photonics applied to coherent radar networks …
TRANSCRIPT
PHOTONICS APPLIED TO COHERENT RADAR NETWORKS FOR BORDER SECURITY
Salvatore Maresca1, Giovanni Serafino1, Filippo Scotti2, Leonardo Lembo1,3
Paolo Ghelfi2, Antonella Bogoni1,2
1TeCIP Institute, Scuola Superiore Sant’Anna, Pisa, Italy
2PNTLab, Consorzio Nazionale Interuniversitario per le Telecomunicazioni (CNIT), Pisa, Italy
3Italian Navy, Centro Supporto Sperimentazione Navale (CSSN), Vallauri Institute, Livorno, Italy
1st Maritime Situational Awareness Workshop MSAW 2019
Science and Technology meet operational needs
Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
- 2 -Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
▪ Photonic Technology for Distributed Radar Networks▪ Challenges in Maritime Surveillance▪ Distributed Radar Networks (Decentralized vs Centralized)▪ Photonics for Distributed Radar Networks
▪ Maritime Surveillance in the Port of Livorno (Italy)▪ The NATO-SPS SOLE Project▪ Simulation of the Maritime Scenario▪ Detection Applied to a Distributed Radar ▪ Preliminary Simulation Results
▪ Preliminary Photonics-Assisted Distributed Radar Network Architecture▪ Down-scaled System Architecture▪ Experimental Setup and Results
▪ Conclusions
OUTLINE
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PHOTONIC TECHNOLOGY FORDISTRIBUTED RADAR NETWORKS
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
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▪ TASKS▪ Detection▪ Tracking ▪ Classification▪ Identification
▪ AVAILABLE SENSORS▪ Synthetic Aperture Radar (SAR) imagery ▪ Automatic Identification System (AIS) ▪ Very High Resolution (VHR) imagery ▪ Coastal radars (e.g., HF, S, X bands) ▪ etc…
▪ CHALLENGES in RADAR SYSTEMS▪ Target RCS fluctuations (up to 25dB!) ▪ Sea clutter features (e.g., sea spikes)
▪ POSSIBLE SOLUTIONS▪ Multiband operation ▪ Multisensor operation
REFERENCE:M. Cerruti, M. Pastorino, A. Randazzo, F. Perra, and A. Guagnano, “Aradar cross section and radar performance evaluation tool for theearly stage ship design (ESSD) phase”, in OCEANS 2015 - Genova,May 2015, pp. 1–5.
Target RCS fluctuations
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
CHALLENGES IN MARITIME SURVEILLANCE
Sea clutter (S-band vs X-band)
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DECENTRALIZED Radar NetworkMultistatic Radar
REFERENCE:A. Bogoni, P. Ghelfi, F. Laghezza, “Photonics for RadarNetworks and Electronic Warfare Systems”, IET ScitechPublishing, DOI: 10.1049/SBRA516E, 2019.
CENTRALIZED Radar NetworkMultiple-Input Multiple-Output (MIMO) Radar
PROS:▪ Maximization of information from sensor fusionCONS:▪ Time and phase synchronization▪ Large-bandwidth links for signal distributionHOWEVER…photonic technology allows to overcome these problems!
PROS:▪ Local preprocessing at the slave nodes▪ Fair-bandwidth links for signal distributionCONS:▪ Complex slave nodes▪ Information from sensor fusion not truly maximized
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
DISTRIBUTED RADAR NETWORKS
Target Target
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▪ Excellent phase stability in multiband signal up/down-conversion▪ Preservation of phase stability upon signal distribution▪ A single photonic core manages multiple distributed radar heads (Centralized Architecture)!
Single-frequency
Laser
IF Waveform
Fiber Span
Photonics-basedRF Signal Distribution
E/O O/E
Signal Distribution
REFERENCE:G. Serafino, P. Ghelfi, et al., “Phase and Amplitude Stability of EHF-Band Radar Carriers Generated From an Active Mode-Locked Laser”,IEEE Journal of Lightwave Technology, Vol. 29, No. 23, pp. 3551 -3559, Oct. 2011.
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
PHOTONICS FOR DISTRIBUTED RADAR NETWORKS
Photonics-basedRF Signal
Generation/Reception
IF Waveform
E/O O/E
O/E
E/O
Multi-frequency
Laser
IF Signal
DSP ADC
DDS
TransmittedRF Waveform
ReceivedRF Signal
MASTER NODE
SLAVE/REMOTENODE
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MARITIME SURVEILLANCE IN THE PORT OF LIVORNO (ITALY)
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
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▪ Implementation/field trial of a multiband distributed MIMO radar network
▪ Optimization of target detection algorithms upon MIMO processing
▪ Fusion of 2D-ISAR images and 3D-ISAR imaging
Multistatic and Multiband Coherent Radar Fleet for Border Security
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
THE NATO-SPS SOLE PROJECT
The Project
http://www.sole-natosps.eu/
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System Geometry Extraction of scatterers
▪ For each TXk-RXl radar pair (k=1,...,M and l=1,...,N), the e.m. scatterers within the target silhouette are extracted.
▪ For simplicity, we assume one e.m. scattering element at the crossing of each TXk-RXl range cell.
