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Change in Q4120 filter parameters

June 30, 2003

The BDSN and MiniPBO Q4120 Quanterras will be reconfigured and rebooted at 5 pm PST today (July 1, 00:00 UTC) in order to change the FIR filter for the 100 Hz channels from acausal to causal. The affected stations are:

The new BDSN Q4120 station MNRC was upgraded yesterday, since it is a new station and continuous telemetry has not yet been installed.

This change is motivated by the desire to improve phase picking on the 100 Hz channels. This writeup by Bob Uhrhammer and Bob Nadeau describes how the change affects the data.

This change means that all Q4120/Q730 dataloggers operated by the BSL will use causal filters for sampling rates of 100 Hz and higher (The HRSN and NHFN have traditionally used causal filters for the higher sampling rates). Lower data rates will continue to use the acausal filters. This change does NOT apply to the BDSN sites with Q680/980 dataloggers, as they cannot be configured for causal filtering.

Updated instrument responses will be available soon.

The NCEDC is a joint project of the University of California, Berkeley and the USGS. Please send us email at or fill out our comments form if you have questions or comments about these changes.