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(11) | EP 1 271 446 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Speed trap detection and warning system |
| (57) There is provided an apparatus and method for alerting the driver of a vehicle to
a speed trap by monitoring the position of the vehicle against one or more databases
of speed trap positions to determine whether the vehicle is within a predetermined
distance of a speed trap. To reduce the incidence of false alarms, the database(s)
or the data therein distinguishes between speed traps situated on a motorway and speed
traps situated on other types of roads. When the vehicle is travelling on a motorway,
the driver is alerted if the vehicle approaches within a predetermined distance of
a motorway speed trap, but is not alerted if the vehicle travels within a predetermined
distance of a non-motorway speed trap. |
[0001] This invention relates to a speed trap detection and warning system for alerting the driver of a vehicle to the presence of a nearby speed trap (such as a speed camera, radar gun detector etc) and in particular to a system which provides a low false alarm rate.
[0002] Speed traps of a number of different types are used in increasing numbers by law enforcement authorities around the world. These include active traps (Gatso cameras, radar guns, laser guns, etc) and passive traps (VASCAR type detectors, SPECS type detectors, etc).
[0004] For example, radar detectors for use in vehicles are known. These work by detecting the radar signals from a radar-operated speed trap and provide an alert that radar signals are incident on the vehicle. Radar detectors suffer from the problem, however, that they may be set off by things other than speed traps which operate on similar frequencies. For example, traffic lights, building alarm systems and petrol stations may trigger a radar detector. The radar detector may therefore provide many false alarms, thereby reducing the usefulness of the detector since it is irritating to the driver and encourages the driver to undertake rapid braking regularly and, from the point of view of other road users, at random.
[0005] EP-A-0789344 discloses a device which stores the locations of speed traps in a database, monitors the location of the vehicle in which it is installed for example using satellite GPS (Global Positioning System) techniques, compares the vehicle location against the stored speed trap locations, and warns the driver if the vehicle travels within a predetermined distance of a speed trap.
[0006] However, the inventor in the present application has found that this type of device, too, suffers from the problem of false alarms.
[0007] In particular, the inventor in the present application has realised that a driver is often alerted to a speed trap located on a nearby road (rather than the one on which he is travelling) due to inaccuracies in calculating the position of the vehicle. The inventor has also realised that this is a particular problem because many roads run nearby, or over, motorways.
[0008] It is therefore an object of the present invention to address one or more of the above problems.
[0009] According to the present invention, there is provided an apparatus and method for alerting the driver of a vehicle to a speed trap by monitoring the position of the vehicle against one or more stored speed trap databases to determine whether the vehicle is within a predetermined distance of a speed trap. To reduce the incidence of false alarms, the database(s) or the data therein distinguishes between speed traps situated on a motorway and speed traps situated on other types of roads. When the vehicle is travelling on a motorway, the driver is alerted if the vehicle approaches within a predetermined distance of a motorway speed trap, but is not alerted if the vehicle travels within a predetermined distance of a non-motorway speed trap.
[0010] Optionally, when the vehicle is travelling on a non-motorway road, the driver is alerted if the vehicle approaches within a predetermined distance of a non-motorway speed trap, but not when the vehicle approaches a motorway speed trap.
[0011] Instructions about whether the vehicle is travelling on a motorway may be input manually (for example by the driver) and/or automatically based on vehicle location and/or speed.
[0012] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 shows a road network, including a motorway and speed traps, and a vehicle having a speed trap detection and warning system travelling through the road network;
Figure 2 shows a perspective view of the speed trap detection and warning system from the vehicle in Figure 1;
Figure 3 shows a block diagram of the functional components of the speed trap detection and warning system;
Figure 4, comprising Figure 4A and Figure 4B, shows a flow diagram of the method of operation of the speed trap detection and warning system in a first embodiment; and
Figure 5, comprising Figure 5A and Figure 5B, shows a flow diagram of the method of operation of the speed trap detection and warning system in a second embodiment.
