How does GPS work?

TomTom Education

How does my TomTom device work?

More than just getting you from A-B

So now you know how your device calculates your exact whereabouts. But actually your TomTom device can use all this technology to enhance your journey in many other ways as well. A particularly good example of how your TomTom device uses smart technology to make itself even smarter is RDS-TMC ("Radio Data System-Traffic Message Channel").

This is a service that delivers real-time traffic information onto your navigation device. An RDS-TMC receiver (an accessory available for all TomTom devices) receives traffic data, decodes it and translates it into visual or audible 'traffic alerts’. Warning symbols appear on your screen, so you can see exactly where the problem is. And as the data is directly integrated into your device, you’re automatically offered an alternative route.

How does RDS-TMC work?
TMC traffic information systems conform to a global standard that’s been adopted by data gatherers, information providers, broadcasters, and vehicle and navigation makers.

So data related to traffic flows, incidents, weather etc. can be gathered from a variety of sources (traffic monitoring systems, emergency services, motorists' calls, etc), collated at a central information centre and passed on to a TMC information service provider.

TMC messages contain a considerable amount of information:

  • Identification: what’s causing the traffic problem and its seriousness
  • Location: the area, road or specific location affected
  • Direction: the traffic directions affected
  • Extent: how far the problem stretches back in each direction
  • Duration: how long the problem is expected to affect traffic flow
    And perhaps most useful:
  • Diversion advice: alternative routes to avoid the congestion

The service provider encodes the message and sends it to FM radio broadcasters, who transmit it as an RDS (Radio Data System) signal within normal FM radio transmissions. The TMC decoder inside your TomTom device then decodes the message and presents it as a visual or spoken message. There’s usually only about 30 seconds between the first report of an incident to the traffic information centre and your RDS TMC receiver getting the message.

I = First information on traffic situation

II = Central information centre: collecting all traffic info

III = TMC information service provider: encoding traffic info

IV = FM radio broadcasters: transmission RDS signal

V = TMC decoder: decoding RDS signal into visual and/or spoken message on your TomTom

These and many other extra services (TomTom PLUS services) are available either directly to your device or by downloading them yourself via the internet.
The later TomTom devices have many other great features. Like allowing you to play and control the music on your I-Pod or to run a slideshow of your favourite photos.

Bluetooth®, UMTS and GPRS
Bluetooth® enables your TomTom device to communicate with other electronic devices you own with Bluetooth technology, such as your mobile telephone. The communication travels via a frequency between the two devices. Making it possible, for example, to call handsfree or receive information sent to your mobile telephone, such as the latest traffic or weather updates.

To receive this information, your mobile needs a wireless connection such as GPRS (General Packet Radio Service) or UMTS (Universal Mobile Telecommunications System). Both technologies allow information to be sent and received via a mobile telephone network that charges by the amount of data sent, rather than by the length of time you’re connected.

As you can see, progress in the world of satellite navigation is fast and furious. Each new scientific or technological advance can often be converted into a practical improvement for navigation devices or navigation services. Making your TomTom device more clever every time.

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