System for measuring characteristic of scatterers using spaced receiver remote sensors

• US 6,512,996 B1
• Filed: 03/08/2000
• Issued: 01/28/2003
• Est. Priority Date: 03/08/2000
• Status: Expired due to Term

• Current Assignee: University Corporation For Atmospheric Research
• Original Assignee: University Corporation For Atmospheric Research
• Inventors: Praskovsky, Alexander A., Praskovskaya, Eleanor A.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/521,401
• Time in Patent Office: 1,056 Days
• Field of Search: 702/189, 342/26, 342/52, 342/104, 342/118, 342/147, 342/350
• US Class Current: 702/189
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/951 ground based
• CPC Class Codes: G01S 15/885 Meteorological systems
• CPC Class Codes: G01S 17/95 for meteorological use
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/539 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The system for measuring characteristics of scatterers by spaced receiver remote sensors uses a method based on calculation and analysis of the auto- and cross-structure functions for return signals. The method enhances operational capabilities of spaced receiver remote sensors by providing a diverse body of characteristics of scatterers at any elevation angle independently of a type of remote sensor, a type of scatterers, a number of scatterers and their spatial distribution within the illuminated volume. A list of characteristics includes (but is not limited by) the mean speed of scatterers, intensity of the speed fluctuations, and a set of indicators for identification of scatterers. The method is not so sensitive to ground clutter and hard targets as the existing methods are. The method allows to increase an effective signal-to-noise ratio for the existing spaced antenna remote sensors by using significantly overlapping antennas. The method allows to simplify the existing hardware by removing the quadrature-phase synchronous detector although it can be applied to the standard complex output signal.

Claims

1. A system for determining predetermined characteristics of scatterers extant in a predetermined volume of space, wherein said scatterers have at least one predetermined characteristic, comprising:

sensor means being capable of transmitting signals and receiving components of transmitted signals of known characteristics that are reflected from said scatterers wherein said scatterers are illuminated by a radio, acoustic, or light frequency signal transmitted in a beam pattern and wherein the sensor means comprises at least two receivers separated in at least one of a spatial dimension and directed to concurrently view said scatterers; and

means for processing said received components reflected from said scatterers using the structure functions for said received components to obtain data indicative of at least one of said predetermined characteristics of said scatterers.

2. The system for determining predetermined characteristics of scatterers of claim 1 wherein a remote sensor, comprising a pulse wave, or continuous wave transmitter, generates said transmitted signal, and said reflected components from said scatterers comprise a pure return signal component and a contamination component, said means for processing said received components comprises:

means for calculating an auto structure function for each of said at least two spatially separated receivers; and

means for calculating a cross-structure function for each pair of said at least two spatially separated receivers.

3. The system for determining predetermined characteristics of scatterers of claim 2 wherein said means for processing said received components further comprises:

means, responsive to said auto structure function and said cross-structure function, for generating said data indicative of at least one of said predetermined characteristics of said scatterers.

4. The system for determining predetermined characteristics of scatterers of claim 3 wherein said means for processing said received components further comprises:

means, responsive to said auto structure functions, for generating zero order coefficients to provide the moments of noise and effective gain factors of predetermined order.

5. The system for determining predetermined characteristics of scatterers of claim 3 wherein said means for processing said received components further comprises:

means, responsive to said cross-structure functions, for generating zero order coefficients to provide indicators for the predetermined identification of scatterers.

6. The system for determining predetermined characteristics of scatterers of claim 3 wherein said means for processing said received components further comprises:

means, responsive to said cross-structure functions, for generating first order coefficients to provide the mean speed components of said scatterers.

7. The system for determining predetermined characteristics of scatterers of claim 3 wherein said means for processing said received components further comprises:

means, responsive to said auto structure functions and said cross-structure functions, for generating second order coefficients to provide estimates for turbulence characteristics of said scatterers.

8. The system for determining predetermined characteristics of scatterers of claim 2 wherein said means for processing said received components comprises:

means for pre-processing said received components to reduce said contamination component.

9. The system for determining predetermined characteristics of scatterers of claim 8 wherein said means for pre-processing said received components comprises:

means for executing at least one process on said received components to reduce said contamination component from the class of processes including;

filtering of the random noise from said received components, using a clutter removal algorithm(s) on said received components, removing the mean values from said received components, normalizing said received components.

10. The system for determining predetermined characteristics of scatterers of claim 3 wherein said means for processing said received components further comprises:

means for post-processing said determined characteristics using a post processing algorithm from the class of processing algorithms including;

statistical analysis of all obtained estimates for the predetermined characteristics of the scatterers where said remote sensor can produce several estimates for some characteristics, joint statistical analysis of said characteristics of said scatterers at the analyzed time interval with those from the previous time interval(s), joint statistical analysis of said characteristics of the scatterers at the analyzed range with those from other close enough ranges, and identification of said scatterers in accordance with predetermined requirements by using a set of measured indicators.