First Embodiment
[0013] Referring to Figure 1, a road network comprises a motorway 1 and a plurality of non-motorway roads 2,3 along which a plurality of speed traps (in this example, fixed speed cameras) 4,5,6 are deployed.
[0014] Driving along the motorway 1 is a vehicle 9, which is equipped with a speed trap detection and warning unit 11.
[0015] As will be explained in more detail below, the speed trap detection and warning unit 11 has stored within it, among other things, the satellite GPS (Global Positioning System) positions of the speed traps 4,5,6, together with data defining the road number (which defines whether the road is a motorway or not), the respective speed limit for the part of the road at which each speed trap 4,5,6 is situated, and the direction of travel in which the speed trap is operational (that is, the direction in which each speed trap is pointing to record speeding vehicles).
[0016] In this embodiment, the speed trap detection and warning unit 11 uses signals from satellites 7 belonging to the NAVSTAR (NAVigation System with Time And Ranging) GPS system to determine its position, speed and direction of travel (and hence the position, speed and direction of travel of the vehicle 9), compares these parameters with the positions, operating directions and speed limits of the speed traps 4,5,6 stored in its internal database, and provides a warning to the driver of the vehicle 9 when a speed trap 4,5,6 which is operational in the direction of travel of the vehicle 9 is being approached and the speed of the vehicle 9 exceeds the speed limit at the speed trap 4,5,6. In addition, as will be explained below, the speed trap detection and warning unit 11 has a "motorway operating mode" for selection when the vehicle is travelling on a motorway. In the motorway operating mode, speed traps 5,6 on non-motorway roads 2,3 are disregarded, and the driver is warned when a motorway speed trap 4 is being approached (which is operational in the direction of travel of the vehicle 9 and the speed of the vehicle 9 exceeds the speed limit at the speed trap 4), but not when a non-motorway speed trap 5,6 is being approached.
[0017] The speed trap detection and warning unit 11 is arranged to provide any warning well in advance of the speed trap 4,5,6 enabling the driver to reduce speed progressively, thereby increasing safety for the driver and other road users.
[0018] Referring now to Figure 2, the speed trap detection and warning unit 11 comprises a display and processing unit 15 and a power connector 17.
[0019] The display and processing unit 15 comprises an antenna 23 for receiving signals from the satellites 7, processing hardware and memory (not shown in Figure 2, but described below) to process the received signals, a liquid crystal display 25 for displaying information to a user, a speaker 27 for providing audible signals to a user and input buttons 29 for the input of instructions by a user to control the speed trap detection and warning unit 11. In this embodiment, the input buttons 29 include one or more buttons for the driver to press to activate and deactivate the motorway operating mode when the vehicle 9 joins and leaves a motorway 1, respectively.
[0020] In addition, a telephone lead socket 31 is provided for connecting the speed trap detection and warning unit 11 to a remote database for loading and updating information about, inter alia, the positions of speed traps 4,5,6, the speed limits thereat and the operational directions thereof as further speed traps are added to the road network.
[0021] The power connector 17 comprises an adapter for drawing power from a motor vehicle cigarette lighter socket (not shown).
[0022] Figure 3 is a block diagram showing the functional elements of the display and processing unit 15.
[0023] Referring to Figure 3, the antenna 23 receives signals from the GPS satellites 7 and sends them to a GPS receiver/decoder 41. The GPS receiver/decoder 41 is a conventional component, such as the Trimble Navigation Lassen™ - SK8 Embedded GPS Core Module, which processes the received GPS signals and outputs what is known in the art as a "navigation solution", which comprises a data stream defining the position, speed and direction of travel of vehicle 9.
[0024] The navigation solution from the GPS receiver/decoder 41 is passed to a central processing unit (CPU) 43 which operates according to instructions stored in an operating instruction store 45 to perform processing as will be described below. Working memory 51 is provided for the CPU 43 to use while performing processing.
