparently missing one or two outstations through 'rat runs', a faulty outstation, a faulty ENP on the vehicle, or a ro~ue vehicle whose ENP has been tampered with.
The supervisory processor requests vehicles to be marked as 'wanted' and whenever a data validator D~
receives data for such a vehicle, it is sent on to the supervisory processor SP immediately. The data validation processing is illustrated in the flow diagram of Figure 4.
It is necessary to process individual vehicle information as fast as it is arriving at the central control CC, and to provide any control information for the outstations as quickly as possible. To achieve this, a distributed microprocessor system is employed which uses different levels responsible for different functions.
At the lowest level within the central control, communication controllers CCL poll outstations OS
regularly to retrieve individual vehicle information from the road.
As previously mentioned, this information is then buffered for onward transmission to a data validator DV

the selection of data validator DV being dependent upon ~a2~ 3 the vehicle serial number.
A set of data validators DV check each vehicle's information in order to charge the owner for road usage related to the sites (outstations OS) passed. In order to handle 350,000 vehicles, each data validator DV is allocated part of the whole database (in the order of 40-50,000 vehicles, although this may be reduce~ if the local area network can handle more nodes easily). When data is received from a communication controlle~ CCL it is quickly processed and the result passed on to either the accounts processor AP or the supervisory processor SP in accordance with whether the accounts processor interfaces the bus IPB or is served by a serial link SL from the supervisory processor SP respectively. The incidence of invalid data should be such as to keep the loading in the supervisory processor SL low compared to the loading on a data validator DV.
The advantages of using a number of small processors rather than one large one include:
a) Lower overall cost;
b) Lower maintenance costs;
c) Possibility of smaller system initially, with controlled build-up to a lar~er system;
d) Input-output load is distributed;
e) ~ny fault will aEEect only a part oE the systern;
f) No routine maintenance is requirc-d on the data validators DV;
g) The mechanical number/ENP serial number relationship need only he retained in those proce.ssors requiring it, i.e., data validators DV and supervisory processors SP, thereby maximising security by minimising accessibility of this information to operating staff.
OPERATI ON
As data packets are received from communication controllers CCL they are put into high and low priority queues, with the high priority queue being processed at the first available opportunity (when any current processing finishes), in case a response has to be returned to the outstation quickly.
Each vehicle's data are checked for:
i) Correct data validator DV (as routed through from the communication controller CC);
ii) Valid, commissioned ENP (enables access to the vehicle's current database information);
iii) Being 'wanted' (data sent on the supervisory processor SP immediately);
iv) Valid security code (if any); and v) Valid location with reference to the last recorded location.
IE the data was received frorn a high priority site and test (iii) succeeds or any of tests (i,ii,iv or v) fail, informatiorl is sent immecliately to ti-le outstation for appending to a display on a police termillal or to a display at the central control.
To speed the processing, ENPs are distributed evenly throughout each data validators DV memory and a simplemapping from the low order bits of the ENP serial number is used to mi.nimise searches for the actual database entry to a maximum of 30 vehi.cles in each section. Also, table look~up techniques are applied to security code checking (byte orientated) and location-to-location movement validation, to optimise processing time.

MESSAGE HANDLING - SUPERVISORY PROCESSOR AND A~COUNTS
_ . _ Anomalies are passed on to the supervisory processor SP as soon as they are detected (one vehicle per packet) over the local area network. Data forwarded to the supervisory processor SP are the received E~P data and (provided the ENP existed in the DV database) the current database record for the vehicle.
15Accounting information is accumulated in the data validator DV in a large buffer so that larger, infrequent packets can be forwarded to the acco~nts processor when either the data in the buffer reaches a pre-defined size or after a known time since reception of data from the last outstation. Apart from data validator DV
initialisation (down line loading of data validator DV
configuration and database information) the supervisory processor SP sends the following information to a data validator DV:
a) Time synchronisation - a local area network packet broadcast to all central control processors to ensure real time synchronisation (the data validator DV

needs time-of-day to send accounting information);

