Radar Speed Ambiguity Resolution via Dual Processing Units
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Solution Overview
Problem
Radar apparatuses face challenges in reducing speed ambiguity caused by phase folding back without increasing sampling speed, which is costly and difficult to implement in on-board systems.
Innovation Solution
A radar apparatus with a first processing unit determining speed from phase rotation of frequency components and a second processing unit determining speed from Doppler frequency, allowing for high-resolution speed measurement without increasing sampling speed by comparing calculation results from both units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sampling speed is increased to reduce speed ambiguity, then measurement precision is improved, but device cost increases due to requiring higher-speed AD converters
Solution Approach 1:
The patent divides the speed measurement function into two separate processing units: a first processing unit that determines speed with high resolution but includes ambiguity, and a second processing unit that determines speed without ambiguity. By segmenting the measurement function and combining results, the system achieves unambiguous high-resolution speed measurement without requiring high-speed AD converters.
Solution Approach 2:
The patent introduces a speed determining unit as an intermediary that compares calculation results from both processing units. This intermediary component resolves the ambiguity by selecting the appropriate speed value based on the comparison, enabling accurate speed measurement without direct high-speed sampling.
2Measurement precision
If chirp duration is shortened to reduce speed ambiguity, then speed measurement range is improved, but the number of samplings required decreases making frequency analysis difficult
Solution Approach 1:
The patent segments the speed measurement approach into two different processing methods using the same beat signal: one that provides high resolution through phase rotation analysis and another that provides unambiguous speed through Doppler frequency analysis. This segmentation allows the system to maintain adequate sampling rates while achieving both high resolution and unambiguous speed measurement.
3Measurement precision
If phase rotation method is used to determine speed, then resolution is improved, but ambiguity caused by phase folding back occurs
Solution Approach 1:
The patent merges the results from two different speed determination methods: the first processing unit provides high-resolution speed measurement through phase rotation, while the second processing unit provides unambiguous speed measurement through Doppler frequency analysis. By combining these complementary approaches, the system achieves both high resolution and reliability without the ambiguity of phase folding back.
Solution Approach 2:
The speed determining unit uses feedback by comparing the calculation results from both processing units. When the first processing unit's result shows ambiguity, the system uses the second processing unit's unambiguous result to resolve it, creating a feedback mechanism that ensures reliable speed determination while maintaining high resolution.
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
Resolves speed ambiguity and improves reliability of speed detection in radar apparatuses without requiring high-speed AD converters, enabling cost-effective high-resolution speed measurement.
Implementation Method 1
A radar apparatus uses a chirp wave of which the frequency continuously increases or decreases
Implementation Method 2
determines at least speed that is uniquely determined within the speed measurement range, from Doppler frequency included in frequency components indicating a target
Data Source
AI summary
A radar apparatus includes a first processing unit, a second processing unit, and a speed determining unit. Of these units, the first processing unit determines at least speed including ambiguity caused by phase folding back within a predetermined speed measurement range, from phase rotation of frequency components detected in time-series for a same target, using a beat signal obtained by transmitting and receiving, a plurality of times, a predetermined first modulation wave. The second processing unit determines at least speed that is uniquely determined within the speed measurement range, from Doppler frequency included in frequency components indicating a target, using a beat signal obtained by transmitting and receiving a predetermined second modulation wave. The speed determining unit determines a measurement result for speed expressed by a resolution obtained by the first processing unit by comparing a calculation result of the first processing unit and a calculation result of the second processing unit.