IRIS Instrumentation Subcommittee

Summary

IRIS has the responsibility for providing modern instrumentation resources for the seismological research community. In 1997 the IRIS Executive Committee appointed an Instrumentation Committee to review the aging, vintage mid-80s hardware and to develop a plan for acquisition of next-generation instrumentation for all of the IRIS activities. The committee is chaired by Tom McEvilly , with Jim Fowler from IRIS management, and includes the following members: Tom Owens, Tom Pratt, Selwyn Sacks, Larry Ruff, Cliff Thurber and Frank Vernon, with liaison participants from the USGS, industry and IRIS Programs as appropriate.

The committee began with a Santa Fe workshop in November, 1997 (see report on IRIS website) that set the agenda followed since - exploring the evolving technologies in data acquisition, communications and seismometers. The approach taken in each area has been different. The first two developments involve normal advancements driven by broad consumer bases. Seismometers, in contrast, are a specialty product, with a relatively small user base; thus we must participate in any major innovations that will attain our goals of smaller, cheaper, lower power.

The main action items executed since that kickoff workshop have been:

• A user survey of PASSCAL investigators for suggested improvements in the new instrumentation
• Development support and acquisition of a new ORBCOMM communication link (2-way) to monitor and control remote data recorders

• Execution of a Non-Disclosure Agreement (NDA) with Teledesic in order to incorporate the proper technology for low-earth-orbit satellite internet connections when the constellation becomes operational
• Experimental use of IRIDIUM modems for data links
• Participation with USGS in planning for ANSS hardware (and reciprocal USGS cooperation in similar planning for USArray)
• Development of new design goals for the next DAS (Data Acquisition System), hosting a potential suppliers conference and call for proposals, and selection of two prototypes from the six proposals received for purchase and delivery in 2000
• Facilitated an industry-organized meeting on data standards for greater inter-supplier compatibility in acquisition hardware
• Initiated interaction with a number of accelerometer manufacturers that are not 'traditional' suppliers for seismology, resulting in some new possibilities for our sensor needs (new NDAs are being negotiated)
• Made plans to meet individually with the 'traditional' suppliers of seismometers for IRIS-style seismometry
• Begun serious planning for the huge impact of EarthScope on instrumentation requirements beginning in 2001
• Initiated interaction with UNAVCO on the possibilities for new-generation, inexpensive 2-frequency or L1 GPS receivers as auxiliary data streams in IRIS acquisition systems (an ad-hoc working group of the Instrumentation Committee will be following this activity)
• Began exploration of the 'Geophysical Observatory' concept in IRIS PASSCAL and GSN station instrumentation, with a planned ad-hoc working group investigating degree of interest and the potential elements/participants in such enhancements.

I.?Meeting 10 Jun99 at the Tenaya Workshop

Committee members - McEvilly, Fowler, Owens, Pratt, Vernon

Guests - Meltzer, Romanowicz, Levander, R. Johnson, Butler, Ahern, Simpson

A. Review of action items from committee meeting at Fall98 AGU:

"State of Seismometry" article (Sacks & Vernon, with possible student assistance), has been suggested to the authors, but it appears unlikely there will be a product this year.

Review/modification of DAS specs was completed and all comments received have been incorporated.

Satellite communications: We have entered into proprietary cooperative agreements with potential service providers at Internet speeds.

B. New business at Tenaya:

II. Subsequent developments:

EarthScope (ES) is an amalgamation of several research initiatives either underway of planned for large-scale equipment or facilities acquisitions in the next few years:

IRIS will have a major role in implementation and/or coordination of ES programs.

From our committee's perspective, an example of implications is clear in just the BB sensor requirements set out in USArray:

And of course there is a DAS for all 835 BB and 2000 SP sensors, along with telemetry considerations.

All of this bears heavily on what IRIS needs to plan for in the coming decade in way of instrumentation. Our simplistic view of sensor, acquisition and communication now has a much wider aperture.

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1. DAS solicitation.

We're receiving several proposals today for developing the new generation DAS. We've empaneled a proposal review subgroup consisting of:

• Doug Johnson
• John Collins
• Lee Powell
• Selwyn Sacks

who will meet with Jim and me in Denver in 2 weeks to review the proposals and recommend to us some course(s) of action.

