Piecewise Hyperbolic Waveform for CDMA Radar Cross-Correlation

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Solution Overview

Problem

Existing CDMA radar systems face limitations in distinguishing multiple objects due to limited dynamic range and cross-correlation properties, particularly when using conventional coding families like Gold or Hadamard, which restricts the ability to separate reflections from multiple transmit signals in the field of view.

Innovation Solution

A piecewise hyperbolic waveform is generated with each codeword consisting of three segments: two linear frequency modulation (LFM) segments and one hyperbolic frequency modulation (HFM) segment, transmitted simultaneously using multiple antenna elements, ensuring orthogonality and improved cross-correlation properties by varying segment durations and bandwidths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional coding families (Gold or Hadamard) are used in CDMA radar systems, then the system can operate with standard waveforms, but the dynamic range is limited and cross-correlation properties are insufficient for distinguishing multiple objects

Engineering Contradiction:

Improveobject distinction capabilityVSAvoidcross-correlation properties

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The waveform is divided into three distinct segments: two LFM segments and one HFM segment in the middle. This segmentation allows each segment to serve a specific function in improving both auto-correlation and cross-correlation properties, enabling better distinction between multiple objects while maintaining reliable detection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the frequency modulation parameters by introducing hyperbolic frequency modulation (HFM) in the middle segment, which has different correlation properties compared to conventional LFM. This parameter change improves cross-correlation performance and dynamic range, allowing reliable distinction of multiple objects

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple transmit antenna elements are used simultaneously, then the system can improve detection capability, but the reflections from various transmissions become difficult to distinguish without proper transmission schemes

Engineering Contradiction:

Improvereflection separation capabilityVSAvoidtransmission scheme complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Different transmit antenna elements are assigned different codewords from the piecewise hyperbolic family, giving each transmission a unique local characteristic. This allows the receiver to distinguish reflections from different antennas through correlation processing, improving reflection separation capability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses periodic transmission of codewords from the piecewise hyperbolic family, where each codeword is transmitted in sequence or simultaneously from different antennas. This periodic structure enables the receiver to distinguish and process reflections from multiple transmit elements through correlation with the known codeword sequence

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11391829B2Piecewise hyperbolic waveform for code division multiple access radar system operation

Publication Date: 2022.07.19 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods and systems involve generating a family of codewords. Each codeword of the family of codewords including three segments with one of the three segments being a hyperbolic frequency modulation (HFM) segment and two of the three segments being linear frequency modulation (LFM) segments. A method includes transmitting each codeword of the family of codewords using a different transmit antenna element.