[0025] The GPS positions of the speed traps 4,5,6 together with known positions at which it is common for police to operate a mobile speed trap (such as a radar gun or laser gun) are stored in a speed trap database 49. Also stored in the speed trap database 49 in this embodiment is data defining the road speed limit at each speed trap location, the type of each speed trap (that is, the detection method by which it operates and/or whether it is a fixed or a mobile site), the direction of travel in which each speed trap is operational and the number of the road on which each speed trap is located (which also defines whether the speed trap is a motorway speed trap or a non-motorway speed trap).
[0026] As will be described below, in use, CPU 43 compares the navigation solution in the data from the GPS receiver/decoder 41 with the data from the speed trap database 49, and displays information to the driver of the vehicle 9 via the display 25 and/or generates an audible alert through the speaker 27.
[0027] Input buttons 29 are provided for the user to select the operating mode of the speed trap detection and warning unit 11 (including the motorway operating mode), and to change operating parameters such as the volume of audible alerts and the information to be displayed on the screen.
[0028] More particularly, in this embodiment, one of the buttons 29 is arranged to set the speed trap detection and warning unit 11 into motorway operating mode when it is pressed by the driver (when the vehicle 9 joins a motorway 1) and another of the buttons is arranged to cancel the motorway operating mode when it is pressed by the driver (when the vehicle 9 leaves the motorway 1).
[0029] A telephone interface 53 is provided for connecting with a remote database 55, which is not a part of the speed trap detection and warning unit 11, via the telephone lead socket 31. That is, a cable (not shown) is used to connect between the telephone lead socket 31 and a telephone network (not shown) so as to connect the speed trap detection and warning unit 11 to a remote database 55 which is also connected to the telephone network. The remote database 55 stores data for storage in the speed trap database 49 defining the position of each speed trap 4,5,6 the road number of the road on which each speed trap is located, the speed limit of the road for the position at which the speed trap is located, the operating direction(s) of each speed trap and the type of speed trap. The data in database 55 is updated when an additional speed trap is added to the road network or when an additional site at which a mobile speed trap is frequently used becomes known, when new roads are added to the road network 1 or when the speed limit for an existing road is changed. The telephone interface 53 allows the CPU 43 to execute the update database function to use information from the remote database 55 to replace the data stored in the speed trap database 49.
[0030] The processing operations of the speed trap detection and warning unit 11 will now be described with reference to Figure 4.
[0031] At step S4-2 the GPS receiver/decoder 41 generates a navigation solution and transmits it to the CPU 43. The CPU 43 then extracts from the navigation solution the current speed at which the speed trap detection and warning unit 11 (and hence the vehicle 9) is travelling, the position of the vehicle 9 and the direction of travel of the vehicle 9.
[0032] At step S4-4 the CPU 43 checks to determine whether a navigation solution has been generated. A navigation solution may not be generated for example whilst the vehicle 9 is within a road tunnel, or if landscape or architectural features prevent the GPS receiver/decoder 41 from receiving enough satellite signals to generate a navigation solution. In addition, when the speed trap detection and warning unit 11 is first switched on after a period of non-operation, the GPS receiver/decoder 41 may require up to a few minutes to generate a first navigation solution. If it is determined at step S4-4 that no navigation solution has been generated, then at step S4-6 the CPU 43 causes a warning to be displayed on display 25 and the process returns to step S4-2. On the other hand, if it is determined at step S4-4 that a navigation solution has been generated, then the process continues to step S4-8.
[0033] At step S4-8, the CPU 43 causes the current vehicle speed to be displayed on the display 25. The current vehicle speed continues to be displayed on the display 25 until, on a future cycle, the speed is determined to have changed, at which time the display 25 is updated to display the new current vehicle speed. Accordingly, the display of the current vehicle speed on the display 25 is updated continuously in accordance with the operational cycle rate, which in this embodiment, is once per second.
[0034] At step S4-10, CPU 43 compares the current location of the vehicle 9 as determined from the navigation solution generated at step S4-2 to the stored locations of speed trap sites stored in the speed trap database 49.
