Thurs Nov 12, 13:45

PQLX - A Station Assessment & Data Quality Control System

Applications and Uses

Overview

PQLX System Technical Aspects

Software: Components, Installation and Setup

System Architecture: Server-Side Database & Client-Side GUI

Functional Aspects

Data Formats and Requirements

Analysis Statistics Computed by Server

GUI Functionality Provided by Client

Data Quality Control Possibilities

PDF Plots and Noise Feature Analysis

Future Developments

Technical Aspects

All Software Components Are Open-Source

Server-side Database - MYSQL

Client-side Database - gdb - GNU

Graphics Library - GTK+

FFTW - Fast Fourier Transform Library - MIT

miniSEED Data Reader, libmseed - IRIS DMS

evalresp - SEED Response File Reader - IRIS DMS/ISTI

TauP - Travel Time Calculation, algorithm - R. Buland & Chapman, updated by B. Kennet

Multi-Platform: Linux, MAC OS, Solaris

Source code for PQLX is freely available for download via WWW from:

http://www.iris.edu/software/pqlx/

Publicly Available, and Fully Searchable, Website for Bug Reporting and Enhancement Requests:

http://wush.net/bugzilla/PQLX/describecomponents.cgi?product=PQLX

Installation and Setup

External Software Dependencies

MYSQL - from http://mysql.org

PQL II (to resolve GTK+ dependency) - from http://passcal.nmt.edu

Entire System Written in C (if travel time tables are used in new version, you will need a fortran compiler)

Compilation and Installation via a single command- (scripted)

Provides Clear Indication of Success or Failure

PQLX Database created via:

Database Definition File

Script to read definition file and create database

System Architecture

Server-Side:

MySQL Instance Holds One or More PQLX Databases

pqlxSrvr - Server Process (one per database) Analyzes all waveform data, uploading all Analysis Results to Database:

Can be set up via cron for regularly scheduled execution

Scalable - Number of CPUs to use Specified at Execution Time- up to 4 currently

Re-runnable on Renewed Data - All statistics are Replaced when Data is Updated with Newer Version

Scripts - Several Scripts are provided to manage the database - ideally, there is no need to be directly involved with MySQL itself

Client-Side:

GUI Access to a PQLX Database:

As a Local Database:

Client and Database Reside on the Same Machine

Client and Database Reside on Same Local Network

As a Remote Database:

Client has Access to the Internet

Database Server is Visible on the Internet

Client Application is Fully Multi-Threaded for Efficiency Purposes

Functional Aspects

Data Requirements

Data can be Provided in ANY of the Following Formats (these also may be mixed within a single database instance):

miniSEED

SAC

SEGY

AH

nano

DR-100 -Spregnether

File Format is Auto-Detected, no Need to Explicitly Specify

File Definition is Read from Header, not File Name.  Thus, no Requirements for a Specific File Name Structure

Data can be Provided in Any Directory Tree Structure, Under One or More Base Directories

Response File in rdseed Output Format, One Channel per File, All Time Ranges

Server Constructs Database Contents Based on the Existence of Data - New Station/Channel Data Can be Added At Any Time...

Analysis Statistics

The PQLX Server is Responsible for Reading All Data/Trace Files, Writing All Statistics to Database

Data File Statistics (Meta- and Computed):

Start and Stop Times

Length

Maximum / Minimum / Mean

Total Gaps: Their Locations and Length

Total Overlaps: Their Locations and Length

Channel Statistics:

First and Last Date of Existence of Data

Total Number of Traces

Trace Data Maximum - max / min / mean

Trace Data Minimum - max / min / mean

Trace File Gaps - max / min / mean

Trace File Overlaps - max / min / mean

Trace File View

Magnify View

Fourier Transform View

Simultaneous Data View

Header View

PDF/ PSD Viewer

Connection to Specific PQLX Database

Plot System PDFs Stored on Server-Side Database

Plot User-Defined PDF Based on Date and Time Parameters

Sub-Select of PDFs Returning:

