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RESAMPLE

        ANALYSE\RESAMPLE Nx Xref Xval Xinc Unit [Shape] [Width] [/[NO]FFT]
        ANALYSE\RESAMPLE /LIKE GDFFile [/FFT]

    This  command  resamples a given spectrum on a specified X axis in given
    unit. The arguments are:
      Nx    the number of channels desired,
      Xref  the new reference channel,
      Xval  the value at the reference channel. Changing the reference  fre-
            quency  or velocity has non trivial effects on the axis. Use '='
            when possible (see below), else change the value with caution,
      Xinc  the new channel separation. In case of FREQUENCY resampling, the
            resolution  is expected to be given in the restf frame. However,
            RESAMPLE does not modify the current frame of the spectrum (i.e.
            the  Doppler  factor  is left unchanged), so the input frequency
            resolution will be corrected to the current frame.
      Unit  either VELOCITY or FREQUENCY to indicate the units used for Xval
            and Xinc.
      Shape (optional)  a  keyword for the frequency response of the synthe-
            sized channels (see subtopic for details). By default the  shape
            of  the  output  channels  is the same as the shape of the input
            channels.
      Width (optional) the width of the output  channels  in  units  of  the
            channel separation. The default (and minimum value) is 1.

    Using  an equal sign '=' for any of these arguments indicates to use the
    same value as before. Using a wildcard '*' will choose an automatic  de-
    fault:
      Nx    is set such as the last input and output channels are aligned,
      Xref  is set such as the first input and output channels are aligned,
      Xval  the reference frequency and velocity are left unchanged (same as
            =)
      Xinc  same as =
      Shape same as =
      Width same as =

    /NOFFT is the default behavior. In this case, the output spectrum  is  a
    subset  of  the original one if their axes are aligned to a given preci-
    sion. If not, the spectrum is resampled by direct interpolation. In this
    mode  the  exact channel separation requested will be used. The counter-
    part to this technique is that correlation is introduced  between  adja-
    cent  channels  and thus affects the noise intensity (e.g. it is divided
    by sqrt(2) if the axis is shifted by half a channel).

    The Width parameter is used to provide an oversampled output spectrum if
    needed.


Subsections

Gildas manager 2018-10-16