Abstract
DEMETER is an ionospheric micro-satellite launched on a polar orbit at an altitude of 710 km. Its main scientific objectives are to study the ionospheric perturbations in relation with the seismic activity and the anthropic activity. Therefore, it allows a survey of the electromagnetic environment of the Earth. Its scientific payload allows to measure electromagnetic waves and plasma parameters in the ionosphere. After more than 18 months of operation, this paper will present on one hand observations of natural ELF/VLF waves, and on the other hand observations of man-made waves. Among the natural waves, DEMETER has shown that quasi-periodic emissions are frequently observed around the Earth. Specific harmonic emissions in relation with Electro Magnetic Ion Cyclotron waves are also observed in the ionosphere during intense magnetic storms. Concerning the man-made waves, DEMETER has registered emissions associated with the VLF ground-based transmitters and with the Power Line Harmonic Radiations.