Phase Doppler Radar Velocity Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Doppler radars face limitations in detecting low-speed targets among static clutter, target ranging, tracking association, and target recognition due to imprecise velocity measurements and inability to accommodate variable inter-pulse period radar architectures.
Innovation Solution
A phase Doppler radar system that utilizes raw in-phase and quadrature data from radar pulses to measure target velocity with high precision, employing a track-before-detect architecture and non-linear least squares fitting to improve detection, ranging, and recognition capabilities without requiring specialized hardware or large bandwidth, and can be deployed as a sidecar subsystem on traditional pulse Doppler radars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Fourier transforms are used to estimate velocity in Doppler radars, then the system can process radar data using standard methods, but the velocity measurement precision is limited by Nyquist and sampling limits
Solution Approach 1:
The patent changes the fundamental parameter of velocity estimation from frequency-domain Fourier analysis to time-domain phase difference analysis. By measuring the phase difference between consecutive pulse returns and converting it directly to velocity using the relationship v = (c * Δφ) / (4π * B), the system achieves precision beyond Nyquist limits without requiring complex specialized processing algorithms
Solution Approach 2:
The patent replaces the conventional Fourier transform mechanical process (frequency domain analysis requiring multiple pulses and complex computation) with a direct phase difference measurement approach. This substitution uses raw in-phase and quadrature data from consecutive pulses to compute velocity directly, eliminating the need for Fourier transform operations and achieving higher precision with simpler processing
2Reliability
If conventional Doppler radar methods are used, then the system can operate with standard radar waveforms, but the detection of low speed targets among static clutter is deficient
Solution Approach 1:
The patent extracts and exploits the phase information from raw in-phase and quadrature data that is typically discarded or underutilized in conventional Doppler processing. By taking out and analyzing the phase component specifically, the system can detect velocity changes as small as a few millimeters per second, enabling reliable detection of low-speed targets that are invisible to conventional methods
Solution Approach 2:
The patent performs preliminary phase measurement and velocity estimation using the phase difference method before conventional detection thresholds are applied. This preliminary action using phase information allows the system to identify potential low-speed targets early in the processing chain, enabling subsequent focused analysis and improving overall detection reliability
3Measurement precision
If conventional Doppler radar techniques are used, then the system can maintain simple architecture, but the target ranging capability is limited
Solution Approach 1:
The patent makes the phase measurement subsystem universal by designing it to work with any traditional pulse Doppler radar waveform and architecture. The same phase difference processing that provides high-precision velocity measurement also provides improved ranging capability through the relationship between phase, velocity, and time, allowing one subsystem to serve multiple functions without adding dedicated ranging hardware
4Measurement precision
If conventional Doppler radar processing is used, then the system can operate with fixed inter-pulse period, but the tracking association is imprecise due to velocity measurement errors
Solution Approach 1:
The patent creates a dynamic processing system that can adapt to variable inter-pulse periods by making the velocity calculation formula flexible. The relationship v = (c * Δφ) / (4π * B) naturally accommodates varying pulse intervals since the phase difference Δφ inherently reflects the actual time baseline between pulses. This dynamic adaptability allows precise tracking association even when pulse repetition intervals change, unlike fixed Fourier-based systems
5Measurement precision
If conventional Doppler radar methods are used, then the system can use standard waveforms, but the target recognition is degraded due to inter-pulse motion
Solution Approach 1:
The patent implements feedback by using the high-precision velocity measurements from phase difference analysis to correct for inter-pulse motion in target recognition processing. The measured velocity information is fed back into the recognition algorithm to compensate for target displacement between pulses, thereby improving recognition accuracy without requiring complex specialized waveforms or additional hardware
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 enhances detection of low-speed targets, improves target ranging and recognition, and is robust to staggered radar pulse data, providing high precision velocity measurements and compatibility with variable inter-pulse period architectures, thus overcoming the limitations of conventional Fourier-based Doppler radars.
Implementation Method 1
collect N consecutive pulses, generated by the pulse Doppler R/T subsystem in response to reflections received from a target
Implementation Method 2
Phase Doppler radar system and method described herein exploit raw in-phase (I) and quadrature (Q) data, derived from a radar pulse returned from a target to measure the velocity of the target
Data Source
AI summary
A phase Doppler radar system may comprise a pulse Doppler receiver/transmitter (R/T) subsystem coupled with a processing subsystem. The system may determine target velocity and target detection events by collecting pulses from the pulse Doppler R/T subsystem, determine an undifferentiated phase of each of the pulses, differentiate the pulses, and determine a differentiated phase of each of the pulses. The system may perform a linear fit of the differentiated phases of the pulses to produce a slope and an intercept. The system may determine a set of initial estimates of coefficients of a nonlinear fit equation. The system may perform iterations of a nonlinear least squares fit, beginning with the initial coefficient estimates, to produce a non-linear fit result. The system may determine a goodness-of-fit (GoF) statistic associated with the nonlinear fit result, and declare a detection event when the GoF is superior to a GoF statistic associated Gaussian noise.