Coded Aperture Radar Noise Reduction via Multibit Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coded Aperture Radar (CAR) systems face ambiguity issues due to multiplicative noise, which limits their sensitivity and dynamic range, especially in Type I CAR systems, leading to reduced effectiveness in acquiring 3D location and radial velocity information within a short acquisition period.
Innovation Solution
The implementation of additional measurements in CAR coding schemes, using an array of N antenna elements with single bit modulators and a sequence of multibit codes, allows for the reduction of ambiguity by determining element signals and forming effective beams with specific sidelobe characteristics, thereby enhancing sensitivity and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If Type I CAR coding scheme is used to achieve short acquisition period, then acquisition time is reduced, but sensitivity and dynamic range deteriorate due to multiplicative noise
Solution Approach 1:
The patent segments the aperture coding into multiple measurement sets, where each set contains multiple codes. By dividing the coding sequence into structured segments with specific mathematical relationships, the system achieves both short acquisition time and reduced multiplicative noise through the segmented measurement approach
Solution Approach 2:
The patent changes the coding parameters by using multibit codes instead of simple binary codes, and structures the codes in specific mathematical relationships (orthogonal, complementary, or dual-complementary). This parameter change transforms the multiplicative noise characteristics while maintaining short acquisition period
2Reliability
If additional measurements are implemented to reduce ambiguity, then sensitivity and dynamic range improve, but device complexity increases
Solution Approach 1:
The patent designs a universal coding framework that can accommodate different code types (orthogonal, complementary, dual-complementary) within a single measurement structure. This multi-functional approach allows the system to achieve reduced ambiguity through additional measurements while maintaining manageable complexity through a unified processing methodology
3Productivity
If Type I CAR is used for short range applications, then acquisition period is short, but ambiguity reduces effectiveness in acquiring 3D location and velocity information
Solution Approach 1:
The patent incorporates feedback mechanisms where the measured signals from multiple codes and measurement sets are processed to iteratively reduce ambiguity. The system uses the collected measurement data to refine the estimation of 3D location and velocity information, ensuring complete and accurate target characterization while maintaining short acquisition period
Data Source
AI summary
A method and apparatus for reducing noise in a coded aperture radar system, the coded aperture radar system transmitting signals which occur in sweeps, with K sweeps utilized to cover field of view of the coded aperture radar system and Q frequency shifts or steps occurring each sweep thereof. An array of N antenna elements is provided, the array of antenna elements each having an associated two state modulator coupled therewith. Energy received at the array is modulated according to a sequence of multibit codes, the number of codes in the sequence of codes comprising at least K times Q times N, thereby reducing noise in the coded aperture radar system compared to a coded aperture radar system radar system having fewer than K times Q times N codes in its sequence of multibit codes.