▪ Based on the point-like scatterers, the received signal at TXk-RXl can be generated:
𝑟𝑘,𝑙 𝑡 =σ𝑚=1𝑁𝑠 𝑎𝑘,𝑙
𝑚 𝑠𝑘 𝑡 − 𝜏𝑘,𝑙𝑚 𝑒𝑗 𝜃 𝑡−𝜏𝑘,𝑙
𝑚 −𝜃 𝑡 + 𝑛𝑘,𝑙(t)
Symbol Description
𝑠𝑘(𝑡) Signal transmitted by TXk
𝑎𝑘,𝑙𝑚 Amplitude factor
𝜏𝑘,𝑙𝑚 Delay due to bistatic distance
𝑛𝑘,𝑙(𝑡) Additive white Gaussian noise (AWGN)
𝑁𝑠 No. of scatterers seen by TXk-RXl
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
SIMULATION OF THE MARITIME SCENARIO
Simulation of Extended Targets with a Distributed Radar
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Parameter Value
Skiff length (L) 10 m
Number of TXs (NTX) 3
Number of RXs (NRX) 3
Waveform LFM Chirp
Carrier frequency (fc) 9.7 GHz
Bandwidth (B) 100 MHz
Simulation Parameters
Spatial coherent MIMO processing allows to image the target!
No
n-c
oh
ere
nt
Co
he
ren
t
Λ 𝑟 𝑡 = 𝑐′
𝑘=1
𝑀
𝑙=1
𝑁
𝑒−𝑗2𝜋𝑓𝑐𝜏𝑘,𝑙 න𝑟𝑘,𝑙𝐵𝐵∗ 𝑡 𝑠𝑘
𝐵𝐵 𝑡 − 𝜏𝑘,𝑙 𝑑𝑡 + 𝑐′′
▪ Finally, the coherent MIMO cross-ambiguity function can be
estimated in the 2D Cartesian space:
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
SIMULATION OF THE MARITIME SCENARIO
Photonic 3x3 MIMO Radar
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Target detection is performed in the cell under test (CUT):
The CFAR criterion keeps the probability of false alarm below a preset acceptable level.
How do we choose the training cells?
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
DETECTION APPLIED TO A DISTRIBUTED RADAR
Cell Averaging – Constant False Alarm Rate (CA-CFAR) Detection
Symbol Description
𝑌 = Λ[r(t)] Detection statistic
𝐻1 target present in the CUT
𝐻0 target absent in the CUT
𝑇 Scale factor (deterministic)
𝑍 Noise power estimate
𝑌>𝐻1
<𝐻0𝑇 ∙ 𝑍
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Non-Coherent 3x3 MIMO Output
Rectangular Training Cells
Ellipsoidal Training Cells
The number of false alarms due to sidelobes is reduced!
Detection Outputs
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
PRELIMINARY SIMULATION RESULTS
false alarms!
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PRELIMINARY PHOTONICS-ASSISTED DISTRIBUTED RADAR NETWORK ARCHITECTURE
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
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REFERENCE:S. Maresca, G. Serafino, F. Scotti, F. Amato, L. Lembo, A. Bogoni, and P. Ghelfi, “Photonics for Coherent MIMO Radar: an Experimental Multi-Target Surveillance Scenario”, Proc. of the 2019 International Radar Symposium (IRS), 26-28 June 2019, Ulm, Germany.
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
PRELIMINARY SYSTEM ARCHITECTURE
Photonic 2x2 MIMO Radar Architecture
Radar network configuration:
▪ 2 radar transceivers
▪ Single-band @ 9.7 GHz
▪ 100 MHz bandwidth
▪ LFM chirp: PW 100 ns, PRI 50 μs
Fiber network configuration:
▪ One fiber pair for each RH
▪ Analog Radio-over-Fiber
▪ Bandwidth compatible with ITU
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Targets: ▪ 2 cylinders in metal net, 50cm x 34cm Ø
▪ Suspended to small quad-copter drones, 15÷20m above the floor
▪ Distance between targets: 3m
▪ Positions checked with GPS data from drone
15÷20 m3 m
21 m
1 km fiberTarget carried by the drone
In-field trials on TeCIP roof
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
EXPERIMENTAL SETUP
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Antennas HPBW ≈50°, target distance ≈18m → Cross-range Resolution: ≈15 m
Resolution Enhancement: 5x!
Non-Coherent vs Coherent 2x2 MIMO Results
Non-coherent MIMO Coherent MIMO
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
PRELIMINARY EXPERIMENTAL RESULTS
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CA-CFAR (ellipsoidal
training cells)
CA-CFAR (rectangular
training cells)
The coherent MIMO processing is capable of distinguishing the 2 targetsThe proposed modified CA-CFAR approach allows to detect them and to mitigate the
number of false alarms due to sidelobes!
CA-CFAR Detection Results
1 target detected
2 targets detected!
false alarms!
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
PRELIMINARY EXPERIMENTAL RESULTS
false alarms!
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▪ The contribution of photonic technology is decisive for developing distributed centralized radarnetworks, due to the high level of coherence granted upon signal generation, reception and distribution.
▪ A distributed multiband photonics-assisted 3x3 MIMO radar system will be operated in a real maritime surveillance scenario within the NATO-SPS SOLE Project.
▪ In this work, a preliminary operative scenario has been considered. A simple methodology has been proposed to simulate extended targets, by extracting the main scattering elements observed by each bistatic TX-RX radar composing the distributed radar network.
▪ A modified version of the CA-CFAR detection strategy has been proposed to cope with false alarms due to cross-range sidelobes in the MIMO cross-ambiguity function.
▪ Moreover, results of a preliminary down-scaled 2x2 MIMO system architecture working in an outdoor scenario have shown the potential of photonics-assisted MIMO radars, in terms of enhanced cross-range resolution and target imaging capability.
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
CONCLUSIONS
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THANK YOU VERY MUCH!
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
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PhD student and post-doc positions are available at Scuola Superiore Sant’Anna / CNIT in Pisa, Italy
If interested, please send an email to:
[email protected]@cnit.it
Maritime Situational Awareness Workshop (MSAW 2019), Villa Marigola, Lerici (SP), Italy, October 8-10, 2019
THE DIGITAL & MICROWAVE PHOTONICS GROUP