1. Status and Advances on the Acoustic Positioning System for KM3NeT Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011

2. The deep sea acoustic positioning system The acoustic positioning is a mandatory subsystem for the detector providing: 1)Acoustic guide during the deployment of the telescope structures and infrastructures 2)Optical module position during the telescope operation Requirements: relative positioning accuracy: <20 cm (less than OM diametre) absolute positioning accuracy: <1 m to optimize pointing resolution no interference with the optical detectors easy installation data acquisition/transmission system compliant with KM3NeT electronics Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011

3. The deep sea acoustic positioning system Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 Key elements for the Acoustic Positioning System (APS) -Auto-calibrating Long Baseline of acoustic transceivers anchored in known and fixed positions. -Array of acoustic sensors (hydrophones) moving with the Detection Unit mechanical structure -Auxiliary devices: compasses, CTD, sound celerimeters, current metres -Data analysis system on-shore Hydrophone position calculation TDoA (Time Difference of Arrival) T Emit (LBL) – T Receive (Hydrophone) Geometrical Triangulation Hydrophone position calculation TDoA (Time Difference of Arrival) T Emit (LBL) – T Receive (Hydrophone) Geometrical Triangulation LBL transceivers Detection Unit Hydrophone

4. Proposed Acoustic Positioning System for the KM3NeT Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 Minimal autocalibrating LBL (autonomous or cabled) Definitive autocalibrating LBL (connected to KM3NeT shore clock) LBL transceivers on JB or DU bases Hydrophones on the DU storeys Minimal autocalibrating LBL (autonomous or cabled) Definitive autocalibrating LBL (connected to KM3NeT shore clock) LBL transceivers on JB or DU bases Hydrophones on the DU storeys Autonomous LBL Absolute positioning - Triangulation of LBL with a GPS linked acoustic array (fish) onboard a ship - Use LBL surface echo to measure transceiver depth Preliminary

5. Proposed Acoustic Positioning System for the KM3NeT Junction Box transceivers Detection unit hydrophones or piezos Detection unit hydrophones or piezos T emit sound trigger synchronous with detector clock T receive sound synchronous with detector clock Embedded in the data flow ECAP piezo INFN hydro UPV/CPPM FFR

6. Implementation of the hydrophone data chain Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 ADC 24 bits (stereo) Storey Control Module Adds GPS Time Sends Acou-data to shore On-Shore Storey Control Module Data Parsing Associated science Acoustic Positioning Acoustic Data Server ADS Hydros or piezos + preamps optical fiber link Point to point storey (DOM) connection Ethernet Hydrophone frequency range:few Hz < f < 70 kHz ADC dynamic range24 bits (18÷20 bits effective) ADC sampling frequency192 kHz (96 kHz optional) Master clock time GPS time added off-shore (25 ns resolution) Acoustic data transmission rate32 bits @ 192 kHz  6.2 Mb/s (1 hydro) Tested solution

7. Hydrophones and Preamps – the NEMO experience Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 SMID hydrophones and preamps (+ 38 dB gain) Sensitivity and pressure calibration measured and certified by NATO – URC (La Spezia) SMID hydrophones and preamps (+ 38 dB gain) Sensitivity and pressure calibration measured and certified by NATO – URC (La Spezia) Radiation lobe 30 kHz 50 kHz Hydrophone + preamplifier moulded in deep sea cable 7.5 m length Hydrophone sensitivity calibrated at NATO - URC (40 hydrophones) Measured differences ≤ ±2 dB Relative Hydrophone sensitivity variation with hydrostatic pressure at 20 kHz 300 Bar 400 Bar Measured variations ≤ ±1 dB

