GB2434931A

GB2434931A - Traffic information device

Info

Publication number: GB2434931A
Application number: GB0601971A
Authority: GB
Inventors: Lee Coleman
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2006-02-01
Filing date: 2006-02-01
Publication date: 2007-08-08
Anticipated expiration: 2026-02-01
Also published as: GB2434931B; GB0601971D0

Abstract

A navigation system is provided that comprises: inputs for receiving data representing traffic information from a number of service providers; a processor arranged to select traffic information from one of the service providers based on a priority list; and outputs for providing traffic data from the chosen service provider to a user. The priority list comprises a table of Traffic Message Channel (TMC) services that are ranked by service quality and the service selected may not necessarily be the service with the strongest signal strength. Keywords: Radio Data System, RDS, TMC, Digital Radio, DAB, Transport Protocol Experts Group, TPEG.

Description

TRAFFIC INFORMATION DEVICE

Field of the invention

The present invention relates to a traffic information device for a navigation system and in particular, but not exclusively, relates to a navigation device that receives traffic data over a Radio Data Service FM broadcast.

Background to the invention

The development of the Radio Data System (RDS) for VHF/FM broadcasts started some 20 years ago in the European Broadcasting Union, EBU. The system has been on the market since 1987 and forms part of the standard equipment of most radio receivers.

The use of RDS broadcasts makes the use of radio receivers, especially car radios, much more user friendly in environments where a transmitter network supports a number of alternative frequencies (AF). RDS-enabled receivers generally display the programme service name (PS) on an eight character alpha-numerical display and use transmitter frequency information (which is traditionally displayed on non-RDS

radios) in the background.

For many years vehicle users have enjoyed the possibility of receiving traffic information through their car radios with RDS using the Travel Programme (TP) and Travel Announcement (TA) flags. Travel information is broadcast for motorists, identified in parallel with the ART system (a broadcast system for motorists), with the corresponding RDS features TP/TA.

With more and more people taking to the roads, though, and the increase in traffic infrastructure and congestion, the provision of easy, relevant and up-to-the-minute traffic information services has taken on an even greater importance and ART is being replaced on a European scale by the digitally coded Traffic Message Channel (TMC) system. This more recent development of RDS is planned to be introduced all over Europe.

RDS-TMC (Radio Data System-Traffic Message Channel) is an effective way of broadcasting traffic and travel information services. It provides traffic information services, transmitted quickly via automatic traffic data collection and automated message generation, which can be delivered and continuously updated without interrupting a radio broadcast. Based on European (CEN) standards, the service also enables drivers in a foreign country to receive information in their native tongue.

RDS-TMC uses a TMC unit, an advanced radio or in-vehicle navigation system which decodes the incoming data and communicates it via speech announcement or on-screen display. Information can be received and recalled at any time, in any language, and be selected according to individual criteria such as route or area. The advantage of RDS-TMC over traditional traffic radio broadcasts is its continuous update capabilities and the fact that drivers can select and receive only the information which they require.

For an RDS-TMC service, data on traffic flows and weather are collected at centralised traffic information centres and passed to a TMC traffic information service provider. The service provider generates messages according to a standard TMC protocol using standardised event and location code lists, which is then sent to the appropriate FM radio broadcaster for transmission as an RDS (Radio Data System) signal within normal FM radio programmes.

The signal is ultimately delivered to a vehicle via a standard radio antenna. A full set of pre-defined messages is stored within the user's receiver, which then decodes the received message code in the driver's selected language and based on his or her needs (location, etc). In addition, new types of delivery mechanisms are emerging, including Internet, digital radio, paging and mobile phone networks.

In continental Europe, the data provided via the RDS-TMC system is broadcast over public radio networks, and is therefore free. In the UK, however, there are two commercial service providers who broadcast this data, ITIS and TrafficMaster.

Trafficmaster works with commercial radio stations, including GCap Media Plc and Chrysalis, to transmit its data via 88 separate radio transmitters across Great Britain.

More information about this service can be found at hap://www.trafficmaster.co.ulcJpage.cfm?key=pjMC The Trafficmaster system uses an established network of over 7,500 roadside sensors, which monitor traffic flow 24 hours a day, 365 days a year to collect traffic data, such as traffic flow rates. Traffic information is updated every four minutes.

ITIS, have a national licence, which allows them to broadcast data over the national FM radio network run by Classic FM. More information about this service can be found at www.itisholdings.com/itmc.asp. The ITIS system uses a fleet of around 1600 "floating" probes which are mounted on vehicles to monitor traffic flow rates and other traffic conditions. The ITIS system also incorporates police and journalistic data into its system in order to compile its traffic information service.

