IRIS DMC MUSTANG metrics Web Service Documentation

max_gap Maximum daily data gap

Summary

Indicates the size in seconds of the largest gap encountered within a 24-hour window.

Uses

Data gaps can indicate problems with data transmission configuration or performance, power cycling or other equipment down time, or data loss after transmission. The metric can also be used to cull data that is not continuous enough for certain research applications.

Data Analyzed

Traces – one N.S.L.C (Network.Station.Location.Channel) per measurement
Window – 24 hours starting at 00:00:00 UTC
Data SourceIRIS miniSEED archive or IRIS PH5 archive

SEED Channel Types – ?H?, ?L?, ?N?, ?G?, ?P?, VM? | High Gain, Low Gain, Accelerometer, Gravimeter, Geophone, Mass Channels

Algorithm

  • Request 24 hours of data for a single Channel (N.S.L.C)
  • Request the data sample rate, defining a gap as larger than one sample interval.
  • Assume that missing data at the beginning of the day is a gap that begins at the day boundary and ends when the data begins.
  • Assume that missing data at the end of the day is a gap that begins after the last data sample and ends at the day boundary.
  • For x data segments returned,
    • Calculate the end time of each data segment:
      endtime(x) = starttime(x) + ( (num_samples(x) - 1) / sample_rate)
      
    • Calculate gap lengths between segments:
      gap(x) = starttime(x) - endtime(x-1) - (1 / sample_rate)
      
    • Find the maximum gap length for this day:
      max_gap(x) = max( (gap(x)>0), max_gap(x-1) )
      

Metric Values Returned

value – maximum daily gap length in seconds
target – the trace analyzed, labeled as N.S.L.C.Q (Network.Station.Location.Channel.Quality)
start – beginning of the data day requested (00:00:00 UTC)
end – end of the data day requested (truncated as 23:59:59 UTC)
lddate – date/time the measurement was made and loaded into the MUSTANG database (UTC)

Notes

Gap lengths currently are not measured across day boundaries. A gap crossing a day boundary is treated as two separate gaps for purposes of measuring maximum daily gap length.

Contact

See Also

Updated

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