Radar Velocity Calculation Using Multi-PRF Folding Correction
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Solution Overview
Problem
Radar devices face limitations in accurately calculating high target velocities due to 'folding' effects, where calculated velocities are lower than actual, especially when the Doppler frequency exceeds the pulse repetition frequency, making it difficult to determine accurate velocities for targets with high velocities.
Innovation Solution
A radar device and method that transmit pulse signals at two or more different pulse repetition frequencies, using multiple calculators and correctors to calculate and correct Doppler velocities by determining the number of folds and phase differences, allowing for more accurate velocity calculations through folding correction and averaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse signals are transmitted at a single pulse repetition frequency, then the device complexity is low, but the measurement precision of high velocity targets deteriorates due to folding effects
Solution Approach 1:
The patent applies periodic action by transmitting pulse signals at multiple different pulse repetition frequencies (PRF) in an alternating manner. This periodic variation in PRF allows the system to capture Doppler velocities at different sampling rates, enabling the detection of high-velocity targets without folding effects while maintaining manageable system complexity through structured temporal multiplexing.
Solution Approach 2:
The patent changes the parameter of pulse repetition frequency by using at least two different PRF values (e.g., first PRF and second PRF) for transmitting pulse signals. This parameter variation allows the system to overcome the folding limitation at high velocities by capturing velocity information at different PRF levels, thereby improving measurement precision without requiring a fundamentally complex system architecture.
2Measurement precision
If folding correction is performed using a single pulse repetition frequency, then the velocity calculation accuracy improves, but the reliability of velocity measurement deteriorates due to ambiguity in determining the number of folds
Solution Approach 1:
The patent implements feedback by using the velocity information obtained at one PRF to guide the folding correction process for velocities measured at another PRF. The system continuously refines the velocity measurements by comparing results across different PRF settings and using this feedback to determine the correct number of folds, thereby simultaneously improving both accuracy and reliability of velocity measurements.
Solution Approach 2:
The patent applies preliminary action by performing folding correction based on velocity differences obtained at different pulse repetition frequencies before finalizing the velocity measurement. By preliminarily determining the number of folds using multiple PRF measurements, the system establishes a more robust foundation for accurate velocity calculation, reducing ambiguity and improving measurement reliability.
3Measurement precision
If multiple pulse repetition frequencies are used, then the velocity measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent uses periodic action by implementing an alternating transmission scheme where pulse signals are sent at different PRF values in a structured temporal pattern. This approach allows multiple velocity measurements to be obtained through time-multiplexed PRF variation rather than requiring parallel transmission systems, thereby improving precision while keeping the transmitter and processor complexity manageable through sequential operation.
Solution Approach 2:
The patent applies universality by designing a single radar system that can operate at multiple pulse repetition frequencies and perform both high-velocity and low-velocity measurements using the same hardware architecture. The system uses a universal processing approach where the same transmitter and processor handle different PRF settings and velocity ranges, avoiding the need for separate specialized systems and thus limiting the increase in device complexity.
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 more accurate Doppler velocity calculations by correcting for folding effects, resulting in higher precision and reduced variance in measured velocities compared to previous methods.
Implementation Method 1
A radar device for detecting the velocity of a target, such as rain or clouds, transmits a plurality of pulse signals and calculates the velocity from the amount of phase rotation of an echo signal reflected by the target
Implementation Method 2
echo signal reflected by the target
Data Source
AI summary
It is an object of the present invention to provide a radar device and a velocity calculation method with which velocity can be calculated more accurately. A radar device 1 comprises a transmitter 23, a first velocity calculator 31a, a second velocity calculator 31b, a first velocity corrector 33a, and a second velocity corrector 33b. The transmitter 23 transmits pulse signals at two or more different pulse repetition frequencies. The first velocity calculator 31a calculates a first Doppler velocity based on a first received signal. The second velocity calculator 31b calculates a second Doppler velocity based on a second received signal. The first velocity corrector 33a calculates a first corrected Doppler velocity by folding correction of the first Doppler velocity. The second velocity corrector 33b calculates a second corrected Doppler velocity by folding correction of the second Doppler velocity.