wiki:ShShift
Last modified 15 years ago Last modified on 05/30/2008 12:19:53 PM

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shift traces in time

command: SHIFT [<trc-list> <time> [<p1> <p2> ... <pN>]]

Shifts traces by <time> seconds if <trc-list> and <time> are passed. If no parameters are passed, the graphic cursor appears and one trace can be shifted selecting the trace twice at different times. The trace is then shifted by the difference of the two time picks.

If <time> is one of the following keywords a special shift is applied to all traces of <trc-list>.

  • ps_delay
    Traces are shifted by the travel time difference of P and converted S, where the S conversion is generated at a depth of <p1> km. If <p2> is the string "slowness" the required slowness value is retrieved from the "slowness" info entry on each trace.
  • red_time:
    Reduced time display. Traces are shifted by a reduction velocity of <p1>. Each trace distance is retrieved from the "distance" info entry.
  • time_al
    Aligns traces in absolute time, that means the computed time delays account for differences in the start times ("start" info entry) of the traces.
  • sd_delay
    not documented :(

All computed time shifts are added to already existing delays of the traces, i.e. they are relative time shifts. If the same shift command is applied twice, the time shift is also twice as large.

parameters

  • <trc-list> parameter type: trace list
    List of traces to be shifted by <time> seconds. If omitted one trace can be shifted by graphic cursor (see above).
  • <time> parameter type: real
    Time in seconds the traces in <trc-list> are to be shifted. Only valid if <trc-list> is specified. <time> can also be a keyword determining a shifting algorithm for the traces in <trc-list>. A list of valid keywords if given above.

qualifiers

  • /nomark
    Only valid if <trc-list> is omitted. The selected time points at the shift trace are not marked.

examples

shift
shift one trace by graphic cursor
shift all -10
shifts all traces by 10 sec to the left
shift all ps_delay 640 slowness
shift all traces to align a conversion depth coming from 640 km depth