Radar Doppler Correction Phase Rotation Controller
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Solution Overview
Problem
Current radar devices face challenges in reducing transmission time and increasing the maximum-speed detection range while accurately detecting Doppler frequencies, especially when mounted on moving objects, due to limitations in correcting Doppler frequency shifts and preventing aliasing.
Innovation Solution
The radar device incorporates a doppler correction phase-rotation controller to pre-correct Doppler frequency components based on the movement speed of the object, using pulse compression codes and phase rotation to transmit corrected signals, and performs Doppler-frequency analysis to calculate position-determination results, thereby extending the detection range without increasing transmission time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FFT processing is used to detect Doppler frequency, then calculation amount is reduced and detection efficiency is improved, but Doppler frequency aliasing occurs when reception pulses include Doppler frequency components that exceed the sampling theorem
Solution Approach 1:
The patent applies preliminary action by performing phase rotation processing on the received signal before FFT processing to pre-correct the Doppler frequency shift caused by the moving object's own motion. This preliminary correction ensures that the subsequent FFT processing operates on signals with reduced Doppler frequency components, preventing aliasing while maintaining computational efficiency.
2Measurement precision
If the stagger system is used to detect and correct aliasing components of Doppler frequency, then the maximum-speed detection range is increased, but the transmission time is doubled
Solution Approach 1:
The patent performs preliminary phase rotation correction using the moving object's speed information before the main detection process, which prevents aliasing from occurring in the first place. This eliminates the need for the stagger system's dual-PRI approach and associated transmission time doubling, while still achieving extended maximum-speed detection range through the phase rotation pre-correction.
3Adaptability or versatility
If a radar device is mounted on a moving object, then the radar can detect targets while the object is in motion, but Doppler frequency shifts are affected by the movement speed of the moving object
Solution Approach 1:
The patent employs feedback by using the detected Doppler frequency information and the known moving object speed to calculate and apply a phase rotation correction factor. This feedback loop continuously compensates for the Doppler frequency shifts caused by the moving object's motion, maintaining measurement accuracy despite the radar's mobility.
Solution Approach 2:
The patent introduces phase rotation processing as an intermediary step between signal reception and FFT processing. This intermediary operation corrects the Doppler frequency shift caused by the moving object's motion, acting as a mediator that separates the effect of the platform's motion from the target's motion, thereby preserving measurement accuracy.
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 solution effectively corrects Doppler frequency influences from moving objects, enhances detection range, and suppresses the need for additional transmission time, allowing for accurate Doppler frequency detection and position determination across varying speeds.
Implementation Method 1
When at least one of a target and a radar device moves, a radar reflection wave is affected by a Doppler frequency shift corresponding to an amount proportional to a relative speed between the target and the radar device. Thus, by detecting a Doppler frequency of the target, the radar device can calculate the relative speed between the target and the radar device.
Implementation Method 2
a phase rotator, which in operation, corrects the radar transmission signal for each radar transmission interval Tr, based on the Doppler correction phase-rotation amount
Data Source
AI summary
A radar device is mounted on a vehicle, which is a moving object, and includes a doppler correction phase-rotation controller and a phase rotator. Based on the speed of the vehicle, the doppler correction phase-rotation controller calculates a Doppler correction phase-rotation amount for correcting a Doppler frequency due to movement of the vehicle. By using the Doppler correction phase-rotation amount, the phase rotator pre-corrects Doppler frequency components with respect to a radar transmission signal in each transmission interval of the radar transmission signal.