Radar Signal Processing Using Time Scale Factor
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Solution Overview
Problem
Existing radar systems struggle to accurately determine the position and velocity of targets over a wide range of bandwidths, as conventional methods are primarily effective only in narrowband applications and require extensive modifications to existing equipment, making them impractical for use in wider bandwidth scenarios.
Innovation Solution
A method of signal processing that uses a modified Cross Ambiguity Function (CAF) technique, where signals are modeled as a change of scale, allowing for the calculation of radial velocity and range by setting appropriate variables and performing discrete Fourier transforms to estimate maximum values, applicable to both single and multiple signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CAF process is used with fixed stable carrier frequency or fixed stable pulse repetition frequency, then velocity estimation can be obtained, but measurement precision deteriorates when signal is not a single sine wave
Solution Approach 1:
The patent changes the fundamental parameter of how Doppler is modeled from frequency translation to time-axis scale change. This parameter change allows the CAF process to accurately handle non-sinusoidal signals while maintaining velocity estimation accuracy, resolving the contradiction between measurement precision and signal type compatibility.
Solution Approach 2:
Instead of modeling Doppler as a frequency shift (conventional approach), the patent inverts the model to treat Doppler as a time-axis scaling effect. This inversion enables accurate processing of non-sinusoidal signals by focusing on the temporal compression/expansion characteristic of Doppler rather than frequency translation.
2Measurement precision
If narrowband signal processing methods are used, then existing radar equipment can be used, but measurement precision deteriorates for wideband signals
Solution Approach 1:
The patent creates a universal CAF processing method that works for both narrowband and wideband signals using the same time-axis scaling model. This multi-functionality allows existing radar equipment to accurately process wideband signals without requiring separate specialized systems, thereby improving measurement precision without proportionally increasing device complexity.
Solution Approach 2:
By changing the Doppler modeling parameter from frequency translation to time-axis scale change, the patent enables a single processing framework to handle various signal bandwidths accurately. This parameter change eliminates the need for bandwidth-specific processing chains, improving precision for wideband signals while avoiding extensive equipment modifications.
3Measurement precision
If fractional Fourier transform is used in CAF to track objects, then position and velocity estimation is improved, but device complexity increases
Solution Approach 1:
The patent segments the Doppler effect into discrete time-axis scaling operations that can be processed through standard FFT algorithms. By breaking down the complex fractional Fourier transform requirements into simpler scaling and transformation steps, the method achieves improved position and velocity estimation while keeping computational complexity manageable through efficient algorithm implementation.
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
This approach enables accurate determination of target position and velocity across a wide range of bandwidths, improving accuracy and practicality by avoiding the need for costly equipment modifications, thus enhancing geolocation capabilities in radar systems.
Implementation Method 1
Doppler is a familiar phenomenon in which the frequency of a received signal appears to change as the radial velocity between the transmitter and receiver changes. Historically, this change in frequency has been modeled as a translation in frequency, but, as we will show, this model is not correct. The correct model is that Doppler results in a change of scale of the time axis of the signal.
Data Source
AI summary
The present invention is a method of finding range and velocity of a target in a radar system using a time scale factor. Specifically, sending at least one signal from at least one transmitter to a target. A return signal is then received from the target at each transmitter and the elapsed time is recorded. The range to the target and velocity of the target are calculated based on a time scale factor of the recorded elapsed times. These values are appropriately output to the user.