11. The system for determining predetermined characteristics of scatterers of claim 1 wherein said sensor means comprises:

at least two spatially separated antennas, separated along a direction comprising a path said reflected components from said scatterers travel to said sensor means, and said at least two spatially separated antennas being focused on the same range.

12. The system for determining predetermined characteristics of scatterers of claim 1 wherein said sensor means comprises:

a single antenna which obtains at least two signals at slightly separated yet overlapping ranges.

13. The system for determining predetermined characteristics of scatterers of claim 1 further comprising:

means, responsive to said data indicative of at least one of said predetermined characteristics of said scatterers, for displaying and/or archiving said determined characteristics.

14. A method for determining predetermined characteristics of scatterers extant in a predetermined volume of space, wherein said scatterers have at least one predetermined characteristic, comprising the steps of:

activating a sensor that is capable of transmitting signals and receiving components of transmitted signals of known characteristics that are reflected from said scatterers wherein said scatterers are illuminated by a radio frequency signal transmitted in a beam pattern and wherein said step of activating comprises receiving said components from at least two receivers separated in at least one of a spatial dimension and directed to concurrently view said scatterers; and

processing said received components reflected from said scatterers using the structure functions for said received components to obtain data indicative of at least one of said predetermined characteristics of said scatterers.

15. The method for determining predetermined characteristics of scatterers of claim 14 wherein a remote sensor, comprising a pulse wave, or continuous wave transmitter, generates said transmitted signal, and said reflected components from said scatterers comprise a pure return signal component and a contamination component, said step of processing said received components comprises:

calculating an auto structure function for each of said at least two spatially separated receivers; and

calculating a cross-structure function for each pair of said at least two spatially separated receivers.

16. The method for determining predetermined characteristics of scatterers of claim 15 wherein said step of processing said received components further comprises:

generating, in response to said auto structure function and said cross-structure function, said data indicative of at least one of said predetermined characteristics of said scatterers.

17. The method for determining predetermined characteristics of scatterers of claim 16 wherein said step of processing said received components further comprises:

generating, in response to said auto structure functions, zero order coefficients to provide the moments of noise and effective gain factors of predetermined order.

18. The method for determining predetermined characteristics of scatterers of claim 16 wherein said step of processing said received components further comprises:

generating, in response to said auto cross-structure functions, zero order coefficients to provide indicators for the predetermined identification of scatterers.

19. The method for determining predetermined characteristics of scatterers of claim 16 wherein said step of processing said received components further comprises:

generating, in response to said cross-structure functions, first order coefficients to provide the mean speed components of said scatterers.

20. The method for determining predetermined characteristics of scatterers of claim 16 wherein said step of processing said received components further comprises:

generating, in response to said auto structure functions and said cross-structure functions, second order coefficients provide estimates for turbulence characteristics of said scatterers.

21. The method for determining predetermined characteristics of scatterers of claim 15 wherein said step of processing said received components comprises:

pre-processing said received components to reduce said contamination component.

22. The method for determining predetermined characteristics of scatterers of claim 21 wherein said step of pre-processing said received components comprises:

executing at least one process on said received components to reduce said contamination component from the class of processes including;

filtering of the random noise from said received components, using a clutter removal algorithm(s) on said received components, removing the mean values from said received components, normalizing said received components.

23. The method for determining predetermined characteristics of scatterers of claim 18 wherein said step of processing said received components further comprises:

post-processing said determined characteristics using a post processing algorithm from the class of processing algorithms including;

statistical analysis of all obtained estimates for the predetermined characteristics of the scatterers where said remote sensor can produce several estimates for some characteristics, joint statistical analysis of said characteristics of said scatterers at the analyzed time interval with those from the previous time interval(s), joint statistical analysis of said characteristics of the scatterers at the analyzed range with those from other close enough ranges, and identification of said scatterers in accordance with predetermined requirements by using a set of measured indicators.

24. The method for determining predetermined characteristics of scatterers of claim 14 wherein said step of activating comprises:

receiving said components from at least two spatially separated antennas, separated along a direction comprising a path said reflected components from said scatterers travel to said at least two spatially separated antennas, and said at least two spatially separated antennas being focused on the same range.

25. The method for determining predetermined characteristics of scatterers of claim 14 wherein said step of activating comprises:

a single antenna which obtains at least two signals at slightly separated yet overlapping ranges.

26. The method for determining predetermined characteristics of scatterers of claim 14 further comprising the step of:

displaying and/or archiving, in response to said data indicative of at least one of said predetermined characteristics of said scatterers, said determined characteristics.