PDF of PSDs Intersecting User-Defined Sub-Selection

PSD Start Times and Durations

Trace Data Corresponding to PSD of Sub-Select, i.e., User is Able to go from Frequency Domain to Time Domain

System PDF View

PDF Request View

PDF Detail View

STN (station) Viewer

Connection to specific PQLX Database

Bird’s-Eye View of Station/Channel Statistics & Data

Existence of Data

Gaps and Overlaps

Pop-Up Statistics and PDF Corresponding to Time Period on Display

Configurable Display

Coverage Mode - Display vs. Database Info, i.e., no Waveform Data. Thus, not Necessary to have Access to Trace Files/Waveform Data Itself.

Data Mode - Waveform Data Display

(Configurable Display continued)

Display 1 - 60 days of data/statistics per screen

Display 1 - 36 channels per screen

Display only Specific Stations & Channels

Traversal in Time & Station/Channel List

STN Viewer - Coverage Mode

STN Viewer - Data Mode

In Development:

Event Record Sections

Align Waveform Data on Predicted Arrivals

Align Waveform Data on User Picks

Sort on Epicentral Distance

Simple Data Analysis

Integrate/Differentiate

Deconvolve Data - Remove Instrument Response

Cross-Correlation of Traces

As well as the GUI Client, Additional Client-Side Functionality Includes:

Scripts to Extract PSD and PDF Data from the Database.This allows the user to extract actual analysis data, either PSD or PDF format, done by specifying date and time bounding parameters for their own specific use.

Data Quality Control & Station Assessment

The following aspects of Data Quality Control are Possible to Manage and Identify with PQLX, i.e., WHAT:

Overall Station Performance

Channel Data Existence Displayed in STN viewer

Identify Instrument Problems

Gaps and Overlaps

Displayed in STN viewer: Identify Data Transmission Problems, e.g., Data Dropouts, Telemetry Issues, etc.

Displayed in PDF Plot:

Station Performance

Meta-Data Accuracy

Bad Response File Information Visible in PDF Plots

Bad UnitsAcceleration Instead of VelocityInput UnitsExtra Zero in Response File

Results in Tilted PSD: Low Amps at Low Period High Amps at High Period

Corrected Response

Bad UnitsDisplacement Instead of Velocity Input UnitsMissing zero in Response File

Results in Tilted PSD: High Amps at Low Period Low Amps at High Period

Corrected Response

Bad STS2 Gain

Used 20,000 counts/voltInstead of 1500 counts/volt

Resulting in low corrected Amplitude across spectrum.

Corrected Response

Noise Feature Analysis

Selection of Noise Feature in PDF Viewer Detail Screen

Precise Date and Times of Occurrence

Waveform (Time Domain) Display of PSD

Diurnal Variations

Earthquakes

Rogue Waves

Nuclear Tests

Quality can be Controlled in the Following Ways:

Daily Inspection and Perusal of Database Contents via GUI Application

Automatic Publication of Server-Side PDF Plots to the WWW as Part of the PQLX Server’s Execution

Future: User-Defined Triggers/Alerts Automatically Generated when PQLX Server Uploads Statistics, e.g.:

Maximum Gap Threshold

PSD Value Out-Of-Range (vs. HNM/LNM)

• PSD Value Within a Specific Range (vs. user-defined attribute)

Missing Data

Data Gaps

Mass Re-Centering

Future Developments

• The following functionality is being Considered for Future Development:

• PDF Animations – DONE!

• More Advanced Data Analysis

• For example Particle Motion

• Server and Database Management via Client-Based GUI Interface

• Normal Operating Bounds definition specific to Channel, i.e., a station/channel-specific HNM and LNM

• User-defined Noise Feature, e.g., PSD is above HNM

• Automatic Noise Feature Detection against User Definitions and Reporting, e.g., alert when PSD produces data in a specific noise and frequency range

Credits