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**Benthic Acoustic Stress Sensor (BASS): Electronics Check-Out ProceduresNovember 22, 1994**
Marinna A. Martini, U.S. Geological Survey, Woods Hole, MA 02543Albert Williams III, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
*U.S. Geological Survey Open File Report OF-93-722*
                                Contents
ForwardAbbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5I.  Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6II.  Recommended Test Equipment. . . . . . . . . . . . . . . . . . . . .  7III.  Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9IV.  BASS Transducer and Cable Check . . . . . . . . . . . . . . . . . . 23V. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Appendix A.  Other Signals of Interest . . . . . . . . . . . . . . . . . 25Appendix B.  Suggested Form for Recording Observations . . . . . . . . . 29Appendix C.  A Tattletale 4 BASS Program . . . . . . . . . . . . . . . . 33Appendix D.  MATLAB Script File for BASS Calibration . . . . . . . . . . 37
Forward
     The following is a series of test and calibration procedures for the OceanographicInstrument Systems (OIS) Benthic Acoustic Stress Sensor (BASS).  Although theseprocedures were written for a BASS system with a Tattletale 4 microcomputer, theyshould generally apply to those BASS systems with Tattletale Model 5 microcomputers.  
     Please send any comments or corrections to Marinna Martini at the U.S.Geological Survey, or to the address on the cover of this report.mmartini@usgs.gov

List of Abbreviations
CCW       counter clockwisediv       divisionDT-V      differential time-voltage (circuit board)m         metersma, mA    milliampsMHz       megahertzms        millisecondsmv, mV    millivoltsns        nanosecondspf        picofaradsp-p       peak to peaks         secondsV, v      voltsVDC       volts, direct currentus        microseconds

I.  Summary
     The procedures described here are presented so that a technician with limitedexperience with BASS can perform basic tests which, when executed properly, should bea thorough evaluation of the health of the system.  This is not intended as an in depthexplanation of how BASS works.  Should any significant problems be found, it issuggested that you contact the manufacturer, Oceanographic Instrument Systems, NorthFalmouth, MA.  The Tattletale controller is manufactured by the Onset ComputerCorporation, Cataumet, MA.

II.  Recommended Test Equipment
     The following equipment was used to perform the electronics evaluationsdescribed in this report.  Models used at USGS test facility are given as examples otherequipment with the same specifications may be substituted:1. Hewlett Packard Model 54601A 100MHz Oscilloscope:     Featuring four channel inputs, delay time and memory for trace storage and     recall.  This scope does not have a separate, external trigger input.2. Tektronix Model 7613 Oscilloscope:     Featuring two channel inputs, delay time, store and external trigger input.3. BASS sensor pod, submerged in water4. Extender board5. 21 VDC, 1.5 amp Power supply6. Computer with one RS232 serial port free7. Onset's TattleTools or other terminal emulation software.8. BASS Schematics9. Data Precision Model 3500 4 1/2 digit volt-ohmmeter 10. Onset TC-4 RS232 communications cable11. Tektronix AM503 Current Probe amplifier with model P6302 probe12. Oceanographic Instrumentation Systems (OIS) nanosecond delay test unit13. Capacitance meter
     The author has used a number of terminal emulation software packages tocommunicate with Tattletales rather than the TattleTools software provided by Onset. These procedures, therefore, have been written for use with any terminal emulationsoftware.
Use of trade names is for the purposes of identification only and does notconstitute any endorsement  by the USGS.

III.  Procedures

IV.  BASS Transducer and Cable Check
     Each sensor pod which makes a three axis current measurement uses a total ofeight acoustic transducers to do so.  These are generally rugged parts, however theircapacitance should be checked periodically and whenever there is any suspicion ofdamage.  To insure that no moisture can penetrate the sealed housing, capacitanceshould be measured after the transducer has been soaked in water for several days.  Thecapacitance is typically 1000 pf +/- 30 %.  Note that the true capacitance will be thecapacitance measured with the test leads connected to the transducer minus thecapacitance of the test leads by themselves.
     The electrical condition of the cables can also be checked by measuringcapacitance.  Once the capacitance for each transducer has been recorded, themeasurement is repeated through the cable.  A cable in good condition should notsignificantly differ from the capacitance reading at the transducer.

V. References1.   Morrison III, A.T.,  Williams 3rd, A.J., and Martini, M., 1993, Calibration of the          BASS Acoustic Current Meter with Carrageenan Agar: Institute of Electrical and          Electronics Engineers, Oceanic Engineering Society, OCEANS '93 Conference          Proceedings, vol. 3, pp. 143-148.2.   Trivett, D.A., Terray, E.A. and Williams 3rd, A.J., Error Analysis of an Acoustic          Current Meter,   J. of Oceanic Engineering, vol. 16, pp. 329-337.3.   Williams 3rd, A.J., 1984, An Acoustic Current Meter Array for Benthic Flow-Field     Measurements,   Marine Geology, vol. 66, pp. 345-355.