[0035] At step S4-12, CPU 43 determines whether any speed trap sites are within a first predetermined distance of the vehicle 9, which, in this embodiment is set to 500 metres. If no speed trap sites are within the first predetermined distance of the vehicle 9, processing returns to step S4-2 to await the generation of a new navigation solution for processing.
[0036] On the other hand, if it is determined at step S4-12 that one or more speed trap sites are within the first predetermined distance of the vehicle 9, then, at step S4-14, CPU 43 determines whether the motorway operating mode is currently set.
[0037] If it is determined at step S4-14 that the motorway operating mode is set, then, at step S4-16, CPU 43 determines whether any of the speed traps identified at step S4-12 is a motorway speed trap. More particularly, in this embodiment, CPU 43 determines whether each of the speed traps identified at step S4-12 is a motorway speed trap by reading the data stored in speed trap database 49 defining the road number of the road on which the speed trap is located and determining whether the road number is prefixed by the letter "M" (indicating a motorway number).
[0038] If it is determined at step S4-16 that none of the speed traps identified at step S4-12 is a motorway speed trap, then processing returns to step S4-2 to await the generation of a new navigation solution for processing.
[0039] On the other hand, if it is determined at step S4-16 that at least one of the speed traps is a motorway speed trap, or if it is determined at step S4-14 that the motorway operating mode is not selected, then processing proceeds to step S4-18.
[0040] By performing the processing at steps S4-14 and S4-16 in the way described above, a speed trap identified at step S4-12 (that is, a speed trap towards which the vehicle 9 has approached within a predetermined distance) is not processed further if the motorway operating mode has been selected and the speed trap is situated on a non-motorway road. In this way, false alarms caused by non-motorway speed traps when the vehicle 9 is travelling on a motorway 1 are eliminated. Thus, with reference to Figure 1, when vehicle 9 is travelling on motorway 1 the driver is not alerted when the vehicle 9 approaches within a predetermined distance of speed trap 5 or speed trap 6. However, as will be explained below, the driver may be alerted when the vehicle 9 approaches speed trap 4.
[0041] At step S4-18, CPU 43 compares the direction of travel of the vehicle 9 (previously determined at step S4-2) to the location of the speed trap site(s) identified at step S4-12 (it being noted that the vehicle direction of travel is compared against the location of only motorway speed traps identified at step S4-12 if it was determined at step S4-14 that the motorway operating mode is currently selected).
[0042] At step S4-20, CPU 43 determines whether or not the vehicle 9 is travelling towards any of the identified speed trap sites. More particularly, in this embodiment, CPU 43 determines whether the distance between the vehicle and a speed trap site is decreasing (in which case it is determined that the vehicle is travelling towards the speed trap) or increasing (in which case it is determined that the vehicle is travelling away from the speed trap).
[0043] If the vehicle 9 is not travelling towards a speed trap site, it is still necessary to monitor the speed of the vehicle 9 after the speed trap has been passed if the vehicle is still within the operating range of the trap, since the trap may still detect a speeding vehicle within this range. Therefore, to take account of this, at step S4-22, CPU 43 determines whether the vehicle is still within a second predetermined distance of the speed trap site. The second predetermined distance represents the range over which the speed trap may operate, and, in this embodiment, is set to 100 metres.
[0044] If it is determined at step S4-22 that the vehicle 9 is beyond the second predetermined distance of the speed trap site then the processing returns to step S4-2 and a new navigation solution is processed.
[0045] On the other hand, if it is determined at step S4-20 that the vehicle 9 is travelling towards the speed trap site or it is determined at step S4-22 that the vehicle is still within the second predetermined distance of the speed trap site, then the processing proceeds to step S4-24.
[0046] At step S4-24, CPU 43 compares the direction of travel of the vehicle 9 to the direction in which the speed trap is operational. This comparison is to ensure that the driver of the vehicle 9 is not alerted when the vehicle 9 is approaching a speed trap which cannot trap the vehicle 9 because the trap is directed or positioned to trap vehicles which are approaching the speed trap from a direction different to the direction of travel of the vehicle 9 (for example, the speed trap may be positioned on the opposite side of the road to the side on which vehicle 9 is travelling, so as to trap vehicles travelling in the opposite direction).
