SAGE Facility MUSTANG metrics Web Service Documentation

This metric counts the times this clock quality flag is set from 0 (default) to 1 in the fixed section of the miniSEED header. A flag value of 1 indicates that the SEED timing quality has fallen below some datalogger-specific level. For some dataloggers, that level indicates that the GPS clock has not obtained a satellite lock since the system last powered up. It does not necessarily indicate that the time stamp clock has drifted significantly. Not all dataloggers set this flag.

PH5-format data does not include miniSEED flag information; this metric will always return a value of 0 for data in the IRIS PH5 archive.

This metric can be used to identify stations with GPS locking problems and data days with potential timing issues.

If using this metric with the rrds service, be aware that a value of 0 (zero) can either mean that

• the datalogger detected 0 instances of this condition, or
• the datalogger does not set this flag, so it is unknown whether or not this condition occurred.

Unless all channels in an rrds request are known to set this flag, requesting only data with a count of 0 will not necessarily omit all data for which this condition occurred.

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

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

• Request 24 hours of data for a single N.S.L.C.
• Count and report the number times this binary flag is set to 1.

value – number of times this flag is set to 1 that day
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)

Not all dataloggers set this flag. For those that do not, a value of 0 does not necessarily mean that the GPS has failed to lock.