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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
3/23/1999