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jvs:fscan:manual:chapter2:expression:bandpass [2011/09/18 19:28] voyvodic |
jvs:fscan:manual:chapter2:expression:bandpass [2011/09/20 02:56] voyvodic |
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**fScan Reference Manual, Chapter 2 (CmdLineOptions: | **fScan Reference Manual, Chapter 2 (CmdLineOptions: | ||
===== Bandpass -- Apply a bandpass frequency filter to input data ===== | ===== Bandpass -- Apply a bandpass frequency filter to input data ===== | ||
- | | + | |
- | The BANDPASS function will filter out frequencies | + | The BANDPASS function will filter out both low and high frequency signals from a time series data set. Usually, |
- | If MINFREQ | + | For convenience, |
- | The FLAG argument can be used to select | + | Note: For temporal |
+ | SCALEFACT is a scaling factor; FFT output intensity values will be divided by SCALEFACT. Default SCALEFACT is 1000. | ||
+ | |||
+ | The FLAG argument can be used to select filtering options.\\ | ||
FLAG: | FLAG: | ||
- | * 1 - frequencies are in time axis units (i.e. TR' | + | * 1 - frequencies are in Hertz (default: frequencies are seconds) |
- | * 2 - 2-d spatial filtering (default is temporal filtering) | + | * 2 - 2-d spatial filtering |
- | * 4 - make output wordsize same as input (default: output is FLOAT32) | + | * 4 - frequencies are number of cycles across time course (default: seconds or Hertz) |
+ | * 8 - make output wordsize same as input (default: output is FLOAT32) | ||
+ | * 16 - filter out 0 frequency (default: 0 freq mean signal is preserved) | ||
+ | * 32 - no filtering (test FFT -> reverse FFT) | ||
+ | |||
+ | Example: | ||
+ | < | ||
+ | -expr bandpass 0 30 3 ; filter out frequencies below 30s (0.033 Hz) and above 3s (0.33 Hz) | ||
+ | -expr bandpass 1 0.033 0.33 ; same as above, specified in Hertz | ||
+ | -expr bandpass 4 10 100 ; filter out frequencies below 10 cycles and above 100 cycles | ||
+ | -expr bandpass 0 10 40 ; filter out frequencies between 10s (0.1 Hz) and 40s (0.025 Hz) | ||
+ | </ | ||
**See Also:**\\ | **See Also:**\\ |