Three trends affecting the way automotive RF engineers test systems: Page 4 of 6

April 14, 2016 //By Franz-Josef Dahmen, Anritsu
Three trends affecting the way automotive RF engineers test systems
Today a car is far more than a means to move quickly and safely from A to B: it is a comprehensive living space in which we can be informed, entertained and productive just as effectively as when at home or in an office. All these electronic features have their specific needs and requirements for testing.
spectrum in the 5.9GHz range has been allocated to it in Europe, in line with similar allocations in the US. As soon as two or more cars or ITS stations are in range, they will connect automatically and set up an ad hoc network in which all ITS stations know the location, speed and direction of the surrounding stations, and will be able to share messages, warnings and information.

 

As the communication range of a WLAN connection is limited to a few hundred metres, every vehicle also acts as a router for message forwarding. The routing algorithm will be based on the position of the vehicles, and can handle rapid changes to the ad hoc network topology (see Figure 1).

 

The implementation of C2C wireless communications thus calls not only for robust RF performance, a physical layer function which can readily be verified with the use of an instrument such as a spectrum analyser – the MS2830A from Anritsu is a good example. The system designer must also implement a sophisticated test plan for verifying the protocol layer performance, to show that it can handle rapid changes in network topology without dropping packets or losing connections. As above, standard test specifications might not capture the full depth of testing required under the provisions of ISO 26262, and this looks set to demand a new approach to the design and implementation of test routines from automotive RF engineers.


Fig. 1: transfer rates, modulation schemes and coding rates specified in the IEEE 802.11p standard, for a 10MHz channel bandwidth

 

eCall: another safety-critical technology

The European Union’s eCall system, and the similar ERA-GLONASS (in Russia) combines mobile communications and satellite positioning to provide fast, reliable assistance to motorists in the event of an accident.

 

Both systems rely on satellite location data, the first on GPS, the latter on GLONASS. When in-vehicle sensors trigger events such as airbag deployment, eCall

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