RELEASABLE FOR CONSTRUISONS ENSEMBLE PUBLIC DISCLOSURE LA DÉFENSE DE DEMAIN ADDITIONAL VALUE ON TRACKING PERFORMANCE OF BPSK WAVEFORM IN CAS TRANSMISSION P. MARLIER UNDERWATER WARFARE DEPT. SESSION : ACTIVE AND MULTI-STATIC SONAR PROCESSING
CONTENTS RELEASABLE FOR PUBLIC DISCLOSURE Who ? • DGA Techniques navales What ? • BPSK CAS project Where ? When ? • The experimental setup How ? • The signal processing chain To what end? • Experimental results And then ? 2 • Future works 11/06/2018 DGA Techniques navales
RELEASABLE FOR Who ? PUBLIC DISCLOSURE DGA, the French Defence Procurement Agency Supervise defence equipment design and production Academic Research DGA Naval Industry French Navy Systems players Defence Programs S&T activities 3 11/06/2018 DGA Techniques navales
RELEASABLE FOR What ? PUBLIC DISCLOSURE CAS experimental project Enhance anti-submarine warfare frigates active capabilities Reflected waves Transmitted waves Pulsed sonar Continuous sonar Wave amplitude Wave amplitude Time Time 4 CAS enhances virtually the pulse repetition 11/06/2018 rate DGA Techniques navales
RELEASABLE FOR What ? PUBLIC DISCLOSURE BPSK continuous transmission Provide an additional observable dimension to the Kalman Filter in Cartesian Coordinates 𝑾 𝒔𝑼 North 𝑾 𝑼 𝑾 𝒔𝑪 Frequency 𝑾 𝑪 𝑾 𝑴 𝑾 𝒔𝑴 Reflected 𝒈 𝒔𝟐 𝑾 𝑴 Transmitted 𝒈 𝒖𝟐 𝚬𝒈 Time East Doppler-shift 𝚬𝒈 is related to the target kinematics 𝚬𝒈 = 𝒈 𝒔𝟐 − 𝒈 𝒇𝟐 = 𝒈 𝒇𝟐 . 𝑾 𝒔𝑼 = 𝒈 𝒇𝟐 . 𝑾 𝒔𝑴 + 𝑾 𝒔𝑪 𝒅 𝒅 5 𝑾 𝒔𝑪 = 𝚬𝒈 . 𝒅 − 𝑾 𝒔𝑴 11/06/2018 𝒈 𝒇𝟐 DGA Techniques navales
RELEASABLE FOR Where ? When ? PUBLIC DISCLOSURE The experimental setup Mediterranean Sea on July 2016 FREMM French Navy support CAPTAS-4 from Thales Defence Mission Systems Combined Active and Passive Towed Array System Continuous Active BPSK transmission CAPTAS-4 system Courtesy of Thales Defence Focus on fixed clutters Mission Systems 6 11/06/2018 DGA Techniques navales
RELEASABLE FOR How ? PUBLIC DISCLOSURE The signal processing chain BPSK continuous transmission 8 sub-band pulses From 1.0 kHz to 2.2 kHz 3.75 seconds for each sub-pulse Frequency (Hz) 7 11/06/2018 Time (s) DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Array made up of 128 hydrophones Matched filter triplets Beam Collapse Extraction Tracking High capabilities in port-starboard discrimination using cardioid beamforming Signal averaging on each triplet to simplify processing chain 8 11/06/2018 DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Beam width in broadside direction ~ 1° Matched filter 𝟑𝜾 𝟒 = 𝟔𝟏° 𝝁 Beam Collapse 𝑴 Extraction Beam spacing reduced to ~ 0,25 ° to reduce Tracking tracking input sampling noise Signal processed in the time domain Hamming window Temporal coherent processing 9 11/06/2018 DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Doppler extraction by cross-correlation Matched filter Clutter with low relative radial speed (+/-1knots) Beam Collapse Doppler range depending on detection relative bearing Extraction North + 𝑾 𝒏𝒃𝒚 High Tracking negative radial Doppler (Knot) speed Low 𝟏 radial speed High positive Fixed radial clutter − 𝑾 𝒏𝒃𝒚 speed 𝟏° 𝟘𝟏° 𝟐𝟗𝟏° East Detection Relative Bearing ( ° ) 10 Cross-correlation between received signal and 11/06/2018 “Doppler - shifted” transmission DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Merging cross-correlation results of each sub-band Matched filter of each ping in a given sector Beam Collapse Extraction Arrival time Arrival time Tracking Associated Doppler values Cross-correlation maximum level 11 11/06/2018 DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Tracking input from extracted data Matched filter 𝒖 Transmission time (s) Beam Collapse 𝝌, 𝒉 Array geographic position (rad, , rad ad) Extraction 𝒘 Array speed over ground (kn knots) Tracking 𝒍 Array course over ground (rad) 𝜾 Detection relative bearing (rad) 𝚬𝒖 Detection delay from transmission (s (s) 𝜽 Detection estimated Doppler (kn knots) 12 𝑻𝑶𝑺 Detection SNR (dB dB) 11/06/2018 DGA Techniques navales
RELEASABLE FOR How ? Triplet average PUBLIC DISCLOSURE The signal processing chain Beamforming Kalman Filter in Cartesian Coordinates Matched filter State Vector Beam Collapse 𝑼 𝒀 𝒍 = 𝒚, 𝒚 , 𝒛, 𝒛 Extraction Nearly Constant Velocity model Measure Vector Tracking 𝒛 𝒍 = 𝜾, 𝒆 𝑼 𝑼 𝒛 𝒍 = 𝜾, 𝒆, 𝒔 Same initial state for both filters Error prediction variance-covariance matrix adapted to each filter 13 11/06/2018 DGA Techniques navales
RELEASABLE FOR To what end ? PUBLIC DISCLOSURE Experimental results Statistics on Doppler distribution 0,5 0,5 Doppler (Knot) Doppler (Knot) Clutter detection Noisy area 14 11/06/2018 DGA Techniques navales
RELEASABLE FOR To what end ? PUBLIC DISCLOSURE Experimental results Increased prediction filter accuracy 15 11/06/2018 DGA Techniques navales
RELEASABLE FOR To what end ? PUBLIC DISCLOSURE Experimental results Faster prediction filter convergence 16 11/06/2018 DGA Techniques navales
RELEASABLE FOR In conclusion PUBLIC DISCLOSURE Processing continuous active BPSK wave transmission seems to provide bearing, range and Doppler measurement with a high detection rate Matched filtering with Doppler-shifted signal replicas allows fixed clutter detection Adding Doppler measure to the update vector shows good impact on Kalman Filter performance Prediction Accuracy Convergence Speed 17 11/06/2018 DGA Techniques navales
RELEASABLE FOR And then ? PUBLIC DISCLOSURE Future works Consolidate with more data Exploit cardioid beamforming Set other Doppler configuration (moving target) Tracking through collapse beams image processing THANK YOU FOR YOUR ATTENTION ! 18 11/06/2018 DGA Techniques navales
RELEASABLE FOR CONSTRUISONS ENSEMBLE PUBLIC DISCLOSURE LA DÉFENSE DE DEMAIN ANY QUESTIONS ? SESSION : ACTIVE AND MULTI-STATIC SONAR PROCESSING
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