FFT power spectrum
command: FFT <trc-list> <lo-time> <hi-time> <k> [<m>]
Computes power spectrum of input traces (given by <trc-list>) using the FFT. For the computation only the time window between <lo-time> and <hi-time> on the input traces is used. <k> specifies the number of partitions on the input traces. The resulting power spectrum is the sum of the power spectra of the separate partitions. <m> is the length of a partition in samples. <m> must be a power of 2. If not specified it is determined automatically as large as possible.
parameters
- <trc-list> parameter type: trace list
List of traces to compute power spectum.
- <lo-time>, <hi-time> parameter type: real
Time window on input traces (sec.). If not entered the current display window is used.
- <k> parameter type: integer
Number of partintions on each trace
- <m> parameter type: integer
Length of each partition in samples. Must be a power of 2. If not entered it is determined automatically as large as possible.
qualifiers
- /overlap
If specified the partitions overlap by 50%.
example
- fft/overlap 1-3 0. 50. 3
- computes power spectrum of traces 1-3 within a time window from 0. to 50. sec. Number of partitions is three. The partitions are overlapping. <m> is determined automatically.
- fft 1;;;3 512
- computes power spectrum of trace 1 within the current display window.
