Sat NAV TMC

**Leslie** · 9th July 2006, 11:39

Can someone tell me about TMC - collecting a 1.9CDTI Elite next week with the full sat nav kit and colour display - Facelift model - My old 2.2DTI Elite is in for a swap.

**DennisTheMenace** · 9th July 2006, 13:36

good ol cut and paste ........

The Traffic Message Channel (TMC) is a specific application of the FM Radio Data System (RDS) used for broadcasting real-time traffic and weather information. Data messages are received silently and decoded by a TMC-equipped car radio or navigation system, and delivered to the driver in a variety of ways. The most common of these is a TMC-enabled navigation system that can offer dynamic route guidance - alerting the driver of a problem on the planned route and calculating an alternative route to avoid the incident.

Benefits for users

* Updated traffic information, delivered in real time
* Instant knowledge of accidents, roadworks and traffic jams
* Filtered information only for the immediate route
* Information in user's own language
* High-quality digital transmission
* Europe-wide compatibility of receivers
* Free or low-cost services right across Europe

Instant information en route

TMC traffic information offers several advantages. First, it is received via a "silent" FM data channel, which means that users can listen to music or news broadcasts simultaneously with - and without interference from - TMC data transmissions. Second, messages arrive and are displayed immediately, so you don't need to wait for the scheduled traffic news bulletin, or to listen to a specific programme. Also, TMC services are continuous and presented directly to the driver, unlike occasional roadside information services such as variable message signs.

In the user's language

Thanks to TMC receiver technology, users can receive traffic information in their own language. The TMC unit, typically an in-car navigation system, decodes the received traffic information and presents it to the user. Whichever country the user is driving in, he or she can understand the local traffic situation immediately.

Across Europe

TMC traffic information systems conform to a global standard that has been adopted by traffic data gatherers, information service providers, broadcasters and vehicle/receiver manufacturers. TMC information is received via the normal FM radio antenna.

All TMC receivers use the same list of event codes, while the location database (typically on the navigation system map CD-ROM or DVD) contains a country-specific set of location codes for the strategic European road network.

TMC traffic data are already being broadcast in Austria, Belgium, Denmark, Finland, France, Germany, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland and the United Kingdom. Also planning services soon are the Czech Republic, Hungary, and Portugal.

How does it work?

Data related to traffic flows, incidents, weather etc. are gathered from traffic monitoring systems, emergency services, motorists' calls etc., and are collated at a central traffic information centre. They are then passed to the TMC traffic information service provider, who generates TMC messages according to the ALERT-C coding protocol.

What information is included in a TMC message? Standard TMC user messages provide five basic items of broadcast information:

* event description, details of the weather situation or traffic problem and its severity
* location, the area, highway segment or point location affected
* direction and extent, identifying the adjacent segments or point locations affected, and the direction of traffic affected
* duration, how long the problem is expected to last
* diversion advice, whether or not drivers are advised to find an alternative route.

The service provider sends the coded messages to the appropriate FM radio broadcaster for transmission as an RDS (Radio Data System) signal within normal FM radio transmissions. The TMC data are received by the vehicle radio and antenna, and decoded by a TMC decoder. This reconstructs the original message, using a database of event and location codes, which is presented to the driver as a visual or spoken message.

It takes typically about 30 seconds from the first report of a traffic incident to the traffic information centre until the same information is available in the vehicle.

The user can select the language used to present the traffic information by the TMC receiver, typically a navigation system or car radio. The user can also opt to filter messages, so that only those concerning the immediate route are selected.

New delivery channels are emerging that could carry TMC services, including digital radio (DAB), mobile Internet, paging and GSM/GPRS mobile phone networks.

**Leslie** · 9th July 2006, 14:35

Thanks - will see how it works next week

**MLC** · 9th July 2006, 20:25

Check which sat nav disc you've got. TMC doesn't work on my nov 04 car. Checked the disc and it's a 2003 one. Apparently it has to be 2005 or newer.

Someone will give the full (and correct

) details soon.