Conventionally RDS-TMC enabled receivers tune to the strongest Traffic Message Channel signal. For example, the VDO navigation system as found in some BMWs.

However, the strongest FM signal being received by the tuner does not always represent the most appropriate traffic information available. For example, close to country borders the strongest TMC signal may actually be from a neighbouring country. If the tuner is programmed to select the strongest signal available, then, in this example, the vehicle user may not receive useful traffic data.

It is also noted that some systems allow the user to manually select a TMC service provider from a list on the vehicle display. The problem with such systems is that the user rarely knows which service offers the most useful traffic data.

It is an object of the present invention to provide a traffic navigation system that is capable of overcoming or mitigating the above mentioned problems with prior art systems.

According to a first aspect of the invention, there is provided a navigation system comprising inputs for receiving data representing traffic information from a number of service providers; a processor arranged to select traffic information from one of the service providers based on a priority list; outputs for outputting traffic data derived from the chosen service provider to a user.

The present invention provides a navigation system that receives traffic information from a number of service providers and which can select a service provider based on a priority list that ranks the service providers.

Preferably, the priority list ranks the service providers on the basis of the quality of the service that they offer. Various factors can be used to rank the various services.

For example, the services can be ranked on the quality of the content that they offer and/or on their geographical coverage.

Preferably, the navigation system receives the traffic information via a Radio Data System-Traffic Message Channel broadcast. Alternatively, the navigation system can receive data from a Digital radio broadcast (DAB), a TPEG (Transport Protocol Experts Group) broadcast or via a GPRS based communications network.

A navigation system according to an embodiment of the present invention is able to differentiate and select a traffic broadcast on the basis of the quality of the service transmitted as opposed to selecting the strongest signal available, as is the case with

prior art systems.

Preferably, the processor is arranged to select the highest ranked service available.

However, conveniently, the processor may switch to a lower ranked service in the event that the signal strength of the highest ranked service provider falls below a certain threshold value. In this case, the processor may be arranged to revert back to the highest ranked service provider as soon as the signal strength rises above the threshold value.

Conveniently, the navigation system stores priority lists for different geographical regions (e.g. on a country, region or city level) thereby allowing the best traffic service to be selected based on the user's current location.

Conveniently, the navigation system comprises a navigation unit, which stores the priority list, and a radio tuner. The radio tuner is preferably a dedicated traffic navigation tuner and is separate to a second, "music" tuner such that normal operation of the radio is not affected.

Preferably, the navigation unit transmits a portion of the priority list, relevant to the navigation system's current location, to the tuner to allow the tuner to select and tune into the most appropriate traffic information service provider.

Conveniently, the priority list within the navigation system can be updated via a software release on a CD or DVD.

Ranking of service providers will be undertaken manually based on the considerations discussed above. The results of the manual ranking determine the form of the priority list that is loaded/hard-coded into the navigation system.

Preferably, the navigation system outputs traffic data based on the traffic information received from the selected service provider to a suitable output device.

Traffic data may be displayed visually (e.g. on a map, diagrammatically or as text based instructions) or may be communicated audibly.

According to a second aspect of the present invention there is provided a method of receiving traffic information comprising: receiving data representing traffic information from a number of service providers; selecting traffic information from one of the service providers based on a priority list and outputting traffic data derived from the chosen service provider to a user.

According to a third aspect of the present invention there is provided a data carrier comprising a computer program to implement the method of the third aspect of the present invention.

The invention extends to a vehicle comprising a navigation system according to the first aspect of the invention.

Brief description of drawings

The present invention will now be described, by way of example only, with reference to the following figures in which: Figure 1 illustrates a navigation system in accordance with an embodiment of the present invention; Figure 2 shows the traffic message channel table structure as stored in the tuner depicted in Figure 1; Figure 3 shows the traffic message channel table structure as stored in the navigation unit depicted in Figure 1; Figure 4 is a flow chart showing the mode of operation of a navigation unit operating according to an embodiment of the present invention; and Figures 5a, 5b and 5c show various output devices that may be used with a navigation system according to an embodiment of the present invention.

Detailed description of the preferred embodiments of the invention Turning to Figure 1, a navigation system according to an embodiment of the invention is shown generally at 10. The navigation system 10 comprises a navigation unit 12 which is in communication with a radio tuner 14. The radio tuner is connected to an antenna 16 which receives Radio Data System FM radio signals.

The RDS-FM signals include traffic information broadcast on the traffic message channel service from a number of service providers. Traffic data is output by the navigation system 10 as traffic signal 15 to a suitable display or output device (such as a display screen not shown in Figure 1).

