1. Application of 13 MHz SeaSonde Systems for Vessel Detection
Mike Smith1, Hugh Roarty1, John Kerfoot1, Josh Kohut1, Scott Glenn1, James Isaacson2, Don Barrick2, Hector Aguilar2
1Rutgers University Institute of Marine and Coastal Sciences, 2Codar Ocean Sensors,. Inc.
Introduction
In addition to surface current mapping, CODAR SeaSonde systems may be used in the detection of vessels. The SeaSonde software already detects ships to remove their signature from the data to avoid contamination of the surface current product. Here, we present work that we have done to improve these detections as we move toward a real-time detection system. Specifically, we discuss a case study using the Y/M Los Angles outside of New York Harbor, bistatic detections, and our new, real-time interface.
CSR Experiment
November 9, 2009
Y/M Los Angeles
Figure 1a: Vessels of Opportunity – Range, Radial Velocity, Bearing
Figure 1b: Vessels of Opportunity – Map
IIR Median
A pepper plot contains all signal peaks above a certain threshold (dB). Here, each signal peak is colored and sized by SNR on the monopole
Figure 2a: Best scenario for IIR, time averaged, filter.
Figure 2b: Best scenario for Median, Range and Doppler averaged, filter.
With the Median filter, the Los Angles was able to be detected 58% of the time compared with AIS data. This represents the best case scenario.
Figure 3a: Y/M Los Angeles – Range, Radial Velocity, Bearing
Figure 3b: Y/M Los Angeles – Vessel points overlayed on AIS track
CSR Experiment - Results
Figure 4a:
Left Column – Pepper Points per minute for every FFT and threshold
Right Column – Detection Rates for every FFT and threshold
Figure 4b: Median Sensitivity Study - Varying number of Doppler bins and sizes yields different results. In this test, best detection rates were from a window 5 range cells and 7 Doppler cells wide.
Monostatic vs. Bistatic Detections
Bistatic Vessel Detection has been implemented at our BRNT site. Results showed that bistatic detections can be advantageous in certain situations. The tug boat, “Dace Reinauer,” was detected in this study.
Monostatic
IIR Median
Bistatic
Figure 5a and 5b: Monostatic Pepper plots using IIR 256/6 and Median 256/8
Figure 5c and 5d: Bistatic Pepper plots using IIR 256/6 and Median 256/8
IIR 256/6
Monostatic Bistatic
Figure 6a: Monostatic Match Result – The red circle shows a time period where we were not able to detect the vessel.
Figure 6b: Bistatic Match Result – The red circle on the left displays the area that was not detected by Monostatic in Figure 6a. The circle on the right displays an area that is visible in monostatic range cells but not in bistatic.
Real-Time Vessel Detection
Real-Time software written in C code has been developed by Codar Ocean Sensors.
First implementation of the software was at SEAB located in Sea Bright, NJ on April 5th, 2011.
Real-time visualization is accomplished via a stand-alone MATLAB plotting GUI.
Future Goals:
Implement Real-Time Bistatic Detection in the summer of 2011 between Sea Bright, NJ and Belmar, NJ 13 MHz SeaSonde sites.
Acknowledgement. “This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number 2008.ST-061-ML0001.”
Disclaimer. “The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security.”
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