We've been careful to insure confidentiality, with the following charge to the review panel:

The proposals that you are receiving are the result of a meeting that we had on September 01 with several potential suppliers to outline our design goals for the next generation of IRIS data acquisition systems. We reviewed also with them the large number of systems proposed in the EarthScope, ANSS and COCMOS initiatives as well as replacements for the core IRIS instrumentation - thousands of units, providing a unique opportunity for investment in developing new systems. We did not issue a formal RFP, rather we left it to the manufacturers to propose individual ideas for providing new instrumentation, and we encouraged innovation, so reviewing the proposals will rely on somewhat subjective criteria. We also guaranteed confidentiality for any aspects of the proposals considered to be proprietary.

We presented a general set of specifications and desires to the manufacturers (attached to this document) and asked the manufacturers to propose what they would envision as the next generation instrument and how it could be developed. We told them they could propose something that was essentially a purchase of prototype instruments or they could propose a more radical design study for which we would have to provide cost sharing.

This new instrumentation will have two primary uses. It will replace the current generation of PASSCAL hardware during the next 5 years, and it will also constitute the new acquisition system for the USArray (see http://www.iris.iris.edu/HQ/EarthScope/EarthScope.html).

We hope to get prototypes and start testing in 2000, in order to be in a position to purchase the "new generation" instruments sometime in 2001. All of this assumes that funds for IRIS and/or EarthScope are received.

To further complicate the issue, we may be looking at more than one instrument in this project. If USArray goes we can envision two separate instruments. One instrument would be a semi-permanent installation that "telemeters" the data back to a central site. This instrument would essentially produce a time-tagged data stream and communicate it back to the central site. We could afford to trade off a little power to get high quality reliable data. This instrument would only have enough storage on board to take care of data retransmission for expected communications outages. The second instrument could be one that is capable of operating in a stand-alone mode. While we believe that the future lies in the ability to make our instruments essentially nodes on the internet, for the next few years we will need to have the ability to record on site. This means this instrument might trade resolution or flexibility for low power and remote operation capability. However, we do not desire two different acquisition systems if one will do the job.

For this first phase we can acquire more than one instrument to test.

Your ratings should be based upon the following:

1. 1 Technical - 40%
   • If the instrument satisfies the design goals, how do you rate:
   • A/D and noise performance>
   • Communications
   • Packaging
   • Size and weight
   • Ease of operations
   • Reliability
   • Timing
2. 2 Developmental - 30%
   • Realistic development schedule
   • Probability of a successful product
   • Track record of the manufacturer
   • Role of IRIS during development
3. 3 Cost - 30%
   • Cost for prototype
   • Cost sharing
   • Realistic estimate of selling price

2. Standards Committee.

Following the Denver Potential Bidders' Conference in which there was substantial discussion about data standards among the manufacturers, Paul Passmore agreed to set up a workshop on standards for the industry people. It's to be held the Sunday before AGU in San Francisco. The invitational list is specific, and generated by industry. It will include some from the university and USGS community, but it is mainly for the hardware designers. Our Committee is invited to attend if any of you are interested. Here are some details:

Subject: Instrument Manufacturers Standards Committee

Date: Tue, 12 Oct 1999 10:00:11 -0500

Hello:

We have arranged for a meeting room at the Argent Hotel for Sunday, December 12 all afternoon. We will begin at 2 pm.

I would like to begin the meeting with a general discussion to identify specific areas that standards would be useful. Then I would request companies make presentations offering suggestions for specific or general standards. Those who are going to make a presentation should let me know in advance.

There may be some who want to contribute but cannot attend. Please send me your presentation and I will have it presented to the group.

For everyone making a presentation, I request an electronic copy so the entire set of presentations can be posted on the IRIS website.

Toward the end of the meeting we will vote to determine whether we meet again, and if so vote again to elect a chairperson for the next meeting.

