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Period analysis

Let us assume that table OBSERVP.tbl contains observations of a periodic phenomenon. The observations are stored in the DOUBLE PRECISION columns :TIME and :VALUE.


CREATE/GRAPHICS 		 ! Create graphics window 
SET/CONTEXT TSA ! Enable TSA package
NORMALIZE/TSA OBSERVP :VALUE ! Subtract mean
BAND/TSA OBSERVP ! Find suitable frequency band
SHOW/TSA ! Inspect corresponding settings
POWER/TSA OBSERVP POWERSPEC ! Compute power spectrum and
! spectral window
PLOT/ROW POWERSPEC ! Display power spectrum
PLOT/ROW POWERSPEC 2 ! Display spectral window
ORT/TSA ? AOVSPEC ? ? ? ! Compute multiharmonic spectrum
PLOT/ROW AOVSPEC ! Inspect results
POWER/TSA ? LINESPEC 20 .01 501 ! Compute detail of power spec.
PLOT/ROW LINESPEC
! Plot it
WIDTH/TSA LINESPEC ! Find parameters of
! the oscillation
SINEFIT/TSA OBSERVP CLNOBS 23 1 ! Remove one particular
! Fourier component
POWER/TSA CLNOBS POWCLN ! Inspect periodogram of data
              ! after removal of 1 oscillation



Petra Nass
1999-06-15