1. PQLX - A Station Assessment & Data Quality Control System
Applications and Uses

2. 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

3. 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

4. Multi-Platform: Linux, MAC OS, Solaris
Source code for PQLX is freely available for download via WWW from:
Publicly Available, and Fully Searchable, Website for Bug Reporting and Enhancement Requests:
i?product=PQLX

5. Installation and Setup
External Software Dependencies
MYSQL - from
PQL II (to resolve GTK+ dependency) - from
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

6. 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
(twig as user rt) /us-shared/x86/pqlx is the startup scripts area for production runs, TA final, and testing in the cron area)

7. 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

8. 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

9. 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...

10. 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

11. 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

12. PSD’s:
Following algorithm of D. McNamara
Automatically Computed for Channels Named:
BH*, LH*, HH*, EP* At the DMC, only BH and LH
Additional Channels to Analyze Easily Added to Database

13. Server-Side PDFs:
Server Computes System PDFs for Each Channel at Each Execution and Stores the Probabilities Themselves in the Database, i.e., including these Plots:
Total PDF of all PSDs
Last Month of Available PSDs
Last Last and Last Last Last Month of Available PSDs
Last Week of PSDs
Current Year of PSDs
Last Year of PSDs
Future Development will Create .png Plots for easy WWW Publication

14. GUI Functionality PQL II - Trace File View Functionality (But does not
A single GUI Application Provides for all Client-side Access to the Database and Trace Data.  This GUI is Comprised of Several Systems Relating to Various Ways of Looking at the Data:
PQL II - Trace File View Functionality (But does not
Display Contents of Entire Trace File
Magnification of Trace Data Selection - Zooming, Overlay, Filtering, etc.
Fourier Transform of Selection
Multiple Simultaneous Data Views
Header Data View

15. Trace File View

16. Magnify View

17. Fourier Transform View

18. Simultaneous Data View

19. Header View

20. 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

21. System PDF View

22. PDF Request View

23. PDF Detail View

24. 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

25. (Configurable Display continued)
Display days of data/statistics per screen
Display channels per screen
Display only Specific Stations & Channels
Traversal in Time & Station/Channel List

26. STN Viewer - Coverage Mode

27. STN Viewer - Data Mode

28. 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

29. 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.

30. 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:

31. Station Performance

32. Meta-Data Accuracy
Bad Response File Information Visible in PDF Plots

33. Bad Units
Acceleration Instead of Velocity
Input Units
Extra Zero in Response File
Results in Tilted PSD:
Low Amps at Low Period
High Amps at High Period
Corrected Response

34. Bad Units
Displacement Instead of
Velocity Input Units
Missing zero in Response File
Results in Tilted PSD:
High Amps at Low Period
Low Amps at High Period
Corrected Response

35. Bad STS2 Gain
Used 20,000 counts/volt
Instead of 1500 counts/volt
Resulting in low corrected
Amplitude across spectrum.
Corrected Response

36. Noise Feature Analysis
Selection of Noise Feature in PDF Viewer Detail Screen
Precise Date and Times of Occurrence
Waveform (Time Domain) Display of PSD

37. Diurnal Variations

38. Earthquakes

39. Rogue Waves

40. Nuclear Tests

41. 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)

42. Missing Data

43. Data Gaps

44. Mass Re-Centering

45. Future Developments
The following functionality is being Considered for Future Development:
PDF Animations
More Advanced Data Analysis
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

46. Credits
The following Organizations (listed alphabetically), Through Direct and Indirect Funding, have made this Software possible:
IRIS - Data Management Center, Seattle, WA
IRIS - PASSCAL Instrument Center, Socorro, NM
National Science Foundation, Washington, D.C.
United States Geological Survey - Golden, CO