Observing the normal oscillations and the behaviours of high-engineering structures has become almost a necessity in terms of construction security and human health. For this purpose, an real-time kinematic GPS (NovAtel 400) and a tilt sensor (Leica Nivel20) were installed in a TV tower (220m high) located in Istanbul, Turkey. The observation serials were recorded over a period of 9days. All data-sets in X and Y directions were examined in the time domain and were analyzed using FFTEuro. The dominant frequency values (significant frequencies) were determined by comparing at the high- and low-frequency values. These dominant frequencies showed that the tower made 4- and 6-second short-period oscillations and 24- and 12-hour long-period oscillations. All the observation signals were re-created by the significant low-frequency values using the inverse Fourier transform. Thus, the motion model of the tower was determined over 9days. In this study, the 24-hour and 12-hour periodic oscillations were defined that represent the behaviour of the tower in relation to the effect of the sun's radiation and the temperature changes.