[0047] At step S4-26, CPU 43 determines whether the vehicle 9 is travelling in a direction in which the speed trap is operational.
[0048] If it is determined at step S4-26 that the vehicle 9 is not travelling in a direction in which the speed trap is operational, processing returns to step S4-2 and a new navigation solution is processed.
[0049] On the other hand, if it is determined at step S4-26 that the vehicle 9 is travelling in the direction in which the speed trap is operational, then the processing proceeds to step S4-28.
[0050] At step S4-28, CPU 43 compares the speed of travel of the vehicle 9 (previously determined at step S4-2) to the road speed limit at the speed trap site stored in speed trap database 49. It is then determined at step S4-30 whether the speed of travel of the vehicle 9 is greater than the speed limit at the speed trap site.
[0051] If the speed of travel is determined at step S4-30 to be less than the speed limit of the speed trap site, then the processing returns to step S4-2 and a new navigation solution is processed.
[0052] On the other hand, if it is determined at step S4-30 that the speed of travel of the vehicle 9 is greater than the speed limit at the speed trap site, then, at step S4-32, CPU 43 causes an audible alarm to be emitted from the speaker 27 and causes the speed limit, type of speed trap and road number at the speed trap site to be displayed on display 25 so that the user can compare his current speed, as displayed on the display 25 in step S5-4, to the speed limit at the speed trap site and adjust the speed of the vehicle 9 accordingly. The processing then returns to step S4-2 and a new navigation solution is processed.
Second Embodiment
[0054] The components of the second embodiment and the processing operations performed thereby are the same as those of the first embodiment, with the exception of the structure of the speed trap database 49 and the processing operations performed to determine which speed traps are a threat to the vehicle 9 based on whether the motorway operating mode is selected or not.
[0055] The differences between the second embodiment and the first embodiment will now be described.
[0056] In the first embodiment, at steps S4-10 and S4-12, all of the speed trap locations stored in speed trap database 49 are searched to identify any speed trap which is within a predetermined distance of the vehicle 9. That is, the locations of both motorway speed traps and non-motorway road speed traps are searched. In the subsequent processing in the first embodiment at steps S4-14 and S4-16, non-motorway speed traps identified at steps S4-10 and S4-12 are discarded if the motorway operating mode is set.
[0057] In the second embodiment, on the other hand, the speed trap database 49 is replaced by two separate speed trap databases - one storing data relating to motorway speed traps and one storing data relating to non-motorway road speed traps.
[0058] The way in which processing is performed in the second embodiment using these two speed trap databases will now be described with reference to Figure 5.
[0059] In Figure 5, steps S5-2 to S5-8 are the same as steps S4-2 to S4-8, and steps S5-18 to S5-32 are the same as steps S4-18 to S4-32 in the first embodiment. Accordingly, these steps will not be described again here, and instead, only the processing operations which are different to those performed in the first embodiment (that is steps S5-10 to S5-16) will be described.
[0060] Before searching any database, at step S5-10 in the second embodiment, CPU 43 determines whether the motorway operating mode is currently selected.
[0061] If it is determined at step S5-10 that the motorway operating mode is selected, then, at step S5-12, CPU 43 compares the vehicle's current location (determined at step S5-2) with the stored locations of speed traps in the motorway speed trap database.
[0062] On the other hand, if it is determined at step S5-10 that the motorway operating mode is not selected, then, at step S5-14, CPU 43 compares the vehicle's current location with the speed trap locations stored in the non-motorway speed trap database.
[0063] In this way, a decision about which database to search is made depending upon whether or not the motorway operating mode is selected. Consequently, the processing operations and time needed to carry out the search are reduced since only a subset of all of the speed trap locations are searched (that is, either the locations of motorway speed traps or the locations of non-motorway speed traps). In addition, the processing in the second embodiment ensures that the driver does not receive false alarms from non-motorway speed traps 5,6 when vehicle 9 is travelling on motorway 1, and further ensures that the driver does not receive false alarms from motorway speed trap 4 when vehicle 9 is travelling on a non-motorway road 2,3.