b) Add a vehicle to the 'Wanted List' together with a reason;
c) Remove an operator-wanted vehicle from the 'Wanted List';
d) Remove a data validator DV-anomoly from the 'Wanted List';
e) Data validated (sending back an anomaly which has been checked out by the S~);
f) Update vehicle database (sending back the most recent data after an anomaly has been corrected by analysing several consecutive packets in the supervisory processor SP);
9) Mark a location 'faulty';
h) ~lear a 'faulty' indication;
5 i) Request a vehicle's current location tin response to an operator command at the supervisory processor SP);
j) Instructions to perform a self-check.
The last two require a specific reply to be sent to the supervisory processor SP. Processing of these data packets is handled at a lower priority than raw vehicle data.
REAL-TI ME UPDATES
Whenever a vehicle's ENP data is validated (either directly in the clata validator DV or via the anomaly processing in the supervisory processor SP), the current database record in the data validator DV is updated with current location and security code indication. The 'Wanted List' and '~aulty Location' markers are also updated as and when directed by the supervisory processor SP .
A basic database change occurs when an ENP is commissioned. ~ere the supervisory processor SP controls the commissioning process and updates the data validator DV database before informing the fitting station that the ENP is accepted.

SUPERVISORY PROCESSO~
Considering the supervisory processor SP, one o its main functions is to commission new ENPS. New vehicle information is sent to the supervisory processor SP from a fitting station and it is checked against the existing database (to ensure there is no duplication of data).
Valid data is then updated in the supervisory processor SP
and the data validator DV and is sent back to the fitting station for confirmation by the operator. Vpon receipt of the confirrnatlon, the ENP is Icommissioned' and the system is ready to accept information from any location.
The supervisory processor SP, manages the resources of all central control CC processors and performs secondary Eunctions that arise ~rom DV data validator operations.
In one arrangement, the accounts processor AP does not inter[ace to the local area network, so all accounting information is routed through the supervisory processor SP, which queues information on a disc store DS, and passes it serially over a 9600 baud direct link SL to the accounts processor AP. This arrangement is not necessary when the accounts processor AP interfaces to the local area network. The supervisory processor SP system is built aro~nd a disc-based operating system because this processor needs to:
a) ~old large amounts of data, for all levels of processor in the system;
b) Store vehicle data over quite long periods of time, for anomaly processing;
0 c) Handle operator communications, via several terminals and d) Maintain information on system status and performance related to the many processors and their databases.
Operator communication OC facilities are provided via the supervisory processor SP, with two visual display units (VDU's) interfacing to the operators in the control room and one hard copy terminal upon which the supervisory processor SP logs all significant events.
The supervisory processor SP contains a real time clock which is used to maintain realtime (synchronised) in all other processors that require it, for example for accounting information, relating CCTV pictures to a time of day and accessing vehicle movements in time.
The supervisory processors SP re-validate E~P data whenever possi~le, identify equipment faults from E~P data analysis, manage datal)ase information, and provide information to the operators in a simple but effective way. The supervisory processor SP uses the local area ~V~ 3 network to ensure that cornmunications between all central control CC processors are maintained and thus all of them are functioning correctly. Changes to system configuration (comrnissioning/de-commissioning of ENPs;
switching to standby processors; adding new equipment or links) are all controlled by the supervisory processor SP
system, so that the central store of all database information is kept up-to date on a disc DS.
The relationship between each vehicle's mechanical number plate (MNP) and ENP serial number is stored in the ~ata validator DV tto identify the MNP from the ENP serial number) ar-,d in the supervisory processor SP.
In the supervisory processor SP only, the inverse relationship is also held (on disc), with ENP being stored against MNP. This enables mapping from an operator-defined ~INP to its corresponding ENP serial number. There is no need for any operator to know any vehiclels ENP
serial number, thus ensuring security of this coded information.

