| T O P I C R E V I E W |
| subash123 |
Posted - 01/26/2010 : 08:47:13 AM
I am using OriginPro 8.1 evaluation version in window XP operating system. I would like use the FFT for rainfall analysis. I would like to use FFT to know any periodicity in rainfall. please help me, how to use FFT and how to enter data set. For eg. I would like to know the cyclic shifting of maximum rainfall between July and August during 30 years period for a complete period of 120 years data set. |
| 1 L A T E S T R E P L I E S (Newest First) |
| easwar |
Posted - 01/26/2010 : 4:57:37 PM
Hi Subash,
In 8.1 try the following:
1> with a new workbook/sheet active, use single ascii import to import the file: \samples\signal processing\average sunspot.dat
2> select the 2nd col and make a line plot - this is year-by-year sunspot data
3> select the menu Analysis->Signal Processing->FFT and set what outputs you desire
4> look at amplitude/magnitude for example and you will see a peak at around 0.09 which corresponds to 1/11 so that is the 11-year cycle in sunspots
Under Analysis menu, in Pro, there is also Short-time Frequency analysis tool (STFT) which can do FFT over a sliding window in time.
If you have specific questions, please share your data with us so we could look at it further.
Easwar
OriginLab |
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