The use of GPS/GNSS for road charging schemes is one area currently being considered by many government and transport authorities worldwide in support of strategies to reduce traffic volumes and congestion. However, before any decisions can be taken as to which system should be implemented, each system needs to be investigated and compared with strengths and weaknesses of each evaluated and understood.

In the case of a GNSS device being used as an in-vehicle unit to support a road charging application, a variety of issues will be relevant including some or all of the following:

• How to select suitable receivers for on-board units
• How to ensure that receivers track accurately and remain true to the road or area that the vehicle is on
• How to deal with potential interference, whether intentional or unintentional
• The need to check that the road tolling system is operating as expected over a range of test routes and conditions. This could include moving between jurisdictions, routes of varying length and with complex turns and manoeuvres.
• The design needs to meet applicable regulatory requirements to ensure the integrity of the system

Spirent is working closely with system and application developers in the GNSS transport based application area to provide a range of assistance in this area, including:

• Laboratory based simulation with realistic routes that can be generated from either NMEA data, Google maps or customer’s own motion files
• Test scenarios that model the most challenging parallel roads and crossing road cases to quantify the system performance
• The ability to replicate a known route in the laboratory precisely, and using a number of on-board units from different vendors, and different revisions of unit from the same vendor, to ensure that the performance remains valid and within specification

You can rely on simulation to provide realistic and trustworthy results; simulators can reduce the need for drive testing and add the benefits of controlled, repeatable testing, taking out the uncertainty in your testing.

For further information please contact gnss-solutions@spirent.com.

SPIRENT'S VALUE FOR GNSS BASE ROAD TOLLING TESTING

GNSS satellite navigation is becoming an essential element of many transport projects, from in-vehicle navigation through to road tolling and telematics applications. Many projects in this sector are complex with safety and commercial objectives to satisfy, with few standard guides to performance definition or test approaches.

Spirent has wide experience of helping companies in this sector understand their test issues and the best approach to testing. Spirent can help, click on the links to find out more.