Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves
View Patent ↗A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.
1. A Dynamic InSAR imaging method, comprising:
sampling one or more fast-moving surface displacement waves from a plurality of moving platform positions utilizing a plurality of pulses from an electromagnetic radiation source and at least one antenna; and
reconstructing a plurality of phase differentials from said plurality of platform positions to produce a series of interferometric images of said waves.
2. The method of claim 1 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity greater than about 100 m/sec.
3. The method of claim 1 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity between about 300 m/sec and about 8000 m/sec.
4. The method of claim 1 , wherein said sampling further comprises sampling the ¼ crests and the ¼ troughs of said waves.
5. The method of claim 1 , wherein said waves have an amplitude of at least about 1 cm.
6. The method of claim 5 , wherein said source produces X-band microwaves.
7. The method of claim 1 , wherein said electromagnetic radiation source produces microwaves having a wavelength between about 1 mm and about 1 m.
8. The method of claim 1 , wherein said moving platform comprises an airborne platform.
9. The method of claim 8 , wherein said airborne platform comprises a jet aircraft.
10. The method of claim 1 , wherein said moving platform comprises a satellite.
11. The method of claim 1 , further comprising a dual-phase-center antenna.
12. The method of claim 1 , further comprising a pair of physically separate antennas.
13. The method of claim 1 , wherein said method includes along-track InSAR.
14. The method of claim 1 , wherein said method includes repeat-pass InSAR.
15. The method of claim 1 , where said method includes strip-mode InSAR.
16. The method of claim 1 , wherein said method includes spotlight InSAR.
17. A Dynamic InSAR imaging method, comprising:
sampling one or more fast-moving surface displacement waves from a plurality of moving platform positions utilizing a plurality of pulses from an electromagnetic radiation source and at least one antenna,
producing an offset phase center having a time lag t lag ,
subtracting a phase difference having said time lag t lag to produce a phase differential at each of said platform positions; and
reconstructing a plurality of said phase differentials to produce a series of interferometric images of said fast-moving surface displacement waves.
18. The method of claim 17 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity greater than about 100 m/sec.
19. The method of claim 17 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity between about 300 m/sec and about 8000 m/sec.
20. The method of claim 17 , wherein said sampling further comprises sampling the ¼ crests and the ¼ troughs of said waves.
21. The method of claim 17 , wherein said waves have an amplitude of at least about 1 cm.
22. The method of claim 17 , wherein said time lag t lag comprises the time it takes for a trailing, aft, phase center to travel to a position of a leading, forward, phase center, with t lag =B/V plat , where B is the distance between said aft and said forward phase centers and V plat is said platform velocity.
23. The method of claim 17 , wherein said electromagnetic radiation source produces microwaves having wavelengths between about 1 mm and about 1 m.
24. The method of claim 23 , wherein said source produces X-band microwaves.
25. The method of claim 17 , wherein said moving platform comprises an airborne platform.
26. The method of claim 25 , wherein said airborne platform comprises a jet aircraft.
27. The method of claim 17 , wherein said moving platform comprises a satellite.
28. The method of claim 17 , further comprising:
shifting a receive array by at least one column between a pair of receive channels to produce said offset phase center.
29. The method of claim 17 , further comprising:
turning on and off predetermined one or more outer conductor strips to produce said offset phase center.
30. A Dynamic InSAR imaging method, comprising:
sampling one or more fast-moving surface displacement waves from a plurality of moving platform positions utilizing a plurality of pulses from an electromagnetic radiation source and at least one antenna,
producing an offset phase center having a time lag t lag ,
subtracting a phase difference having said time lag t lag to produce a phase differential at each of said platform positions,
reconstructing a plurality of said phase differentials to produce a series of interferometric images having one or more sets of concentric rings associated with said fast-moving surface displacement waves.
31. The method of claim 30 , wherein said concentric rings includes one or more primary sets of concentric rings.
32. The method of claim 30 , wherein said concentric rings includes one or more primary concentric rings and one or more secondary sets of concentric rings.
33. The method of claim 30 , wherein said concentric rings includes one or more displaced sets of concentric rings.
34. The method of claim 30 , wherein said concentric rings include wave shadows.
35. The method of claim 30 , wherein said concentric rings include diffuse reflections.
36. The method of claim 30 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity greater than about 100 m/sec.
37. The method of claim 30 , wherein said fast-moving surface displacement waves comprise waves having a traveling velocity between about 300 m/sec and about 8000 m/sec.
38. The method of claim 30 , wherein said sampling further comprises sampling the ¼ crests and the ¼ troughs of said waves.
39. The method of claim 30 , wherein said waves have an amplitude of at least about 1 cm.
40. The method of claim 30 , wherein said time lag t lag comprises the time it takes for a trailing, aft, phase center to travel to a position of a leading, forward, phase center, with t lag =B/V plat , where B is the distance between said aft and said forward phase centers and V plat is said platform velocity.
41. A dual-phase-center InSAR apparatus, comprising:
a receive array capable of collecting a reflected radiation from an electromagnetic source,
a first channel receiver adapted to measure said reflected radiation collected from said array and;
a second channel receiver additionally adapted to measure said reflected radiation collected from said array, said first and said second channel receivers being further adapted to produce a predetermined phase center offset (B), with B being a predetermined baseline distance between an aft and a forward phase center, wherein a phase difference between said aft and said forward phase center enables the determination of a wave velocity of one or more fast-moving surface displacement waves.
42. The apparatus of claim 41 , wherein said phase center offset includes shifting said receive array by a column between said first and said second channel receivers to produce said baseline B, with B=(θλ/2π)(V plat /U seis ).
43. The apparatus of claim 41 , wherein said phase center offset includes turning on and off one or more conductor strips arranged on said receive array to produce said baseline B, with B=(θλ/2π)(V plat /U seis ).