Yours truly,

Paul Passmore

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1. Highlights of the 14Dec99 short meeting at AGU:

Members - McEvilly, Fowler, Owens, Pratt, Ruff, Thurber

Liaison - Hutt, Simpson

Guests - Harold Bolton & Kent Anderson (USGS)

Topical issues and ad-hoc working groups

• GPS incorporation implications for DASs, (dual-frequency, L1, etc), details of projected costs, power and data implications, feasibility
• Acquisition, deployment, scheduling, operational, etc. issues for management of USArray
• ;Communications issues for migration to real-time full internet linkage for GSN, PASSCAL, USArray systems
• Assessment of potential new sensors, i.e., reviewing specs., arranging testing, calibration, etc.

The point was made that contracts for new hardware should be sure to include appropriate descriptions of anticipated system developments, even if they are not ready to be incorporated at the time of ordering.

The concept of the Ad-hoc Working Group is for one Instrument Committee member to act as Coordinator of 2-3 other 'specialists' in a clearly focussed look at one of the topical issues in order to advise the Instrument Committee on specific questions.

At this time we are asking Larry Ruff and Tom Owens to consider leading the first Ad-hoc Working Groups on GPS and Communications, respectively, because these topics are in the early stages of serious discussions. We are also asking for statements of interest in any of the above topics, as this new mode of operations evolves.

2. Sensor developments

Since the AGU meeting we have been asked to enter a Proprietary Information Agreement (PIA) with Endevco on their newest accelerometer technologies. We also have been approached by Wilcoxon Research and PMD in response to our general inquiry and specification summary for instruments that could potentially be used in the IRIS/EarthScope/ANSS/COSMOS initiatives. Besides these 'non-traditional' suppliers, we are in the process of setting up one-on-one visits in April to our 'traditional' European suppliers to explore the next-generation sensor question.

The prototype DAS acquisition contracts with Reftek and Quanterra we expect to clear with ExCom in their meeting at Socorro on 24-25Jan00.

3. Information request from NSF

We were asked by Jim Whitcomb on short notice to provide some highlights of the instrumentation development efforts in IRIS for an internal NSF presentation on the MRE. We generated the summary of the committee history and major efforts that is used earlier in this review.

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Not a lot of visible activity since the last report at the end of January, but steady progress on several fronts:

DAS Prototype recommendations have been accepted by ExCom, funds have been authorized, and two systems each from Refraction Technology and Quanterra have been ordered. There are high similarities between the two systems - both feature timing/digitizing engines separated from their networking or recording subsystems. We hope to have tested and accepted the new prototypes by the end of this year. Previous distinctions between PASSCAL and GSN acquisition systems have largely disappeared in these new instruments, so that either DAS can serve GSN, ANSS, USArray, or PASSCAL needs with minor reconfigurations. Both designs can operate at power levels less than one watt, and we expect to be able to purchase them in quantity for less than $10K. We have initiated a dialog with the two suppliers on new technical features we hope to see incorporated eventually, and the various manufacturers have begun discussions among themselves on issues of standardization in these types of instruments. I think we can now put the DAS development behind us while we await the first prototypes.

Sensors are our current priority, and we are actively pursuing possible options for new designs of broadband or intermediate period seismometers that feature much reduced size, weight, power and cost with improved transportability, while delivering noise levels that will satisfy typical PASSCAL or USArray requirements. We have begun a study of actual noise levels attained in PASSCAL broadband experiments over the years, as well as for GSN and other permanent broadband stations. This information will provide ground truth for minimum sensor performance required for deployable broadband systems. We expect to enter Proprietary Information Agreements with some non-traditional suppliers of accelerometers for earthquake studies, e.g., fiber-optics, piezoelectric, silicon micromachined, etc. designs. Meanwhile, we are talking seriously to our 'standard' seismometer suppliers about the same issues, with a visit by Jim and me to our European sources scheduled for next month. We have convinced ExCom and told our suppliers that IRIS is willing to share development costs, if necessary, to move forward with exciting and promising new sensor designs.

Communications developments are out of our hands (and our price range). We must await implementation of new broadband technologies offering inexpensive internet access if we want to have 100% near-real-time links to every GSN, USArray, ANSS and PASSCAL station. This goal is going to have to see Teledesic-style capabilities (internet in the sky) for its attainment. at least 4-5 years off (but the anticipatory hooks need be in our acquisition systems).

