3-D weather for digital radar landmass simulation

• US 5,135,397 A
• Filed: 06/28/1990
• Issued: 08/04/1992
• Est. Priority Date: 06/28/1990
• Status: Expired due to Term

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Yen, Craig S.
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/545,213
• Time in Patent Office: 768 Days
• Field of Search: 434/2, 342/26, 364/578
• US Class Current: 434/2
• CPC Class Codes: G01W 1/10 Devices for predicting weather conditions computers per se G06; display devices G09
• CPC Class Codes: G09B 9/40 Simulation of airborne radar
• CPC Class Codes: G09B 9/54 Simulation of radar G09B9/40 takes precedence

Abstract

Weather simulation is a modular addition to a digital radar landmass simulator (DRLMS). The DRLMS is a four channel system, i.e., culture, elevation, aspect and weather. All four channels are integrated to provide a simulated radar landmass simulation with weather. Implementation entails the full or partial occultation of terrain and targets by weather and vice versa. Weather mass is simulated in three dimensions; that is, it has a bottom and height. The weather mass is not made of simple geometric objects. Weather maps can be loaded into the system as weather patterns, and the weather patterns can be expanded, rotated and translated. In addition, the weather channel can be used to simulate chaff and jamming patterns.

Claims

1. A method of real time three-dimensional weather generation in digital radar landmass simulation comprising the steps of:

compressing off line digital weather data as a compressed weather data base for the simulation;

storing the compressed weather data in a database for later access and reconstruction for the simulation;

synchronously ad continuously accessing the compressed weather data from said database and reconstructing and temporarily storing the data;

inputting weather top, weather bottom and depression angle data;

inputting weather expansion, rotation and translation data;

computing weather expansion, rotation and translation as ownship approaches a weather mass in a weather simulation;

computing from said weather top, weather bottom and depression angle data and from the computed weather expansion, rotation and translation a modified attenuation distance; and

processing the temporarily stored weather data with said modified attenuation distance to produce a real time simulation of weather.

2. The method of real time weather generation recited in claim 1 wherein said step of inputting weather top and weather bottom data is performed using weather reflectivity maps.

3. The method of real time weather generation recited in claim 2 wherein said weather reflectivity maps are used to compute both a modified attenuation distance and, in addition, backscattering due to weather.

4. The method of real time weather generation recited in claim 1 further comprising the steps of:

inputting position and reflectivity data for chaff; and

computing radar jamming.

5. A modularized digital radar land mass simulator comprising:

means for compressing off line digital aspect, elevation, reflectivity and weather data as compressed data for the simulation;

means for storing the compressed data in a database for later access and reconstruction;

first, second and third channels for accessing said compressed data in said database and reconstructing and storing respectively aspect, elevation and reflectivity data and synchronously and continuously retrieving said data in real time;

means for generating scan and depression angles and computing radar incident vectors;

aspect computer means connected to said first channel for generating radar aspect returns;

shadowing and converter means connected to said second channel for calculating shadowing due to elevation and slant range as a function of ground range;

radar equation means connected to said third channel and said aspect computer means and said shadowing and converter means for calculating a simulated radar image;

display means connected to said radar equation means for displaying a simulated radar image;

a fourth channel for accessing said compressed data in said database and reconstructing and storing weather data and synchronously and continuously retrieving said weather data in real time, said fourth channel including;

data input means for temporarily storing cloud top data, cloud bottom data, weather expansion, rotation and translation data, depression angle of a simulated radar antenna pattern, terrain height and ownship height;

detecting means responsive to data temporarily stored in said data input means for detecting the respective relative positions of ownship and terrain with respect to clouds; and

computing means responsive to said detecting means for selecting data from said data input means for computing a modified attenuation distance between ownship and terrain due to weather effects, said computing means computing weather expansion, rotation and translation as ownship approaches a weather mass in a weather simulation;

said radar equation means being responsive to said modified attenuation distance for modifying said simulated radar image to account for weather effects in real time.

6. The modularized digital radar land mass simulator as recited in claim 5 further including weather map means for storing weather maps from which are input said cloud top and cloud bottom data.

7. The modularized digital radar land mass simulator as recited in claim 6 wherein said weather maps are used by said means for computing to compute both said modified attenuation distance and backscattering due to weather.

8. The modularized digital radar land mass simulator as recited in claim 5 wherein said data input means also temporarily stores chaff distance and reflectivity data, said means for computing additionally computing radar jamming.

9. A real-time three-dimensional, high-resolution weather channel for a modular digital radar land mass simulator comprising:

means for compressing off line digital weather data as a compressed weather database for the simulation;

storage and data retrieval means for accessing said database and reconstructing and storing weather data and synchronously and continuously retrieving said weather data in a real time;

data input means connected to said storage and data retrieval means for temporarily storing cloud top data, cloud bottom data, weather expansion, rotation and translation data, depression angle of a simulated radar antenna pattern, terrain height and ownship height;

detecting means responsive to data temporarily stored in said data input means for detecting the respective relative positions of ownship and terrain with respect to clouds; and

computing means responsive to said detecting means for selecting data from said data input means for computing in real time weather expansion, rotation and translation as ownship approaches a weather mass in a weather simulation, said computing means computing from said weather top, weather bottom and depression angle data and from the computed weather expansion, rotation and translation a modified attenuation distance between ownship and terrain due to weather effects.

10. The weather channel recited in claim 9 further including weather map means for storing weather maps from which are input said cloud top and cloud bottom data.

11. The weather channel recited in claim 10 wherein said weather maps are used by said means for computing to compute both said modified attenuation distance and backscattering due to weather.

12. The weather channel recited in claim 9 wherein said data input means also temporarily stores chaff distance and reflectivity data, said means for computing additionally computing radar jamming.