A service priority list 18 is stored/hard-coded within the navigation unit 12. The list 18 contains details of various traffic message channel service providers which have been ranked on the basis of service quality.

The priority list 18 may be loaded onto the navigation unit 12 by means of a data carrier such as a CD-ROM or DVD 20. The priority list may also be updated by means of the CD 20.

The priority list 18 comprises a table of TMC services that are ranked by service quality. Ranking of services can take a number of factors into account. For example, commercial service providers often broadcast better quality of data than free to air services. Commercial service providers may therefore be ranked more highly than free-to-air service providers on the priority list 18.

The location of the navigation system may also affect the service quality. For example, service providers may have different geographical areas of coverage, i.e. they may return better traffic data in certain areas. The priority list may therefore rank a service provider according to location. The navigation system will then be able to select the service provider with the best local coverage. Location data may be derived from a positioning system such as GPS (or an equivalent) or alternatively from the radio broadcast that the tuner is receiving.

Geographical ranking may be on a country, region or city wide basis.

The tuner 14 comprises a list 22 which corresponds to a copy of part of the priority list 18 that is held in the navigation unit 12. The part of the priority list 18 that is sent from the navigation unit 12 to the tuner 14 is selected on the basis of the current location of the navigation system.

In use, the tuner compares the services it can receive via the antenna 16 against the ranked list 22 and tunes to the highest ranked service. Since the list rankings are based on service quality the service selected by the tuner may not necessarily be the service with the strongest signal strength.

Although the navigation system according to the present invention selects travel service providers on the basis of the service quality as opposed to the strongest available signal, it is noted that if the signal strength of the selected service falls below a certain threshold, the tuner 14 will tune to the next highest ranked service until such time as either the first selected service becomes available again or the signal strength of the second selected service falls below a threshold.

Figure 2 shows an example of the ranking list 22 stored within the tuner 14. The list 22 shown in Figure 2 is in the form of a table 30 comprising five columns.

The first column of table 30 (labelled 32 in Figure 2) details the ranking of the available service providers. In the table of Figure 2, there are three rows indicating that three service providers are available. The service providers have been ranked by quality of service where 1=best available service and 3=the lowest ranked service provider.

Traffic Message Channel broadcasts are identified in a standardised manner, i.e. they essentially have an identifying "fingerprint". Each TMC service/broadcast in Europe has a unique fingerprint that is made up of 3 individual items: (i) a country code, "CC" (Column 34 in the table of Figure 2), which details the originating country of the broadcast; (ii) a code, "LTN", that identifies and characterises the road network that is covered (Column 36 in the table of Figure 2), and; (iii) a service identification number, "SID" (Column 38 in the table of Figure 2), which is the unique ID of the service provider/broadcaster.

"LTN" stands for Location Table Number and is a two digit code that identifies the road network database that is being used by the service provider. This database relates to points on the road network and includes longitude and latitude co-ordinates. More than one Location Table may be in use within any one country. For example, in the UK a first Table may list the road network by roads, e.g. M25 motorway, Ml motorway. A second Location Table may detail points or nodes on each road, e.g. M25 motorway Junction 2, M25 motorway junction 4.

The "CC, LTN, SID" fingerprint is a standard way of identifying TMC broadcasts. It will be appreciated however that other methods of identifying and distinguishing between different service providers could be employed within the scope of the present invention.

The final column 40 in the table of Figure 2 is labelled "P1". A P1' code is a Program Identifier code and each RDS radio station will have a unique ID. If a PT of a station is known by the tuner 14, the tuner 14 is able to lock to the station and follow it regardless of how many frequencies are used to transmit it.

The table 30 held in the tuner 14 is based on the vehicle's current location. Different service considerations may apply in different geographical areas and so a more complete priority list 18 is hard-coded into the navigation unit 12.

Figure 3 shows the priority list 18 that is stored in the navigation unit 12. This list 18 comprises the service ranking for all geographical regions that the system covers and as such can be termed the "complete" priority list. It is noted that table 42 is similar to table 30. However, table 42 covers two geographical regions (Region A and Region B), labelled as columns 44 and 46.

Within each column 44, 46 a number of TMC service providers are characterised with respect to the CC, LTN, SID identification scheme described above. The service providers in each region are ranked (from "1" to "3") as before by service quality.

It is noted that the service providers in Region A may not be the same as the service providers in Region B. It is further noted that even if the service providers are the same in each Region then the priority ranking may not be the same.

The priority list as contained in table 42 may rank service providers on a country wide, region wide (e.g. Southern England), or city wide (e.g. London) basis. As the navigation unit 12 detects that the vehicle has moved from one geographical region to another the ranking list appropriate to that region can be sent to the tuner to allow the best service provider to be selected.

