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Explore current testing facilities, the need for more facilities, facility design requirements, testing new designs, upgrading facilities, policies for facility use and data access, and support for test facilities.
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Testing & Testing Facilities – charge to breakout group • Who/where are current testing facilities? Do we need more? • Facility design – minimum requirements • How to test new designs (e.g. SCG, laser designs, digital seismometers, etc) • What is required to upgrade test facilities to support new designs? • Policies for test facility use and data access • Support for test facilities IRIS Seismometer Workshop
Current test facilities • Sandia FACT site • ASL - USGS • Pinon Flat Observatory - UCSD • Pinedale Seismic Research Facility - AFTAC • Manufacturers • Stations • Various others • Black Forest Observatory in Germany • Conrad Observatorium in Austria • etc IRIS Seismometer Workshop
Current test facilities • Do we need more? • Group favors upgrading ASL and Pinyon Flat (PFO) facilities as needed • ASL has granite tunnels & boreholes • PFO is building new, quieter facility • Best chance of getting NSF funding for one or both of these facilities IRIS Seismometer Workshop
Parameters to be measured (these detemine test facility design req.) • Sensitivity & transfer function • Self noise • Bandwidth • Clip level • Stability of sensitivity & transfer function over time, temperature • Cross axis coupling • Dynamic range (get from noise & clip level vs. f) • Sensitivity to environmental effects • Temperature, pressure, magnetic field variation, RF. Etc • Shock (shipping survival) IRIS Seismometer Workshop
Facility Design – Minimum Requirements • Quiet over all frequency bands of interest • Long term reference seismometers operating • Shake table capability • Isolation table (stable table) • Temperature chamber? Use dry ice & John Tsitouris air circulation technique (less expensive) • Auxiliary measurements needed • Pressure, temperature, wind, magnetic, solar • Small seismic array and/or microbarographic array • High resolution data acquisition systems + other test equipment • Acoustic absorption on walls to reduce acoustic effects on instruments • Capability to test both vault and borehole dryland instruments (implies vaults/tunnels and boreholes) IRIS Seismometer Workshop
Facility Infrastructure support • Expert testing personnel • Training of new testers and users • Education and Outreach component • Test equipment • Shipping, storage • Electricity • Network connection • Phones • Documentation (a set of specific tests and results documented in a standard way in a report) • Etc. IRIS Seismometer Workshop
How to test new designs? • Discussion centered on what to do with “inherently digital” seismometers in which the analog signal may not be available • For proper coherence noise testing, the samples between channels need to be simultaneous (else noise testing needs to be done on isolation table) • Absolute timing of samples may be an issue • Treat seismometer as “black box” to be tested with available input (ground motion, cal input) and available output (digital or analog) • How to test Super Conducting Gravity Meters, Laser Interferometer devices not specifically discussed. Characterize as black box (see above). IRIS Seismometer Workshop
What is required to upgrade existing test facilities to support new designs? • Shake tables (both strong and weak motion) • Stable tables • Higher resolution digitizers may be necessary if seismometer noise levels go down significantly • Lower voltage rails may also be a problem. • LSB of 24-bit digitizer with 20 V peak full scale is 2.38 microvolts • LSB of 24-bit digitizer with 5 V peak full scale is only 0.6 microvolts • 25-bit resolution (or better) may be necessary IRIS Seismometer Workshop
Policies for test facility use and data access • Access • Manufacturers and other users should have open access • Test facility operator may need to recover costs for lengthy tests • Development testing may be proprietary, so data will be kept confidential unless permission granted by manufacturer • Test data from commercial off-the-shelf (COTS) seismometers will be made publicly available • Data access: Publish on web site and/or appropriate journal (e.g. Seismological Research Letters?) • Security • Site security (such as ASL test facility via Kirtland AFB) may be an issue for personnel from foreign countries IRIS Seismometer Workshop
Support for test facilities • Agency or host organization support • USGS • UCSD • Possible outside funding sources • NSF • NIST • IRIS • AFTAC • Manufacturers? Fees for testing? Try to avoid, if possible, except for lengthy, expensive testing programs. • Long term support? Always an issue. IRIS Seismometer Workshop
Additional Considerations • Proper installation techniques are very important, maybe at least as important as getting a replacement for the STS-1 • Workshop (at ASL? At UCSD?) to continue Standards for Seismometer Testing (SST) document • Change from “standards” to “guidelines”, add reporting guidelines • Need list of minimum tests to perform for each level of testing (such as Development, Qualification, Acceptance, Operational, Installation) • Absolute cal technique: Wielandt’s calibration table & software • Table can be purchased from Lennartz or can be built • Software available from Wielandt’s web site: www.geophys.uni-stuttgart.de/downloads • Tests appropriate for field instruments • Temperature, moisture, physical handling, ease of installation • Field test (install in a real or simulated field experiment) • Severe environment testing – test over range specified by manufacturer or by purchaser for special purposes (e.g. Polar use) • Testing during operation • Calibration through cal coil. How often? • Comparison to reference sensor IRIS Seismometer Workshop
More ideas • Strong motion testing • Tilt: Will instrument continue working properly after experiencing large tilt from local event? • Reproduction of known large displacements (e.g. CalTech pushcart tests of SM velocity instrument) • Clip level • Hysteresis effects • Clip level testing in general – all sensors • Different types of tests • Development • Design qualification • Acceptance (production units) • Operational • Installation IRIS Seismometer Workshop
ASL Location on Isleta Reservation IRIS Seismometer Workshop
ASL Seismometer Test Facilities (Boreholes) IRIS Seismometer Workshop
ASL Underground Seismometer Test Facility IRIS Seismometer Workshop
Testing STS-1 Seismometer in ASL underground vault IRIS Seismometer Workshop