[0064] At step S5-16, CPU 43 determines whether any speed trap site is within a first predetermined distance of the vehicle 9. Processing then proceeds in the same way as described above in the first embodiment.
[0066] For example, in the embodiments described above, the location of the vehicle 9 is determined using GPS processing. However, instead, any radio navigation system providing sufficient accuracy in determining position may be utilised. For example, GLONASS (the Russian equivalent to GPS) or GNSS (a proposed new satellite new navigation system) could be used instead of GPS to provide a navigation solution. Alternatively, the location of the vehicle 9 may be determined using signals transmitted between a device such as a mobile telephone in the vehicle 9 and a plurality of fixed locations. More particularly, a positioning technique may be used such as that utilised in the CURSOR system operated by Cambridge Positioning Systems Limited and described in EP 0303371, WO97/11384, WO99/11086 and WO99/21028. Further, European Telecommunications Standards Institute document ETSI TS 101 528 sets out the standard for GSM Enhanced Observed Time Difference (EOTD) location services as used in Cambridge Positioning Systems CURSOR system and other similar systems. Alternatively, the position of vehicle 9 may be calculated by an in-vehicle system for monitoring the displacement of the vehicle from a starting position. Such a system may comprise, for example the vehicle's mileometer to measure distance travelled and a magnetic compass, gyroscope etc to measure changes in direction.
[0067] In the embodiments above, the data in the speed trap database 49 is updated from a remote database via a communications network. However, instead, the data may be updated by providing a storage device (such as a cartridge, disk, etc) storing the data for insertion into the speed trap detection and warning unit 11. In addition, or instead, data could be entered manually into the database 49, for example by typing with a keyboard.
[0068] In the above embodiments, it is described with reference to Figures 4 and 5 to perform a check at steps S4-22 and S5-22 whether the vehicle is still within a second predetermined distance of a speed trap after the vehicle has passed the speed trap. However, this step may be omitted as the driver of the vehicle 9 will likely be aware that a typical speed trap 4,5,6 detects speeding vehicles at a position past the speed trap.
[0069] Although it is described with reference to Figures 4 and 5 that the driver is alerted only if the speed of travel of the vehicle 9 is greater than the speed limit at the speed trap site, it is possible to omit this function (for example, a facility may be provided for the user to switch it ON/OFF) and alert the driver every time a speed trap is being approached which is operational in the direction of travel of the vehicle irrespective of the speed of vehicle 9.
[0070] Similarly, it is described with reference to Figures 4 and 5 that the driver is only alerted if the speed trap which is within the predetermined distance of the vehicle is operational in the direction of travel of the vehicle. However, it is possible to omit this function (for example a facility may be provided for the user to switch it ON/OFF).
[0071] Although it has been described in the above embodiments with reference to Figures 4 and 5 to display the road number of the road on which the vehicle 9 is travelling at steps S4-32 and S5-32, this is not essential and may be omitted.
[0072] In the above embodiments, it has been described to store the type of each speed trap for display to the user as the vehicle 9 approaches a trap. However, this function is not essential and may be omitted.
[0073] In the embodiments described above, the motorway operating mode of the speed trap detection and warning unit 11 is activated and deactivated using one or more of the buttons 29. To remind the driver to deactivate the motorway operating mode when the vehicle 9 leaves a motorway, the CPU 43 may be arranged to monitor the vehicle speed calculated at step S4-2 or step S5-2 and to sound an audible alarm when the vehicle speed drops below a predetermined value indicative that the vehicle 9 is no longer on the motorway (for example 25 miles per hour).