It is noted that the navigation system may derive location information from the RDS broadcast or from other means, e.g. a global positioning system device.

Figure 4 shows the mode of operation of a tuner 14 within a navigation system 10 according to an embodiment of the present invention.

In Step 50, the vehicle ignition is switched on and the radio system and tuner 14 are supplied with power.

In Step 52, the tuner 14 checks whether the priority table 22 is populated with priority, country code, location table and service ID data.

If the table 22 is not populated with data then the tuner 14 moves to step 54 in which it requests priority table data from the navigation unit 12.

In Step 56, the tuner 14 receives the priority table data appropriate to the vehicle's current location from the navigation unit 12 (i.e. it receives the appropriate section of the priority list 18 from the navigation unit 12) and populates the service table 22 accordingly. The tuner then cycles round to Step 52 again.

Once the priority table 22 is populated with data then the tuner moves from Step 56 to Step 58 in which it checks whether the TMC service provider table 22 is populated with program identifier (P1) codes.

If the table 22 is not populated with P1 codes then the tuner 14 moves to Step 60 in which it scans FM broadcasts received by the antenna 16 for PT information. This scanning step may take upto ten seconds per radio station to complete.

s The tuner then moves to Step 62 in which the P1 codes derived in the scanning Step are added to the TMC service provider table 22. The tuner then cycles back to Step 52 again.

Once the TMC service provider table 22 has been populated with priority data and PT codes then the tuner 14 moves to Step 64 in which it selects a service provider to tune to based on the priority ranking in the table 22.

As noted above the service providers are ranked, amongst other factors, according to quality of content and geographical coverage.

The navigation unit 12 holds a complete TMC service table 18 which details service rankings for different geographical regions. In the event that the vehicle moves into a new region then the appropriate service listing for that region can be sent to the tuner.

The tuner 14 may periodically check for alternative available TMC services in Step 66.

Figures 5a to 5c depict various display means that can be used to display the traffic data received in the traffic signal 15. In Figure 5a, the traffic data is displayed on a map of the local region (a "full map" representation). In Figure Sb, the traffic data is displayed as a series of traffic directions (a "turn by turn" representation). In Figure 5c, traffic data is displayed as a textual message (a "traffic only" representation).

Although the representations depicted in Figures 5a, 5b and 5c relate to visual display devices it is noted that traffic data may also be communicated via a speech announcement (either via a recorded message or a text-to-speech synthesis system).

It will be understood that the embodiments described above are given by way of example only and are not intended to limit the invention, the scope of which is defined in the appended claims. It will also be understood that the embodiments described may be used individually or in combination.

The preceding description of preferred embodiments requires that traffic information is input into the navigation system from an RDS-TMC radio broadcast. However it is possible to deduce traffic information by other means, such as from a TPEG (Transport Protocol Experts Group) broadcast, from a Digital Audio Broadcast (DAB) or from a GPRS message over a mobile phone network. Any such means of data input is contemplated within the broad inventive concept.

Similarly, whilst it is preferred to use a navigation system comprising a navigation unit and radio tuner as described above, this is not essential to the invention in its broadest sense. For example, the navigation unit and tuner may be a single integrated unit or the tuner may be replaced by a mobile phone receiver.

Claims

Claims 1. A navigation system comprising inputs for receiving data

representing traffic information from a number of service providers; a processor arranged to select traffic information from one of the service providers based on a priority list; outputs for outputting traffic data derived from the chosen service provider to a user.

2. A navigation system as claimed in Claim 1, wherein the priority list ranks service providers based on the quality of traffic information.

3. A navigation system as claimed in Claim 1 or 2, wherein the priority list ranks service providers based on geographical coverage.

4. A navigation system as claimed in any preceding Claim, wherein data is received via a Radio Data Service-Traffic Message Channel broadcast. 2c2

Amendments to the claims have been filed as follows Claims 1. A navigation system comprising: inputs for receiving data representing traffic information from a number of service providers; a processor arranged to select traffic information from one of the service providers based on a priority list; and outputs for outputting traffic data derived from the chosen service provider to a user.

2. A navigation system as claimed in Claim 1, wherein the priority list ranks service providers based on the quality of traffic information.

3. A navigation system as claimed in Claim 1 or 2, wherein the priority list ranks service providers based on geographical coverage.

4. A navigation system as claimed in any preceding Claim, wherein data is received via a Radio Data Service-Traffic Message Channel broadcast.

5. A method of operating a navigation system comprising the steps of: receiving data representing traffic information from a number of service providers; selecting traffic information from one of the service providers based on a priority list and outputting traffic data derived from the chosen service provider to a user.