Our great idea of Working Groups for special issues, forged at our AGU meeting in December, seems to have been stillborn. We've all been busy, and maybe there has not been a coordinated attempt to establish these groups, but the two we started with are in fact needed. The specter of USArray landing on IRIS's plate next year is scary. I hope we can get the communications (Owens) and Geophysical Observatories (Ruff) groups organized soon to begin to think about just how we're to control and exercise this monster.

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We had a fairly busy meeting at the Workshop on 09 May. We discussed:

The 'Jim&Tom did Europe' trip. I will append the trip report at the end of this, and not review it here. I apologize if I had not sent it out earlier - I had intended to, but must have simply forgotten, then assumed I had done it. The only follow on is that we have a price and delivery for two of the 'digitizer included' CMG3s from Guralp that we want to purchase and test (it would save on cost of sensor + separate digitizer by several thousand $$) and we are following closely Guralp's improvements promised in instrument consistency and robustness.

ANSS - now has an Oversight Committee chaired by Kaye Shedlock with six members (including Tim A.) who are in the early stages of setting up Subcommittees for various tasks, and we're told that there will be representation from our Committee on those as appropriate.

Finally, we all agreed with a suggestion (by David, I believe) for a USArray #1 demo at Socorro, as a practical showpiece for exploring configurations for USA stations.

Since the meeting, we have had more contact with SODERN on the IPG Mars seismometer development, and are providing encouragement for its commercialization.

We also learned from Bob Hutt that the Chinese delegation will arrive in Albuquerque soon to arrange testing of their broadband sensor(s) later this year.

European Sensor Trip 08-15 April 2000 Tom McEvilly & Jim Fowler

EarthData

The visit to EarthData was done to provide us with a chance to find out more about the corporation and to see how the prototype DAS for Potsdam is progressing. EarthData is part of the Kenda Group. The Kenda Group is a small company (50 employees) which specializes in special purpose electronic systems. The company was founded about 25 years ago, and is still privately held by the original founders, with whom we met. The historical source of projects is mainly from the military and power industries, apparently with a traditional focus on data acquisition and monitoring systems, with long-term support. Many products are special 'one-off' systems.

EarthData has developed a 24 bit digitizer and a seismic recording system to go along with it. There are currently almost 100 units in the field mainly with the British Geological Survey. Their design goals call for 'connectorless' systems insofar as possible, and expect to use the new (100 Kbaud) cellular technology when available. They are currently developing the next-generation instrument for Potsdam. This instrument has requirements very similar to what we want for PASSCAL. Delivery of the Potsdam unit is about 4-6 weeks late and is now scheduled for around the first of June.

They are trying to develop the technology to use temperature sensors to compensate for the DC drift due to thermal shifts in the digitizer. The DC offset is measured as a function of temperature. The information will be stored in a table that will be referenced to apply compensation during operation.

EarthData will build multiple prototypes of the Potsdam instrument. We should have an opportunity to test the instrument sometime this summer.

Guralp

The purpose of the visit to Guralp was to ascertain his current production capability, delivery and consistency. The Guralp facility has expanded into several thousand sq. ft. of space in three buildings within a fairly modern industrial park for what appear to be small businesses, and there are approximately 35 people currently at the facility. They now have a test facility in the lab and a lower noise site near-by with telemetry capability back to the lab. Data from all of the sites is available on the local network in real time. The assembly and testing procedures are impressive. A great deal of in- house software has been generated specifically for monitoring the process and generating unit-specific testing and fabrication records. The physical facilities appear to be very modern, with laminar-flow hoods and a (new) clean room reflecting attention to dust control in fabrication.

Guralp is currently producing instruments at the rate of about 400 per year. This includes CMG-3 (ESP and T) instruments and CMG-40T instruments with some CMG- 5 and PEPP instruments. Two people produce CMG-1's. Four people produce CMG-40T's and four people now produce CMG-3's. We were told that >1000 each of CMG3 and 40T instruments have been delivered.

The CMG-3ESP and 40T have natural periods of about 1 Hz. The natural period of a 3T is about 1/2 HZ. . All three of the sensors have the same feedback board with different parameters used to produce the desired outputs. The ESP pendulum is unique in that the structure is completely symmetric with respect to the plane through the center of mass in the boom. This is dynamically superior in dynamic response to boom structures having undesirable overturning moments of inertia.