[0074] As a modification, the motorway operating mode may be automatically activated, deactivated or both activated and deactivated without input from the driver. For example, a location indicative that a vehicle is joining a motorway, such as a location very near every motorway junction entry slip road (for example ten metres onto the motorway from the end of the slip road, or a position on the actual slip road itself) may be stored in the speed trap detection and warning unit 11. CPU 43 may then be arranged to compare the location of the vehicle 9 calculated at step S4-2 or step S5-2 with the stored motorway entry positions, and to activate the motorway operating mode if it is determined that the vehicle 9 passes such a location. Similarly, locations indicative that a vehicle is leaving a motorway, such as the locations of every motorway junction exit slip road or a location nearby which the vehicle 9 must pass when exiting a motorway may be stored in the speed trap detection and warning unit 11 and the motorway operating mode may be deactivated when CPU 43 determines that the vehicle 9 has passed such a point.
[0075] It would also be possible to store bearing information for each motorway operating mode "activation" and "deactivation" point, and the CPU 43 may be arranged to activate the operating mode or de-activate the operating mode only if the vehicle 9 passes an activation/deactivation point and is travelling in a direction within an allowable bearing range based on the stored bearing information.
[0076] In the first embodiment described above, data is stored in the speed trap database 49 defining the respective road number on which each speed trap is located. This data is used at step S4-16 to determine whether a speed trap identified at step S4-12 is located on a motorway. More particularly, in the first embodiment, the data defining the road number is read to determine whether it begins with the letter "M", indicating that the road is a motorway. However, this method of determining whether a speed trap is located on a motorway assumes that the road number of each motorway is prefixed by the letter "M" and that all non-motorway roads are not prefixed by the letter "M" (as is the case in the United Kingdom). In some countries, a letter other than the letter "M" may be used to identify motorways, and the processing must therefore be modified accordingly. Further, in some countries it may not be possible to determine whether a road is a motorway by reading the road number. In such a case, additional data may be stored in speed trap database 49 defining whether each respective road is a motorway. For example, an additional field may be provided in the database for each speed trap defining whether or not the speed trap is located on a motorway. The data in the additional field may then be read at step S4-16 to determine whether the speed trap is located on a motorway.
[0077] In the embodiments described above, all of the components of the speed trap detection and warning unit are provided within the unit 11 carried by vehicle 9. However, instead, the components may be split between a unit carried in vehicle 9 and one or more separate processing apparatus at a remote fixed location or locations. For example, the speed trap database 49 may be stored at a remote processing apparatus which communicates with the apparatus in vehicle 9 by via a mobile telephone link. Other divisions of components are also possible.
signal processing means for receiving signals and for processing the received signals to generate location data defining the location of the vehicle;
at least one database configured to store data defining the respective location of each of a plurality of speed traps;
comparing means for comparing the location determined from the signals with the stored speed trap locations to determine whether the vehicle is within a predetermined distance of a speed trap; and
alerting means for alerting a user if a speed trap is within a predetermined distance of the vehicle;
wherein:the system is operable to distinguish between speed traps located on a motorway and speed traps which are not located on a motorway; and
the system is operable in different operating modes such that, in a first of the modes, the alerting means does not alert the user if each speed trap within the predetermined distance of the vehicle is a non-motorway speed trap.
means for determining the speed of the vehicle; and
means for prompting the user to change to a different operating mode if the system is operating in the first mode and the vehicle speed falls below a threshold value.
means for storing data defining the respective location of each of a plurality of first operating mode activation positions; and
mode activation means for setting the system to operate in the first operating mode;
and wherein:
the comparing means is arranged to compare the determined vehicle location with the stored first operating mode activation locations; and
the mode activation means is arranged to set the system to operate in the first operating mode if the comparing means determines that the vehicle has passed an activation location.
means for storing data defining the respective location of each of a plurality of first operating mode de-activation positions; and
mode de-activation means for de-activating the first operating mode and for causing the system to operate in a different operating mode;
and wherein:
the comparing means is arranged to compare the determined vehicle location with the stored first operating mode de-activation locations; and
the mode de-activation means is arranged to de-activate the first operating mode, thereby causing the system to operate in a different operating mode, if the comparing means determines that the vehicle has passed a de-activation location.
