niyiyu / pnwstore Goto Github PK

This is a known issue from obspy. When obspy reads an miniSEED stream, it reads only the start time, sampling rate and the number of samples. Then obspy will calculate the end time of the trace on-the-fly. Usually, the sampling rate is not accurate enough to have a perfectly accurate end time, meaning that the waveform will shrink or expand. This is negligible for short trace, e.g., 30 minutes for 1 data points for traces@100Hz. However, when you query a day-long trace, the misfit could be up to ~50 samples, which is about 0.5 seconds. The solution is querying a shorter stream when use obspy.read(), which is not implement by pnwstore yet.

When streaming waveform data from pnwstore, the client would return one more or less data point compare to what the user would get from IRIS. This tiny misfit would be amplified much bigger if the user resample the streams later. This is a known issue and should be solved for the purpose of reproducibility.