8. Dynamic range and noise floor Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 Expected performances for INFN hydro Beacon pulse of 32 kHz 180 dB re 1 µPa @ 1m Test at LNS – March 2011 noise floor peaks due to e.m. ambient noise <1 kHz acoustic ambient noise + 50 Hz New measurement to be done with improved with shielded set-up Total power = - 70 dB re 1 V Baseline = - 130 dB re 1 V /sqrt (Hz) UPV/CPPM FFR INFN SMID INFN Acou-board Sensitivity = -170 dB re 1 V/uPa Sensitivity = -152 dB re 1 V/uPa

9. Timing Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 SCM on-shore SCM off-shore Inserts time in acoustic data Optical link Signal generator Acou Board preamp Trigger Signal Time of Trigger known (accuracy < ns ) Sinusoidal wave Measurement of offshore electronics latency = 166 ± 1 µs  75 ns delay with respect to trigger signal 1 us Average = 166.1 us 10 kHz < f < 80 kHz Preliminary  < 100 ns 1 µs is conservatively assumed to take into accout hydrophone latency, dimensions etc.. GPS

10. LBL Transceivers – the UPV / CPPM experience Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 Resonance Frequency30 kHz Transmit Voltage Response, TVR133 dB re µPa/V @ 1m Receive Voltage Response, RVR-193 dB re V/µPa @1 m Useable Frequency range (transmit)20 kHz – 40 kHz Beam patternRadial: Omni Axial: Toroidal (60°) Efficiency50% Input Power300 W (2% duty cycle) Operating Depth (Metres)Unlimited Free Flooded Ring (FFR) – Sensor X-30 Tests performed at the large hyperbaric tank at IFREMER-Brest Pressure dependence study : tested up to 440 bar

11. Test on implementation of the LBL transceivers chain Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 SMC on-shore SMC off-shore Optical link Signal Emission Board Acou Board Trigger Time of trigger known (accuracy < ns ) Signal to transmitters FFR SCM on-shore Transmits GPS time Sends user trigger Sends user commands and settings SCM off-shore Inserts time in acoustics data Interfaces commands and trigger to SEB Signal Emission Board RS-232 connection from shore allows to: Set amplitude to emit Set frequency (or signal) to emit Set repetition rate SCM on-shore Transmits GPS time Sends user trigger Sends user commands and settings SCM off-shore Inserts time in acoustics data Interfaces commands and trigger to SEB Signal Emission Board RS-232 connection from shore allows to: Set amplitude to emit Set frequency (or signal) to emit Set repetition rate Digitized Data Slow Control Board RS232 GPS FFR SMID preamp

12. KM3NeT joint acoustic tests Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 trigger time suspescted e.m. pulse on H1 and H2 at 166.1 +7.5 = 173.6 µs acoustic pulse on H1 (about 15 cm) acoustic pulse on H2 (about 30 cm) Tests at UPV (May 2010) – In water Emitter Signal Emission Board INFN Acou-board

13. Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 KM3NeT joint acoustic tests ECAP Piezos inside a NEMO OM with PMT on no e.m contribution from the OM electronics !! Total power = - 56 dB re 1 V Baseline = - 130 dB re 1 V /sqrt (Hz) ECAP Piezo INFN SMID Total power = - 45 dB re 1 V Baseline = - 90 dB re 1 V /sqrt (Hz) Test at LNS – March 2011 noise floor Peaks: e.m. ambient noise <1 kHz acoustic ambient noise + 50 Hz New measurement to be done with improved with shielded set-up Sensitivity = -143 dB re 1 V/uPa Sensitivity = -170 dB re 1 V/uPa Pay attention: In this test gain was reduced (-20 dB). For full gain saturation is expected for typical beacon signal (180 dB @ 1m) at D<500 m !!!

14. Future Work Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011 -Tests with the full system in water pool (e.g. Toulon)  summer 2011 - Installation of 2 FFR, 8 SMID and 2 ECAP piezos on the NEMO Phase II tower - Software developments : data distribution data analysis source reconstruction Interface with SeaTray ?

15. Giuseppina Larosa, IGIC-UPV KM3NeT General Meeting, Nikhef 28-31/03/2011