wiki:ShBeam
Last modified 15 years ago Last modified on 04/29/2008 04:15:26 PM

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beam traces

command: BEAM <trc-list> <azimuth> <slowness>

Delays traces specified in <trc-list> to align seismic phases with the same azimuth and slowness. The computed delays are added to already existing delays of the traces unless the "/abs" qualifier is specified.

SH needs to know the station names where the traces in <trc-list> were recorded. If not all station names are given, an error occurs. SH uses a location file to look for the location of a station. If a station name is not listed in this file, an error occurs. In this case the unknown station must be inserted to the location file using the "FCT station" command. For each station latitude and longitude (in degrees) must be entered. SH uses this information to compute the relative distances between the stations. Therefore the location information must be accurate enough. For station arrays there can be specified an array-relative location (in km) and an array ID number. If all stations of <trc-list> belong to the same array (same array ID number), SH uses the array relative location to shift the traces rather than the latitude,longitude information. The "/noarray" qualifier forces seismic handler to use latitude,longitude information instead of using the relative positions (if specified).

parameters

  • <trc-list> parameter type: trace list
    List of traces to be beamed.
  • <azimuth> parameter type: real
    Azimuth of phase to be aligned given in degrees.
  • <slowness> parameter type: real
    Slowness of phase to be aligned given in sec/degree.

qualifiers

  • /noarray
    The stations are assumed to be no array even if array coordinates are given for all stations in the location file. If no array coordinates are given the qualifier has no effect.
  • /abs
    The delays computed are used as new delay values for each trace and are not added to already existing delays.

example

beam all 30.0 5.0
shift all traces to beam a phase of azimuth 30 degrees and slowness 5.0 sec/deg