1. Improved Direction of Arrival Methods for Oceanographic HF Radars Brian Emery Department of Mechanical Engineering, and Marine Science Institute University of California, Santa Barbara brian.emery@ucsb.edu Libe Washburn Department of Geography, and Marine Science Institute University of California, Santa Barbara

2. cycles per hour HF radar Power Spectrum of Ocean Currents Mooring

3. cycles per hour HF radar Power Spectrum of Ocean Currents Mooring 6 cm/s

4. Why are HF radar ocean currents noisy?

5. Why are HF radar ocean currents noisy? And What can be done about it?

6. 1.Ocean Current Radars 1.Direction of Arrival Method 1.Simulation Based Evaluation 2.Summary

7. 1.Ocean Current Radars 1.Direction of Arrival Method 1.Simulation Based Evaluation 2.Summary

9. IOOS: about 135 systems $5 million annual expense

12. Three Antennas

13. Antenna Directional Response

14. Monopole

15. Antenna Directional Response Loop 1 Monopole

16. Antenna Directional Response Loop 1 Loop 2 Monopole

17. How to map currents 1) Bragg Scattering -> Signal 2) Doppler Shift -> Velocity 3) FMCW -> Range 4) MUSIC-> Direction

18. 1.Ocean Current Radars 1.Direction of Arrival Method 1.Simulation Based Evaluation 2.Summary

19. MUSIC Schmidt, Ralph O. "Multiple emitter location and signal parameter estimation." Antennas and Propagation, IEEE Transactions on 34.3 (1986): 276-280.

20. MUSIC - Signal and noise subspaces - More elements than emitters - Noise Gaussian

21. MUSIC - Signal and noise subspaces - More elements than emitters - Noise Gaussian

22. Doppler pre-processing

24. MUSIC -Limited snapshots -SNR is often low -Signal uncorrelated > 1 o

25. 1.Ocean Current Radars 1.Direction of Arrival Method 1.Simulation Based Evaluation 2.Summary

32. Ziskind and Wax, 1988 Maximum Likelihood Localization of Multiple Sources by Alternating Projection

34. 1.Ocean Current Radars 1.Direction of Arrival Method 1.Simulation Evaluation 2.Summary

35. Why are HF radar ocean currents noisy? And What can be done about it?

36. Why are HF radar ocean currents noisy? - SNR often low - Array design - Too many emitters

37. What can be done about it? - More pre-processing - Alt DOA methods

38. Improved Direction of Arrival Methods for Oceanographic HF Radars Brian Emery Department of Mechanical Engineering, and Marine Science Institute University of California, Santa Barbara brian.emery@ucsb.edu Libe Washburn Department of Geography, and Marine Science Institute University of California, Santa Barbara

44. MUSIC Schmidt, Ralph O. "Multiple emitter location and signal parameter estimation." Antennas and Propagation, IEEE Transactions on 34.3 (1986): 276-280.

45. MUtiple SIgnal Classification “MUSIC”

46. 75 cm/s