ANOMOLY_PROCESSING
When anomalies are received by the supervisory processor SP, it attempts to re vaLidate the data (security code, location or both). Initially invalid locations are checked using the vehicle's ]ast known location, to discover whether the vehicle has passed througll faulty outstations and to identiEy 'suspect' outstation equipment. If more than one non-faulty outstation exists between the two given locations, the vehicle is added to the 'Wanted List' and a record is kept of all its movements until an operator confirms re-validation.
Invalid security codes cannot be re-validated immediately, so a record is started which keeps track of the vehiclels security code changes and to continue validating the locations. If, after 3 security codes have heen recorded, its position in the code sequence cannot be ascertained, the vehicle :identity is added to the 'Wanted List' as for invalid locations.
For each subsequent recognition of a vehicle on the '~anted List' the data DV sends the latest information to the supervisory processor SP which adds it to the vehicle's record and attempts to re-validate the last 3, say, security code and location parameters. When a re-validation is achieved, the system informs the operator ~ho can display the record of information and, optionally, clear the vehicle from the 'Wanted List'.
When data is re-validated (the supervisory processor SP ensures that both location and security code are correct), the latest data are passed back to the data validatcr DV to update its database and the vehicle is removed from the 'Wanted List' in both supervisory processor SP and data validator DV (unless required by the operator Eor otl~er reasons).
A flow diagram of the anomoly processing/fraud identification is illustrated in ~igure 5. Operator facilities OC are available to manipulate the `Wanted List' and for fault management VDU terminals allow system messages to be displayed in a non-scrolling area of the screen, and operator information to be scrolled using the remainder of the screen.

Claims (27)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A data capture system for the automatic charging of tolls to vehicular users of roads, the capture system comprising, a plurality of vehicle identity data transmitting means each being individually attachable to vehicles, a plurality of roadside vehicle identity data interrogating means linked by a communications network with a central control which includes a plurality of communications control processors, and a plurality of vehicle identity data validating processors which communicate by means of a common inter-processor bus, wherein each data validating processor is allocated a discrete subset of all vehicles handled by the system and wherein upon transmitted vehicle identity data being detected by any one roadside vehicle identity data interrogating means, the vehicle identity data is transmitted through the communications network to a communications control processor and then by way of the common inter-processor bus to the particular data validating processor allocated to the subset of vehicles within which, the detected vehicle identity data is located, whereupon, the detected vehicle identity data is validated for use in enabling the preparation of toll invoices for despatch to the particular vehicle user concerned.

2. A data capture system as claimed in claim 1, in which the vehicle identity transmitting means is electronic number plate apparatus comprising a module incorporating storage means for storing the vehicle identity data and transmitting means for transmitting said vehicle identity data and wherein the vehicle identity data comprises for each individual electronic number plate apparatus, a code representing the unique serial number of the apparatus, the serial number being programmed into the storage means.

3. A data capture system as claimed in claim 2, in which the vehicle identity interrogating means is an outstation comprising an interrogator, a transmission unit, a processor and a plurality of interfaces to local equipment, wherein the outstation is connected to a plurality of inductive receive loops which are capable of electromagnetically coupling with the transmitting means enabling selection of the codes indicative of a vehicle's identity, the code signals being demodulated by the interrogator and passed to the processor for code verification, whereupon the verified code is transmitted from the outstation by the transmission unit.

4. A data capture system as claimed in claim 3, in which one local equipment comprises a closed circuit television (CCTV) system which stores frames of pictures of vehicles in a suspect category which are captured in the CCTV system, wherein the stored picture frames are transmitted to the central control for analysis and/or display upon a message, relating to vehicles in the suspect category, being transmitted from a communication controller to an outstation incorporating a CCTV system.

5. A data capture system as claimed in claim 4, in which the communications network is a cable network, wherein the network is arranged to link the outstations to an inter-processor high-speed bus at the control centre, under the control of the communication controllers and wherein each communications controller incorporates a plurality of outstation channels each of which is connected to a plurality of outstations wherein each communications controller is enabled to control a part of the complete cable network.

6. A data capture system as claimed in claim 5, in which the data validating processors and a supervisory processor are connected to the inter-processor bus, wherein each data validating processor receives, from a communication controller, vehicle data comprising serial number, security code and location (outstation) concerned with its own allocated subset of vehicles exclusively for processing.

