GNGTS 2013 - Atti del 32° Convegno Nazionale

(configuration 2). During all measurements a regular wind with moderate speed of 5.5 m/s blew. The displacement spectra are obtained over the whole recorded ten minutes signal. A band-pass filter (0.3Hz-10Hz) was applied to reduce the presence of disturbances linked to atmospheric effects and to vibration of the sensor itself. The influence of the first effect is prevalent on the measured phases and, as a consequence, on the estimated displacements with long period (0.1-0.2Hz). Another effect is caused by the vibration of the measurement tool. Luzi et al. (2012) observe that the measured resonant frequency of the system ranges within Fig. 2 – One minute record acquired with the second configuration: LOS displacement retrieved from radar data as a function of the time. The time histories refer to two range-bins selected from the radar power profile and correspond to different heights of the tower. Fig. 3 – a) Sinusoidal trend of the displacement record obtained for the 50 th range-bin (30 metres height). b) Frequency analysis of the same time-history. a b 104 GNGTS 2013 S essione 3.2