pdf: http://www.ipt.ntnu.no/~stanko/files/Courses/TPG4230/2020/Lecture_notes/20200320.pdf
files: http://www.ipt.ntnu.no/~stanko/files/Courses/TPG4230/2020/Class_files/20200320/elevation_vs_time.txt
video: http://www.ipt.ntnu.no/~stanko/files/Courses/TPG4230/2020/Videos/20200320_2_wave_data_analysis_with_FFT.mp4