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== Slowness-wavenumber analysis on array traces ==
'''command''': FK [] [] [] [] []
Perform FK analysis on array traces, determine slowness and azimuth of incoming plane wave. Based on obspy routine "array_processing".
=== parameters ===
* ''parameter type: trace list''[[br]]
List of input traces for FK algorithm.
* ''parameter type: float''[[br]]
Start time of time window in seconds read from time axis.
* ''parameter type: float''[[br]]
End time of time window in seconds read from time axis.
* ''parameter type: float''[[br]]
Lower bound of frequency window for FK in Hz.
* ''parameter type: float''[[br]]
Upper bound of frequency window for FK in Hz.
* ''parameter type: float''[[br]]
Upper bound of slowness in s/deg in x and y direction.
* ''parameter type: output variable''[[br]]
Name of output variable for slowness result in s/deg.
* ''parameter type: output variable''[[br]]
Name of output variable for azimuth result.
=== qualifiers ===
* /winlen=[[br]]
Window length in s for segments put into FK algorithm. Default: - , i.e. only one time step is computed.
* /winfrac=[[br]]
Fraction of window used as step size (see description of obspy array_processing routine). Default 0.05.
* /slostep=[[br]]
Slowness step size, determines resolution of output matrix, default /100.
* /scatter=[[br]]
Output filename for scatter plot. The scatter plot contains the results of each time step.
* /polar=[[br]]
Output filename for polar plot. The polar plot contains a histogram of the results of all time steps.
* /slownessmap=[[br]]
Output filename for slowness map. The slowness map contains the slowness matrix of a single time step.
* /kmunits[[br]]
Input numbers and plot scalings are given in s/km instead of s/deg.
=== example ===
`fk 17-51 53. 69. 0.4 3.0 15.0 &slo &az /slownessmap=slmap.png`::
Compute slowness and azimuth for signals between seconds 53. and 69. for traces 17 to 51 in a frequency range between 0.4 and 3 Hz and a maximum slowness of 15 s/deg. The results are copied into variables "slo" and "az". The slownessmap of this single time step is produced in file "slmap.png".