Methods and apparatus for terrain correlation

• US 6,803,878 B2
• Filed: 05/13/2002
• Issued: 10/12/2004
• Est. Priority Date: 05/13/2002
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Oven, James B., Formo, Jason I., Hager, James R.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/144,877
• Publication Number:
  US 20030210180A1
• Time in Patent Office: 883 Days
• Field of Search: 342/118, 342/120, 342/121, 342/122, 342/25, 342/61-65, 342/165-175, 342/190-197, 342/357-1-3, 701/200, 701/207, 701/213-216, 701/223
• US Class Current: 342/173
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/70 for range tracking only
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 13/882 for altimeters measuring height using barometric means G01C5/06
• CPC Class Codes: G01S 13/935 for terrain-avoidance
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/4004 of parts of a radar system

Abstract

A method for testing radar system performance is disclosed which utilizes radar data test points in a radar data file. The method includes interpolating GPS data from a flight test to provide a GPS data point for every radar data test point, generating body coordinate values for every point in a corresponding digital elevation map (DEM) file using the interpolated GPS data, and applying a bounding function around at least a portion of the body coordinate values generated from the DEM file at a given time. The method also includes determining which body coordinate value generated from the DEM file is closest a current GPS data point for the given time and comparing the determined body coordinate value to the radar data test points at the given time.

Claims

1. A method for testing operating capabilities of a radar system, said method comprising:

storing samples of radar data from a flight, the samples comprising body coordinate values;

storing samples of global positioning satellite (GPS) data from the flight;

interpolating the GPS data samples to provide GPS data samples that correspond to every radar data sample;

selecting a plurality of the radar data samples;

generating a simulated radar file of body coordinate values from a digital terrain elevation map file based on interpolated GPS data samples that correspond to the selected radar data samples; and

comparing the body coordinate values from the simulated radar file to the body coordinate values from the corresponding radar data samples.

2. A method according to claim 1 further comprising processing the radar data samples using a low pass filter.

3. A method according to claim 1 further comprising processing the radar data samples using data decimation to reduce a size of the data.

4. A method according to claim 1 wherein interpolating the GPS data samples comprises using a straight line fit to fill in missing data points within the GPS data samples.

5. A method according to claim 1 wherein generating a simulated radar file of body coordinate values comprises:

applying a bounding function around at least a portion of the body coordinate values generated from the digital terrain elevation map for a given time; and

determining which body coordinate value generated from the digital terrain elevation map is closest to an interpolated GPS data sample for the given time.

6. A method according to claim 5 wherein applying a bounding function comprises decreasing a number of the body coordinate values generated from the digital terrain elevation map file using at least one bounding value from the radar data samples.

7. A method according to claim 5 wherein a first bounding value is based on a radar antenna angle and aircraft altitude values.

8. A method according to claim 7 wherein a second bounding value is based on a radar swath width value and aircraft altitude values.

9. A computer programmed to:

store a global positioning satellite (GPS) file including GPS data samples, a radar data file including radar data samples, the radar data samples including body coordinate values, each GPS data sample corresponding to one of the radar data samples, and a digital terrain elevation map file;

interpolate the stored GPS data samples to generate a GPS data sample that corresponds to every stored radar data sample;

generate a simulated radar file of body coordinate values from the digital terrain elevation map file based on the interpolated GPS data samples; and

compare the body coordinate values from the simulated radar file to the body coordinate values from the radar data samples.

10. A computer according to claim 9 wherein the GPS data samples include time, latitude, longitude, and altitude, the radar data samples include time, radar data test points in x, y, and z body coordinates and altitude, the radar data samples time synchronized with the GPS data samples, and the digital terrain elevation map file includes latitude, longitude and elevation.

11. A computer according to claim 9 further programmed to process the radar data test points using a low pass filter.

12. A computer according to claim 9 further programmed to process the radar data test points using data decimation.

13. A computer according to claim 9 wherein to interpolate the GPS data samples said computer is programmed to use a straight line fit to generate additional GPS data points.

14. A computer according to claim 9 further programmed to apply abounding function around at least a portion of the generated body coordinate values from the simulated radar file.

15. A computer according to claim 14 wherein to apply the bounding function said computer is programmed to decrease a number of the body coordinate values generated from the digital terrain elevation map file to be compared using at least one bounding value from the radar data samples.

16. A computer according to claim 15 programmed to calculate a first bounding value based on a radar antenna angle and aircraft altitude value.

17. A computer according to claim 16 programmed to calculate a second bounding value based on a radar swath width value and aircraft altitude values.

18. A computer according to claim 9 wherein to generate a simulated radar file of body coordinate values from the digital terrain elevation map file said computer is programmed to generate body coordinate values for every data point in the digital terrain elevation map file using the interpolated GPS data samples.

19. A computer program embodied on a computer readable medium for testing operating capabilities of a radar system, comprising:

a data storage source code segment for storing a global positioning satellite (GPS) file including GPS data samples, storing a radar data file including radar data samples, the radar data samples including body coordinate values, each GPS data sample corresponding to one of the radar data samples, and storing a digital terrain elevation map file;

an interpolation source code segment for interpolating the stored GPS data samples to generate a GPS data sample that corresponds to every stored radar data sample;

a file generation source code segment for generating a simulated radar file of body coordinate values from the digital terrain elevation map file based on the interpolated GPS data samples; and

a comparison source code segment for comparing the body coordinate values from the simulated radar file to the body coordinate values from the radar data samples.