7. A data capture system as claimed in claim 6, in which the data validating processor includes means for checking that the serial number is in the range allocated to that particular data validation and including means for sending a message when the check is not confirmed, to the supervisory processor indicating an invalid serial number is being sent.

8. A data capture system as claimed in claim 7, including means operative to determine when the serial number check is confirmed, the memory location in the data validator holding the vehicle's data wherein a check to determine if the electronic number plate identified is in commission, if the check is not confirmed said message sending means being operative, to send a message indicating an invalid serial number is being sent to the supervisory processor.

9. A data capture system as claimed in claim 8, in which when the data validation processor is operative to determine that either the location (outstation) of the vehicle with respect to its last stored location is invalid or the security code with respect to the last stored security code is invalid, said message sending means is operative to send, in each case respectively, a message to the supervisory processor to initiate anomoly processing.

10. A data capture system as claimed in any of claims 7, 8 or 9 in which, when the vehicle data being processed is from a high priority outstation, a message sending meant is operative to send a message to that outstation to;
a) display the vehicle data at the police or maintenance terminal, or b) to append the vehicle data to a frame of a picture of the vehicle.

11. A data capture system as claimed in claim 6, in which when the data validating processor determines that the serial number location (outstation) and the security code are valid, a message sending means is operative to send the mechanical registration number and location to an accounts processor for toll charging purposes.

12. A data capture system as claimed in claim 11 in which the system is operative to route accounting information through the supervisory processor, and said system includes means for queuing the accounting information on a disc store and a serial direct link for transmitting the accounting information to the accounts processor.

13. A data capture system as claimed in claim 11, including means for routing the accounting information over the inter-processor bus to the accounts processor.

14. A data capture system as claimed in claim 7, in which means are provided within the supervisory processor which arranges for the vehicle identity to be logged on a 'Wanted List' when the supervisory processor receives a message indicating an invalid serial number.

15. A data capture system as claimed in claim 9, in which upon the supervisory processor receiving anomoly data from the data validating processor, a processing means within the supervisory processor performs a process for revalidation of the data whereby in respect of invalid locations the vehicle's last location is checked against its current location to discover whether the vehicle passed through faulty outstations and, if it is determined that more than one non-faulty outstation exists between two given locations, a logging means logs the vehicle identity on a 'Wanted List'.

16. A data capture system as claimed in claim 9, in which, upon the supervisory processor receiving anomoly data from the data validating processor, a processing means within the supervisory processor performs a process for revalidation of the data, whereby a record is started in a memory means which keeps track of the security code changes with continued validation of locations, the processing means being operative, following the recordal of three security codes in which the position in the code sequence can not be ascertained, to arrange for the logging means to log the vehicle identity on a 'Wanted List'.

17. A data capture system as claimed in claims 15 or 16 in which the supervisory processor is operative to return revalidated data to the relevant data validation processor whereupon the validation processor is operative to update its records and means are provided for removing the vehicle identity from the 'Wanted List'.

18. A data capture system as claimed in any one of claims 2 to 4, in which the storage means is a fuse-link PROM.

19. A data capture system as claimed in any one of claims 5 to 7, in which the storage means is a fuse-link PROM.

20. A data capture system as claimed in claim 8 or 9, in which the storage means is a fuse-link PROM.

21. A data capture system as claimed in any one of claims 11 to 13, in which the storage means is a fuse-link PROM.

22. A data capture system as claimed in any one of claim 14 to 16, in which the storage means is a fuse-link PROM.

23. A data capture system as claimed in any one of claims 2 to 4, in which the transmitting means comprises an aerial.

24. A data capture system as claimed in any one of claims 5 to 7, in which the transmitting means comprises an aerial.

25. A data capture system as claimed in claim a or 9, in which the transmitting means comprises an aerial.

26. A data capture system as claimed in any one of claims 11 to 13, in which the transmitting means comprises an aerial.

27. A data capture system as claimed in any one of claims 14 to 16, in which the transmitting means comprises an aerial.