VHF-radars have been successfully used for remote sensing of the lower and middle atmosphere. The received radar-echoes are digitized and these raw data are processes in several sequential steps. By digitally filtering the raw data which is equivalent to a compression or a coherent integration, the amount of data is reduced and at the same time the signal-to-noise ratio is increased. After this preintegration procedure the compressed data are calibrated and digitally corrected. Using correlation methods the spatial and temporal variations of the echo-power as well as the velocity of the reflecting or backscattering medium are determined. Results of measurements using the Jicamarca radar facility and the SOUSY-VHF-radar are presented.