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The spec Command

The spec command will create a new plot consisting of the Fourier transforms of the vectors given on the command line.

spec start_freq stop_freq step_freq vector [...]
This is based on a SPICE3 spec command by Anthony Parker of Macquarie University in Sydney Australia, which is available as part of the patch set from
http://www.elec.mq.edu.au/cnerf/spice/spice.html.

The command will create a new plot consisting of the Fourier transforms of the vectors given on the command line. Each vector given should be a transient analysis result, i.e., have time as a scale, and each should have the same time scale. The Fourier transform will be computed using the frequency parameters given, and will use a window function as given with the specwindow variable.

The following variables control operation of the spec command. Each can be set with the set command, or equivalently from the Fourier tab of the Commands tool.

spectrace
This enables messages to be printed during Fourier analysis with the spec command, for debugging purposes.

specwindow
This variable is set to one of the following strings, which will determine the type of windowing used for the Fourier transform in the spec command. If not set, the default is hanning.

bartlet Bartlet (triangle) window
blackman Blackman order 2 window
cosine Hanning (cosine) window
gaussian Gaussian window
hamming Hamming window
hanning Hanning (cosine) window
none No windowing
rectangular Rectangular window
triangle Bartlet (triangle) window

specwindoworder
This can be set to an integer in the range 2-8. This sets the order when the gaussian window is used in the spec command. If not set, order 2 is used.


next up previous contents index
Next: The undefine Command Up: Data Manipulation Commands Previous: The settype Command   Contents   Index
Stephen R. Whiteley 2017-02-22