Floodlight Radar Sparse Array Ambiguity Resolution
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Solution Overview
Problem
Conventional floodlight radar systems face challenges in accurately detecting and locating fast-moving targets in three dimensions due to issues with grating lobes, angular ambiguities, and high hardware costs, particularly with sparse interferometer arrays, which require increased transmitter power and complex ambiguity resolution methods.
Innovation Solution
A floodlight radar system utilizing a sparse array of receive antennas arranged in a common plane, generating output waveforms at two centre frequencies to resolve ambiguities through Doppler spectra and phase differences, allowing for accurate calculation of target position, velocity, and angular location using a signal processor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sparse interferometer receive array is used, then hardware count is reduced, but angular ambiguities occur where targets at different locations produce similar antenna responses
Solution Approach 1:
The patent applies parameter changes by using multiple center frequencies (frequency diversity) to resolve angular ambiguities. The signal processor compares phase differences and Doppler spectra at different frequencies to distinguish between targets at different locations that produce similar responses at a single frequency, thereby maintaining measurement precision while using a sparse array configuration
Solution Approach 2:
The patent uses Doppler spectra as an intermediary to resolve angular ambiguities. By analyzing the relationship between calculated Doppler spectra, wavelengths, and phase differences at multiple frequencies, the system can disambiguate target locations that would otherwise be indistinguishable with a sparse array
2Measurement precision
If a densely packed phased array is used, then simultaneous beams covering the full search volume can be formed with high antenna gain, but the system becomes complex and costly
Solution Approach 1:
The patent uses a sparse array configuration that requires fewer antennas and less complex hardware compared to densely packed arrays. While individual antenna elements may need to be more sophisticated to compensate for the sparse geometry, the overall system uses fewer components, reducing complexity and cost while maintaining adequate performance through signal processing techniques
3Device complexity
If a sparse array with wide-beam radiators is used, then hardware requirements are reduced, but directivity and gain are much lower requiring increased transmitter power
Solution Approach 1:
The patent merges the advantages of sparse array configurations with multi-frequency operation. By combining signals from multiple frequencies and using sophisticated signal processing to resolve ambiguities, the system maintains adequate gain and directivity without requiring the high transmitter power that would otherwise be needed to compensate for the sparse, low-directivity antenna configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively detects and locates targets in three dimensions with reduced hardware requirements, resolving angular ambiguities and providing reliable measurements by employing frequency diversity, while maintaining high accuracy and detecting fast-moving targets within a large search volume.
Implementation Method 1
a transmitter arranged to generate output waveforms at first and second centre frequencies
Implementation Method 2
resolve ambiguities in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences
Data Source
AI summary
A floodlight radar system includes a transmitter arranged to generate output waveforms at first and second centre frequencies, and at least one transmit antenna configured to illuminate a search volume constantly at the first and second centre frequencies. A sparse array of receive antennas is arranged in a common plane and configured to monitor the search volume constantly. The system includes a receive circuit arranged to extract target position information from return signals received by each antenna, and a signal processor circuit which is arranged to resolve ambiguity in the position information using a known relationship between calculated Doppler spectra, wavelengths and phase differences at the first and second frequencies, to calculate azimuth, elevation, range and velocity of a target identified in the search volume. The system is able to rapidly detect and locate multiple fast moving targets in three dimensions.