Conditions of receiving RDS – TMC
The RDS-TMC service transmits traffic information about THE MOST IMPORTANT INCIDENTS that entirely or substantially limit the road traffic. The priority is given to high traffic density roads, i.e. incidents on motorways, expressways, and higher class roads.
In order to achieve a reliable reception of traffic information by a navigation device, IT IS NECESSARY TO HAVE:
- maps containing so-called location code tables for RDS-TMC, (the location code tables for the Czech Republic must be as current as possible, each new version covers a larger part of the road network),
- a navigation device, firmly attached to a holder with an aerial,
- an aerial positioned to provide the best possible FM broadcast reception (the aerials of some devices are not of very high quality and have lower gain, which may be adversely affected also by metallized windshields, hidden device location, etc.),
- the device set up to receive a specific service (JSDI-CRO on ČRo 3).
If these conditions are met, the device should receive and display current traffic information in a general view or for the selected route (the specific display differs according to the navigation device type).
Examples from abroad
Why an incident is not displayed correctly by the device
- the FM signal is not strong enough for the navigation, and thus it could not receive the current traffic information; the correct position of the aerial is crucial,
- some navigation devices are only capable of displaying certain traffic information types of the total number of almost 2000 items,
- some devices do not display information from great distances from the current position of the vehicle,
- an incident may be displayed in a different place than it really is; this is caused by the inaccuracy of the location code tables, the location accuracy depends on the coverage of the network by the location code tables,
- the given road is not included in the location code tables of the maps currently used by the device (the location code tables contain especially main roads, their coverage is gradually improving) and the given incident cannot be displayed,
- the incident has not been reported to the NTIC yet, or is currently being processed and published (the cycle of updating the information in the device may take several minutes - the declared capacity is about 300 messages within 15 minutes and depends on the size of the messages and their repetition frequency), in such case, please report the incident to the free drivers' line of the Czech Road and Motorway Directorate as traffic reporters or use the "Report Incident" section of this web,
- the information is displayed by the navigation, however, the road is passable again and the traffic has been restored. In such case, the National Traffic Information Centre has not been informed of the end of the incident; please report the situation to the free drivers' line of the Czech Road and Motorway Directorate as traffic reporters or use the "Report Incident" section of this web.
You can ask questions concerning the RDS-TMC service broadcast within the Integrated Traffic Information System for the Czech Republic using the section "Write to us".