VLF-1 is an antenna dedicated to the observation of Very Low Frequency signals. This antenna is located close to PB8.
According to IUT, the VLF radio band ranges from 3 to 30 KHz, which corresponds to myriametric wavelengths. This band is mainly used for radio navigation services: time signals broadcasting and military communications with submarines. These stations transmit signals at well know frequencies, most of them using a MSK (Minimum Shift Keying) modulation.
The electromagnetic activity in the myriametric band is also a consequence of various natural phenomena. For example, lightnings or solar flares can produce observable signals in this band. The study of these signals can be of real importance to anticipate impacts of these phenomena on human activities.
ORPB is running a VLF station. Our research activity is to find out some characteristics of the atmosphere and ionosphere given signals received from different terrestrial stations [note AG: préciser et reformuler avec l’avis de Patrick].
Practically, this VLF station covers the band 10 kHz – 80 kHz. It is made of a radio front-end (wire antenna, amplifier and filter), a digitalization device and a computer with a spectral analysis software.