The current Guralp sensors with a sensitivity on the order of 2000 v/m/s cross the low noise model between 1 and 2 Hz. With a sensitivity of 10000 v/m/s this intersection occurs at 8 or 10 Hz.

The systems feature a novel option in which the digitizing engine is installed within the seismometer case, above the feedback electronics - a configuration purported to produce a stable thermally stratified air column that does not introduce noise into the seismometers. This option may still be in late stage development, although we viewed such a unit. There are several possible outputs available, including TCP, RS 232 and 422. The digital output from the digitizer board is optically isolated. Conventionally, the analog output can be recorded by using a Guralp or other digital recorder. Guralp uses the Crystal 24 bit A/D. Dick Kromer has tested it and gives it 'normal performance' grade. There is a capability for up to 16 auxiliary analog inputs that will be sampled at 4 sps at 16 bits. Eight of the inputs are reserved for mass positions, temperature and pressure.

The compact GPS unit has all of the circuitry built into the antenna structure. The unit can be run in continuous mode or power-cycled. In power cycle mode the cycle interval is dependent on the change of temperature (to minimize possible internal clock drift) as well as the programmed cycle interval. The cpu clock (19MHz) drives the system clock (no phase-locked-loop).

A digital output CMG-3T adds an increment of about $3K for the internal digitizer. If this instrument (or the CMG-3ESP version) can be produced to meet delivery and consistent quality requirements, it would be a strong contender for the USArray (and other broadband) deployment. Reasonable large-order discounts presumably would be available, making this system very attractive (especialy if a substantial part of USArray might operate real-time without full on-site backup recording.

The goal of Guralp is to produce a true digital sensor. The PEPP sensor is a "pseudo" digital sensor. The displacement sensor is part of the delta-sigma digitizer. The feedback is still analog, however. The output of the circuit is of the same format as the Crystal chip so that the same filters can be used to decimate the data.

Streckeisen

The visit to Streckeisen was to see the manufacturing facility, and to explore the possibility of getting a significant increase in production for USArray/ANSS needs. The company occupies the fairly large third floor of a 4-story industrial-style building. The workspace is open, with all office, engineering, fabrication and testing space occupying various areas and benches. The visual impression, sustained in our tour, is one of a laboratory for skilled craftsmen - and that's basically what it is. The two 'artists' are Streckeisen and his #2 person, Franz. Streckeisen himself personally built the now- discontinued STS-1, while Franz assembles and tests every STS-2, the production rate could not be increased more then about 20%. The production rate for the STS-1 was very small. There are about 7 employees.

All mechanical parts are heat cycled when received. Each of the two springs is heat treated with different times and temperatures, because they need to have opposite temperature coefficients when installed in parallel, to attain a zero net coefficient. All of the large (6.8 uF) integrator capacitors are tested in two different ways. First for linearity and second for self noise at high voltage. Coils are wound at the plant.

Assembly begins with springs, then mass-lock assembly (very unit- specific), coil installation, and pendulum period adjust to infinity. Capacitor plates are installed - all of the washers holding the plates are hand-selected to make sure the plates are parallel. This is done visually (if you take the capacitor plates apart, you must remember where the washers go!).

During final test they run a calibration on the sensor. Each element is calibrated independently. The 120-second corner is determined using the coil to drive the boom. The gain of the system is determined by running each element on a shake table that is set up to shake along the axis of the element. The measurement is made using a 2 second sine wave. The high-frequency response is an approximation - an extension of the 2-second calibration point. The mixer resistors for the u,v,w->x,y,z transformation are estimated and then trimmed in the circuit to the correct values. Final gross calibration is done with the units assembled and pressure cycling of +/-30 mbars and cal-coil drive at low and high frequencies. The measurements are then fit with a curve to a using 11 poles and 4 zeros.

All completed units are run in a test facility (a massive concrete shelter) for one week where they are subjectively compared to a reference (up to 5 systems can be tested simultaneously). They are cycled +/- 30 deg C and temperature coefficients are checked.

