Data Services Newsletter

Volume 14 : No 2 : Fall 2012

PQLX 2011.365 Goes Open Source

Screenshot of the latest PQLX release
Figure 1: Screenshot of PQLX showing station traces

An arrangement with Boaz Consultancy has allowed for the GPL open-source licensing of the latest version of PQLX to be possible. IRIS DMC offers both PQLX and PQL (known to some as PQL II) source code packages for download at the following address:

PQLX (PASSCAL Quick Look eXtended) is open-source software authored by Richard Boaz (Boaz Consultancy) for evaluating seismic station performance and data quality. The software primarily consists of a server and client but also includes data extraction and migration tools. Given waveform data and instrument response files, PQLX server calculates trace statistics, Power Spectral Densities (PSD), and Probability Density Functions (PDF)1 writing the results to a MySQL database for quick access.

PQLX is used at the IRIS DMC in conjunction with the Earthscope USArray project. Analysts review data from the 400+ active Transportable Array and Backbone Array stations on a regular basis, checking for issues such as instrument failures, poor data quality, high noise levels, and metadata inaccuracy. This quality control effort ensures that potential problems are detected early and that a high quality dataset is archived and made available to the research community.

PQL (PASSCAL Quick Look) is also available as a standalone download. PQL is a smaller, lighter version of the application, which does not include a MySQL database, PDF plotting, or the Station Viewer tool.

PQLX development has been made possible from funding by:


1 D.E. McNamara and R.P. Buland, Ambient Noise Levels in the Continental United States, Bull. Seism. Soc. Am., 94, 4, 1517-1527, 2004.

by Tim Ahern and Rob Casey (IRIS Data Management Center)

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