The CODALEMA experiment is based on an original approach of the detection of radio transients associated with extensive air showers induced by ultra high-energy cosmic rays. Since September 2006, CODALEMA has been under operation with a new setup at the Nançay Radio Observatory, France. We will present evidence for the radio detection of cosmic rays above 10^17 eV, based on an event-by-event analysis and we will discuss the radio characteristics of these showers.