When Streckeisen repairs an instrument, even with such common repairs as replacing the hinges, he runs the sensor through all of the check out and calibration tests. That is the only way that the 'transformed' x,y,z transfer function (depends on all 3 components) can be assured (n.b. - caution to university technicians).

Institut de Physique du Globe de Paris and SODERN

The purpose of this visit was to see if the developments being done on the Mars seismometer might be able to be implemented in a version suitable for IRIS. SODERN is an aerospace company working with IPG to develop the Mars Netlander seismometer (SEIS-NL), along with many other satellite sensor packages. SODERN is hoping to be able to use this technology to develop a land- and ocean bottom- based seismometer (SEIS-03) for commercial applications. The company is 8 years old and specializes in neutronics, space applications and optics. Annual income is about $40 M with 310 employees. For the last 4 years it has been a Phillips company.

The current work is the second Mars seismometer developed by this group. The first effort was the Mars 96 (OPTIMISM) seismometer. This unit was a vertical unit which drew only 25 mw of power. The unit was lost when the Russian launch vehicle exploded in 1996. The Netlander unit is designed to be a 3 component unit with the individual sensors mounted in a Galperin configuration (same as STS-2). However, because of weight considerations the unit scheduled for launch will only have 2 components mounted back to back to give vertical motion and one horizontal component.

The Netlander sensor has the following design goals:

• High sensitivity: 10**-10 ms**-1Hz**(1/2)
• Total mass: 1.9 Kg
• Power: < 600 mw
• Low sensitivity to pressure and temperature
• Free period: below 1Hz with 80g boom mass
• High Q pendulum
• Special steel for low thermal drift
• Balance expansion of pendulum and springs to compensate for temperature
• Seismic output: 10**-2 Hz - 50 Hz
• Tidal output: DC - 10**-2 Hz
• Shock: 200 G over 20 msec.
• Operating range: -40 C to +60 C

1998 tests of original prototype showed the following:

• Free period =3D 1 sec
• Q =3D 1000
• power =3D 500 mw
• sensitivity at least 10db below the Low Noise Model
• MTQ=3D15 was achieved (STS-2 is 10), so theoretical noise is excellent

The earth seismometer is called SEIS-03 will be a modified version of the Netlander. The overall specs are similar, however, the goal will be to make this unit easier to manufacture and cheaper to produce. The modified specs are:

• Bandwidth: DC - 100 Hz
• Automatic leveling: up to +/- 20 degrees of tilt
• Power: < 1 watt
• Total weight: 8.5 kg
• Dynamic range: > 150 dB
• Operating temperature -40 C to +60 C.
• Temperature sensitivity: +/- 20 C without mass recentering
• Shock: Drop from 1 meter without damage, well packed
• Mass lock: Lock during transportation, unlock during automatic installation
• Installation: Fully automatic

Summary: It looks like our best approach for USArray is to plan on perhaps a split between STS-2 and CMG, based on likely delivery and the tight schedule of the MRE account (assuming it begins in FY2001). Second in risk, with substantial cost savings, would be to try to use the CMG with the integral digitizer and decide what percentage of the Array needs backup recording on site. Lastly, with high risk but great payoff in performance and ease of installation would be to help get the SEIS-03 developed within a year and beat the price down with a quantity order. Other than these options or combinations thereof, there isn't much else we can do using our traditional suppliers for broadband sensors.

It is possible that alternative sensors will be found. The Chinese have three sensors they claim to be equivalent to a STS-2, Geotech is working on the KS2000, and PMD is working to improve their MET broadband sensor. SEIS-03 commercial development could be successful. It is also possible that a competitive "non-traditional" sensor could be developed from conventional accelerometer technology by someone like Endevco, Wilcoxon, Analog Devices, etc. The latter possibility is more likely to impact strong-motion or short-period sensor needs than low-noise broadband devices. It is very unlikely, however, that any new sensor working at the low noise model could be fully tested and put into quantity production in less than 2-3 years. If for some reason the USArray MRE account is open beyond 2006, the possibility of a new sensor is enhanced.

