4.50 sddsfdfilter

• description: sddsfdfilter performs frequency-domain filtering of data columns using Fourier transforms. It supports thresholding, highpass, lowpass, notch, bandpass, and user-defined filters. Multiple filters may be cascaded or applied in parallel, and the program can create new or difference columns in the output.
• examples:
      sddsfdfilter data.sdds filtered.sdds -columns=t,value -lowpass=start=1,end=10  
      sddsfdfilter data.sdds filtered.sdds -columns=t,value \  
        -notch=center=60,flatWidth=2,fullWidth=5  
      

• synopsis:
      sddsfdfilter [-pipe[=input][,output]] [inputfile] [outputfile]  
                   [-columns=indep-variable[,depen-quantity[,depen-quantity...]]]  
                   [-exclude=depen-quantity[,depen-quantity]]  
                   [-clipFrequencies=[high=number][,low=number]]  
                   [-threshold=level=value[,fractional][,start=freq][,end=freq]]  
                   [-highpass=start=freq,end=freq]  
                   [-lowpass=start=freq,end=freq]  
                   [-notch=center=center,flatWidth=width1,fullWidth=width2]  
                   [-bandpass=center=center,flatWidth=width1,fullWidth=width2]  
                   [-filterFile=filename=filename,frequency=columnName,  
                               {real=columnName,imaginary=columnName |  
                                magnitude=columnName}]  
                   [-cascade] [-newColumns] [-differenceColumns]  
      

• files: The optional inputfile is an existing SDDS file to filter. If omitted, the program reads from standard input when -pipe=input is given. The outputfile receives the filtered data, or standard output is used when -pipe=output is specified.
• switches:
  • -pipe[=input][,output] — The standard SDDS Toolkit pipe option.
  • -columns=indepVariable[,depenQuantity][,depenQuantity...] — Gives the name of the independent variable (typically time). If no depenQuantity qualifiers are given, all numerical columns are filtered; otherwise, only the named columns are processed.
  • -exclude=depenQuantity[,depenQuantity] — Specifies columns to exclude from filtering, modifying selections from -columns.
  • -clipFrequencies[=low=frequency][,high=frequency] — Clips frequencies below the low value and/or above the high value; clipped components are set to zero.
  • -threshold=level=value[,fractional][,start=freq][,end=freq] — Suppress components below a threshold. With fractional, the level is a fraction of the largest component. start and end restrict the frequency range.
  • -highpass=start=freq,end=freq — Apply a highpass filter.
  • -lowpass=start=freq,end=freq — Apply a lowpass filter.
  • -notch=center=center,flatWidth=width1,fullWidth=width2 — Apply a notch filter centered on a frequency.
  • -bandpass=center=center,flatWidth=width1,fullWidth=width2 — Apply a bandpass filter centered on a frequency.
  • -filterFile=filename=filename,frequency=columnName, {real=columnName,imaginary=columnName | magnitude=columnName} — Specifies a filter via an SDDS file of attenuation values. The column named with the frequency qualifier gives the frequency values. Components outside the provided range are unaffected.
  • -cascade — Cascade multiple filter definitions.
  • -newColumns — Create new columns containing filtered results.
  • -differenceColumns — Create columns containing differences between original and filtered data.
• see also:
  • sddsdigfilter()
  • sddssmooth()
• author: M. Borland, ANL/APS.