Method for cross-range enhancement of real-beam radar imagery

• US 8,063,817 B2
• Filed: 08/27/2009
• Issued: 11/22/2011
• Est. Priority Date: 08/27/2009
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Christianson, Paul
• Primary Examiner(s): GREGORY, BERNARR E
• Application Number:
  US12/549,074
• Publication Number:
  US 20110050485A1
• Time in Patent Office: 817 Days
• Field of Search: 342/21, 342/22, 342 25 R- 25 F, 342/175, 342/176, 342/179, 342189-197, 342 82-103, 342 70- 72, 342/159, 342/118, 342/146, 342/147, 375/300
• US Class Current: 342/191
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/89 for mapping or imaging

Abstract

Methods and apparatus for enhancing the resolution of a radar image in the cross-range direction. An example method includes receiving a plurality of received power samples in the cross-range dimension as the radar antenna scans and calculating a window function from the antenna beam response pattern. Then for each of a plurality of positions of the window function along the azimuth axis, multiplying the received response pattern by the window function at that position, yielding a product function for each position. Finally, the method includes calculating an estimated azimuth bin offset, resulting estimated target location, and a reflected power value corresponding to the integral of the product function from the product function of each position. A reconstructed azimuth bin array developed from the estimated target locations and reflected power values is substituted for the original received cross-range received power values, yielding a resolution-enhanced map image.

Claims

1. An apparatus for acquiring and displaying a radar image, the apparatus comprising:

an antenna configured to receive a reflected radar signal;

a processor configured to convert the received radar signal into a received power function versus azimuth, including generate a map image from the received power function versus azimuth by multiplying the received power function versus azimuth by a window function; and

a map display configured to display a resolution-enhanced map image based on the received radar signal.

2. The apparatus of claim 1, wherein the antenna is configured to scan an azimuth.

3. The apparatus of claim 2, wherein the processor is configured to multiply for a plurality of positions of the window function along the azimuth.

4. The apparatus of claim 1, wherein the processor is configured to:

create a received power azimuth bin array;

calculate a window function from the antenna beam response pattern;

calculate at least one product function by multiplying the received power azimuth bin function by the window function;

calculate an estimated azimuth bin offset based on the mean of the product function;

calculate an azimuth position of an estimated target location based on the azimuth bin offset; and

add a reflected power value corresponding to the integral of the product function to an element of the reconstructed azimuth bin array corresponding to the estimated target location, thereby enhancing the resolution of the map image developed from the received radar signal.

5. The apparatus of claim 4, wherein the processor is further configured to calculate a plurality of product functions for a plurality of positions of the window function along the azimuth, the individual product functions corresponding to individual window function positions.

6. The apparatus of claim 5, wherein the processor is further configured to add at least one reflected power value to at least one value stored in an element of the reconstructed azimuth bin array, whereby the element of the reconstructed azimuth bin array corresponds to the azimuth position of the estimated target location.

7. The apparatus of claim 6, wherein the processor is further configured to substitute a pattern of values stored in the reconstructed azimuth bin array for the received power azimuth bin array, whereby the resolution of the map image becomes enhanced.

8. The apparatus of claim 4, wherein the processor is further configured to calculate the estimated azimuth bin offset by subtracting the azimuth position at the window function mean from the azimuth position at the product function mean, multiplying by two and rounding to the nearest integer.

9. The apparatus of claim 4, wherein the processor is further configured to calculate the estimated target location by adding the azimuth bin offset to the azimuth position of the window function mean.

10. A method for acquiring and displaying a radar map image, the method comprising:

pointing a radar antenna in a first direction along an azimuth;

receiving at the radar antenna a reflected radar signal when pointed at the first direction along the azimuth;

repeating the steps of pointing and receiving for a plurality of predefined directions along the azimuth;

converting the plurality of received radar signals into a bin array of received power versus azimuth,

generating a map image from the bin array of received power versus azimuth using a pre-defined window function; and

displaying the map image on a map display.

11. The method of claim 10, wherein generating a map image comprises:

creating an azimuth bin array;

calculating a window function from the antenna beam response pattern;

calculating at least one product function by multiplying the received power azimuth bin array by the window function;

calculating an estimated azimuth bin offset based on the mean of the product function;

calculating the azimuth position of an estimated target location based on the azimuth bin offset; and

adding a reflected power value corresponding to the integral of the product function to an element of a reconstructed azimuth bin array corresponding to the estimated target location, thereby enhancing the resolution of the map image generated from the received radar signal.

12. The method of claim 11, wherein calculating at least one product function comprises calculating a plurality of product functions for a plurality of positions of the window function along the azimuth, the individual product functions corresponding to individual window function positions.

13. The method of claim 12, wherein adding a reflected power value comprises adding at least one reflected power value to at least one value stored in an element of the reconstructed azimuth bin array, whereby the element of the reconstructed azimuth bin array corresponds to the azimuth position of the estimated target location.

14. The method of claim 13, wherein generating a map image comprises substituting a pattern of values stored in the reconstructed azimuth bin array for the received power azimuth bin array, whereby the resolution of the map image becomes enhanced.

15. The method of claim 11, wherein calculating the estimated azimuth bin offset comprises subtracting the azimuth position at the window function mean from the azimuth position at the product function mean, multiplying by two and rounding to the nearest integer.

16. The method of claim 11, wherein calculating the estimated target location comprises adding the azimuth bin offset to the azimuth position at the window function mean.