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Sensor testing. We set up a test facility in the BKS vault and had Bob Uhrhammer do some careful comparisons of our standard operational systems with commercially available piezoelectric accelerometers. Identical time periods, side-by-side locations on the pier, 24-bit acquisition, analyses of noise and local earthquakes, deconvolution of instrument responses, etc. were employed to get hard data on the performance of some commercial accelerometers in the 'low-noise' categories compared to STS-1, STS-2 and FBA-23 sensors in routine operation.

The purpose (besides simply being an interesting exercise) is to show the manufacturers just how their off-the-shelf units compare with our standard earthquake seismometers, so that they can evaluate the potential of their next-generation devices in terms of demands coming in USArray, PASSCAL, ANSS, COSMOS, etc.

We have entered a Proprietary Information Agreement with Endevco,and will likely do the same with Wilcoxon (where Jim and I will visit on August 16). I have not been able to elicit similar expressions of interest from either the MEMS or Fiber Optics (Analog Devices or Litton as examples), but I'll keep trying. Endevco and Wilcoxon both employ primarily piezoelectric technologies. I have not heard anything from PMD in some time, but we understand that they are working on a feedback system for their broadband sensor.

The initial comparisons are encouraging - present PZT technology can do a good job in a mid-noise-level site like BKS out to about 10 sec period, but not beyond. The manufacturers are looking at possible schemes to push to about 30 sec. We'll be watching and cheering them on.

The USArray #1 demo at Socorro is still planned as a practical showpiece for PR and for exploring configurations for USArray stations.

We continue to hear from SODERN on their IPG Mars seismometer commercialization, and we continue to provide encouragement.

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Attendees:

Committee members, McEvilly, Fowler, Hutt, Ruff, Sacks, Thurber, Vernon Other IRIS, Alvarez, Butler USGS (ANSS folks), Benz, Shedlock

Report:

Sensors. Discussion of new broadband sensors, e.g., PMD and Geotech, and our ongoing investigation of potential non- traditional designs (e.g., Endevco and Wilcoxon piezoelectric). Testing of these sensors is underway or planned at Berkeley, and the Kinemetrics and RefTek strong motion sensors (Episensor and 131-02) will be included. Fowler and McEvilly plan visits to both RefTek and Kinemetrics in January, to talk about sensors, among other things. In an assessment of actual noise environments achieved in typical temporary deployments, Mary Templeton has begun to run the network noise analysis routine provided to IRIS by Bob Uhrhammer on selected PASSCAL broadband deployments. GNS performance is also being evaluated , so that we soon will have a good idea of the average and best noise levels seen in both permanent and temporary deployments of broadband sensors.

DASs. Discussion of the expected deliveries of the two prototypes under contract (Quanterra Q330 and RefTek's new unit). The Q330 is expected first, and the RefTek unit later this year. The pressure is not great for completion, since there is not yet major funding for quantity purchases of either unit. Butler (GSN) reported on the planned testing of the SAIC (UCSD) DAS and the Q730 by Sandia (Kromer) to determine suitability in various applications. The SAIC unit was not entered into the IRIS DAS competition in the fall of 1999, but it is being pushed for IMS and IRIS/IDA upgrades, thus the plans for testing.

Communications. Fowler described an upcoming test of a newly available, low-cost Direct-TV style, 100 kb satellite telemetry link. The $500 hardware cost and $70/month charge makes it a competitive means for wireless internet access. IRIS application would be in th e USArray data acquisition and in PASSCAL telemetered array deployments. ANSS applications could be for remote regional and national broadband stations. Vernon is arranging for testing of a link to UCSD in the PASSCAL telemetered array in operation at Parkfield.

ANSS meeting. The first meeting of the ANSS Instrumentation Subcommittee followed the IRIS meeting, a practical arrangement given the facts of three common members (Hutt McEvilly, Vernon) and several overlapping issues. Shedlock and Benz had also participated in the IRIS committee discussions. ANSS is planning for installation over 5 to 7 years of:

• 6000 Urban strong-motion systems (half each structural and free-field installations)
• 1000 Regional broadband systems (30 sec to 30 Hz)
• 100 National network systems ( <0.01 hz to ~10 or 20 hz).

the anss subcommittee charge differs from that of our iris committee in that it will recommend standards and specifications to be used in procurement of the right equipment for the anss systems listed above.

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