Summary
This metric shows the time spans of data gaps encountered within the requested time period, calculated at query time. It processes the times of data availability based on information stored in the rapidly-accessible IRIS SEED and PH5 archive database index (ts_index), as returned by the service.iris.edu/fdsnws/availability and service.iris.edu/ph5ws/availability web service.
The ts_channel_gap_list metric is currently a prototype that will eventually become a standard MUSTANG metric. .
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 lists duration, start and end times for data gaps.
Data Analyzed
Traces – one N.S.L.C (Network.Station.Location.Channel) per measurement
Window – from start time to the end time of the request
Data Source – IRIS miniSEED archive database time series index (ts_index)
SEED Channel Types – All Time Series Channels
Algorithm
- Request availability web service trace extents for the time duration on each matching N.S.L.C.
total_duration = request_end_time - request_start_time;
- For x entries/data segments returned,
- Calculate length of down-time for each segment:
segdt(x) = segment_endtime(x-1) – segment_starttime(x)
- Report segdt(x), endtime(x-1) as gap_start, starttime(x) as gap_end when segdt(x) > 0
- Calculate length of down-time for each segment:
Metric Values Returned
value – the data gap duration in seconds
target – the trace analyzed, labeled as N.S.L.C.Q (Network.Station.Location.Channel.Quality)
start – the start time of the data gap (UTC)
end – the end time of the data gap (UTC)
lddate – UTC date/time the measurement was made
Notes
If the user specified request end date does not include hour:min:sec, then it defaults to 00:00:00
