Early developments in absolute infrasound sensors

1. Early developments in absolute infrasound sensors Damien PONCEAU, CEA/DIF/DASE Sébastien PEYRAUD, CEA/DIF/DASE Patrick DUPONT, CEA/DIF/DASE Presented at the 2007 ISTW, TOKYO, JP on 15 November 2007

2. Presentation layout • Temporary experiments are more and more important: • Examples. • Requirements. • IS Sensors developments at CEA/DIF/DASE. Up to MB2000 • Early microbarometers developments: • Evolutions from MB2000 to MB2005. • A student IS sensor prototype. • MB2007 microbarometer. • Discussions.

3. Recent temporary measurements J. Guilbert, P. Harjadi, M. Purbawinata, S. Jammes, A. Le Pichon, B. Feignier, « Monitoring of Indonesian volcanoes with infrasound : preliminary results, SURvey of Volcanic Arc of Indonesia », Infrasound Technology Workshop 2005, PAPEETE. Power consumption need to be minimal

4. Recent temporary measurements A. Le Pichon, K. Antier, S. Vergniolle, M. Lardy, D. Drob, « Validating upper-wind models using infrasound from active volcanoes in Vanuatu », Infrasound Technology Workshop 2006, FAIRBANKS. Easy to transport and install Easy to calibrate Resistant

5. Recent temporary measurements A. Smirnov, V. Kunakov, A. Le Pichon, J. Guilbert, « Preliminary results of localization and characterization of steady infrasound source as detected by I31KZ », Infrasound Technology Workshop 2007, TOKYO. Power input range need to be increased

6. IMS Temporary measurements, new requirements • Some IMS requirements1: • Able to solve IS Low Noise Model @ 1 Hz. • Dynamic range > 108 dB. • New requirements2: • Portable, easy to transport and install. • Plug and play. • Resistant equipment operating in a very stable way and not sensitive to changes of geographical and meteorological conditions. • And others... 1Working Group B, CTBTO Preparatory Commission, « Operational manual for infrasound monitoring and the international exchange of infrasound data », Rev. 10, 7 Sep 2004. 2O. Sow, CTBTO Preparatory Commission, « Terms of reference, procurement of infrasound experimental array », CTBTO Preparatory Commission Request for proposal, ref. no. 2007-0213/SOW, 22 Aug 2007.

7. Presentation layout • Temporary experiments are more and more important: • Examples. • Requirements. • IS Sensors developments at CEA/DIF/DASE. Up to MB2000 • Early microbarometers developments: • Evolutions from MB2000 to MB2005. • A student IS sensor prototype. • MB2007 microbarometer. • Discussions.

8. IS Sensors@CEA/DIF/DASE : some developments French nuclear tests monitoring An infrasound microphone Acoustic bandpass behaviour1 very sensitive to environment. High thermal sensitivity. 1 Y. Rocard, « Calcul acoustique des microbarographes  », Archives, DASE, December 1969.

9. IS Sensors@CEA/DIF/DASE : some developments 70’s French nuclear tests monitoring An absolute infrasound sensor Acoustic lowpass behaviour1. Portable and robust.

10. IS Sensors@CEA/DIF/DASE : some developments 90’s IMS Proposal MB2000 microbarometer • Features: • 3 outputs for signal, calibration and monitoring. • High resolution @1 Hz. • Reduced uncertainties. • Extremely low thermal sensitivity. • Improved robustness.

11. DASE IMS sites typical specifications • For each site: • Volume: ~ 30 L • Weight: ~ 20 kg • Power consumption: ~ 7 W • Power input range : ~ [10.8; 13.2] V • Dynamic range: > 108 dB • Resistant equipment • And others… Pipes, meteo. and telecommunications not included

12. New “24 bits” acquisition systems • Common features1: • Portable & plug and play: • Power input range : ~ [9, 30] V • Volume : < 5 L • Weight : < 5 kg • Power consumption : < 1.5 W • Dynamic range (with symmetric input) > 120 dB • Resistant equipment • And others 1 A. Brisbourne, A. Paul, M. Alvarez, R. Sleeman, « State of the art digitizers », ORFEUS NERIES joint workshop, October 2007.

13. MB2005 microbarometer vs new requirements • MB2005 features1: • Portable & plug and play: • Power input range: ~ [10.8; 13.2] V • Volume & Weight: 3 L, 5 kg • Power consumption: ~ 3 W • Dynamic range: • Filtered output & symmetric output : > 108 dB • Static pressure range: ± 100 hPa • Resistant equipment 1MARTEC, « MB2005 User manual », ref. 14643-B MARTEC, 23 Jan. 2006.

14. Improved MB2005 microbarometer • New Specifications: • Portable & plug and play: • Power input range: ~ [9; 36] V • Volume & Weight: 3 L, 5 kg • Power consumption: ~ 1.5 W • Dynamic range: • Filtered & symmetric output: > 108 dB • Static pressure range: ± 100 hPa • Resistant equipment

15. Conclusion : current solution • Portable & plug and play: • Power input range: ~ [9; 30] V • Volume & Weight: < 20 L, < 15 kg • Power consumption: < 3 W (up to 2 W) • Dynamic range: > 108 dB (sensor) > 120 dB (digitizer) • Resistant equipment Pipes, meteo. and telecommunications not included 2 days batteries included. ~ 450 x 300 x 200 mm3

16. IS Sensors@CEA/DIF/DASE : some developments 1 Estimated from R. Bowman and G. Shields, « Ambient Infrasound Noise Estimates and Meteorological Conditions », Infrasound Technology Workshop 2005, PAPEETE.

17. MB2005 resolution optimisation

18. MB2005 resolution optimisation Optimised MB 1 Estimated from R. Bowman and G. Shields, « Ambient Infrasound Noise Estimates and Meteorological Conditions », Infrasound Technology Workshop 2005, PAPEETE.

19. 1 Estimated from R. Bowman and G. Shields, « Ambient Infrasound Noise Estimates and Meteorological Conditions », Infrasound Technology Workshop 2005, PAPEETE.l) Dynamic range optimisation (High impedance)  < 8 cm H <13 cm

20. MB2007 specifications

21. Conclusion : near future measuring chain • Portable & plug and play: • Power input range: ~ [9; 36] V • Volume & Weight: 5 L, 9 kg • Power consumption: < 800 mW (up to 300 mW) • Dynamic range: > 130 dB (sensor) > 120 dB (digitizer) • Resistant equipment

22. Conclusions • Temporary infrasound measurements induce new requirements for equipments. • Thanks to the recent developments in digitizers and infrasound sensors, more appropriate solutions are available. • Very interesting near future solutions appear.