signal processing means for receiving signals and for processing the received signals to generate location data defining the location of the vehicle;
at least one database configured to store data defining the respective location of each of a plurality of speed traps and data defining whether each speed trap is located on a motorway or not;
comparing means for comparing the location determined from the signals with the stored speed trap locations to determine whether the vehicle is within a predetermined distance of a speed trap;
means for determining whether or not a speed trap identified by the comparing means is located on a motorway in dependence upon the stored data associated with the identified speed trap; and
alerting means for alerting a user if a speed trap is within a predetermined distance of the vehicle;
wherein:the system is operable in different operating modes such that, in a first of the modes, the alerting means does not alert the user if each speed trap within the predetermined distance of the vehicle is not located on a motorway.
signal processing means for receiving signals and for processing the received signals to generate location data defining the location of the vehicle;
at least one database configured to store data defining the respective location of each of a plurality of speed traps, the speed traps comprising speed traps located on a motorway and speed traps not located on a motorway, and the database(s) being configured to allow motorway speed trap data to be searched separately from non-motorway speed trap data;
comparing means for comparing the location determined from the signals with the stored speed trap locations to determine whether the vehicle is within a predetermined distance of a speed trap; and
alerting means for alerting a user if a speed trap is within a predetermined distance of the vehicle;
wherein:the system is operable in different operating modes such that, in a first of the modes, the comparing means is arranged to compare the determined vehicle location with only the motorway speed trap data to determine if the vehicle is within a predetermined distance of a speed trap which is located on a motorway.
signal processing means for receiving signals and for processing the received signals to generate location data defining the location of the vehicle;
at least one database configured to store data defining the respective location of each of a plurality of speed traps located on different types of roads;
mode setting means for setting different operating modes of the system;
road type determining means for determining in dependence upon the operating mode set by the mode setting means the road type(s) for which speed traps are a threat to the vehicle;
comparing means for comparing the location determined from the signals with stored speed trap locations to determine whether the vehicle is within a predetermined distance of a speed trap; and
alerting means for alerting a user if a speed trap is within a predetermined distance of the vehicle;
wherein:the system is controlled to prevent the user from being alerted to speed traps unless they are located on a road type determined by the road type determining means to be a threat.
processing signals to generate location data defining the location of the vehicle;
comparing the location determined from the signals with stored data defining the respective location of each of a plurality of speed traps to determine whether the vehicle is within a predetermined distance of a speed trap;
determining whether or not each speed trap identified in the comparing step is located on a motorway in dependence upon stored data associated with the identified speed trap(s); and
alerting a user if a speed trap is within a predetermined distance of the vehicle and is located on a motorway, but not alerting the user if each speed trap within the predetermined distance of the vehicle is a non-motorway speed trap.
processing signals to generate location data defining the location of the vehicle;
determining which operating mode of the processing apparatus is set;
in dependence upon the operating mode of the processing apparatus, selecting a database of stored data to be searched by selecting between a database storing data defining the respective location of each of a plurality of speed traps located on motorways and a database storing data defining the respective location of each of a plurality of speed traps located on non-motorway roads;
comparing the determined location of the vehicle with the data in the selected database to determine whether the vehicle is within a predetermined distance of a speed trap; and
alerting a user if a speed trap defined in the stored searched data is determined to be within a predetermined distance of the vehicle.
setting an operating mode of the apparatus from a plurality of selectable modes;
determining in dependence upon the set operating mode the road type(s) for which speed traps are a threat to the vehicle;
processing signals to generate location data defining the location of the vehicle;
comparing the determined vehicle location with stored data defining the respective location of each of a plurality of speed traps; and
alerting the user if a speed trap located on a road type determined to be a threat to the vehicle is determined to be within a predetermined distance of the vehicle, but not alerting the user if each speed trap within the predetermined distance of the vehicle is a speed trap located on a road type determined to be a non-threat to the vehicle.