30TH INTERNATIONAL COSMIC RAY CONFERENCE Trigger Strategy for Radio Detection of Atmospheric Air Showers with LOPES

In the framework of LOPES (LOFAR PrototypE Station), a Self-Triggered Array of Radio detectors (STAR) is developed. The challenge of LOPES is to provide an independent self-trigger on radio emission of extensive air showers with primary energies above 5 · 10 eV. Measurements are done with an external trigger and self-trigger in radio loud and quiet areas. Based on these data the self-trigger is optimised and higher level triggers are developed, as well as algorithms for reconstruction of shower observables. The methods and first results from LOPES are described.