Radar Apparatus With Delayed Doppler Multiplexing for Low-Velocity Detection
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Solution Overview
Problem
Existing radar systems face challenges in accurately sensing target objects due to ambiguity in Doppler frequency detection, particularly for lower relative velocities, which limits their sensing accuracy and range.
Innovation Solution
A radar apparatus employing Doppler multiplexing transmission, where phase rotation amounts corresponding to Doppler shift amounts and code sequences are applied to transmission signals, allowing simultaneous multiplexing and transmission from multiple antennas, with controlled transmission delays and orthogonal coding to enhance separation and detection in the Doppler frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler frequency detection is performed using conventional radar methods, then detection capability is achieved, but ambiguity occurs in Doppler frequency detection particularly for lower relative velocities
Solution Approach 1:
The invention segments the Doppler frequency detection range by introducing multiple transmission delays (first transmission delay and second transmission delay) that are different from each other. This segmentation allows the radar to distinguish between different Doppler frequency ranges that would otherwise be ambiguous, particularly resolving the detection ambiguity for lower relative velocities by separating them into distinct detection bins through the delay-based frequency shift.
Solution Approach 2:
The invention adds a time delay dimension to the conventional Doppler frequency detection. By applying different transmission delays to different transmission signals, the system creates an additional degree of freedom in the frequency domain. This dimensional extension allows the radar to resolve ambiguities by detecting not just the Doppler frequency itself but also the delay-induced frequency shift, thereby improving measurement precision for lower relative velocities.
2Adaptability or versatility
If the range of Doppler frequencies is extended to detect objects over wider frequency range, then detection range is improved, but aliasing occurs in Doppler frequency detection
Solution Approach 1:
The invention segments the extended Doppler frequency range into multiple non-overlapping detection regions by using different transmission delays. Each transmission delay creates a distinct frequency shift pattern that maps to a specific Doppler frequency range. This segmentation prevents aliasing by ensuring that signals from different velocity ranges fall into separate detection bins, thereby maintaining measurement precision while extending the overall detection range.
Solution Approach 2:
The transmission delay acts as an intermediary that mediates between the extended Doppler frequency range and the detection system. By introducing controlled time delays before transmission, the system creates intermediate frequency shifts that prevent direct aliasing between high and low velocity signals. This intermediary mechanism allows the radar to detect objects across a wider frequency range without sacrificing detection accuracy.
3Area of stationary object
If multiple transmission antennas are used for multiplexing transmission, then sensing coverage is improved, but signal separation and detection becomes more difficult
Solution Approach 1:
The invention applies preliminary action by pre-modulating each transmission signal with a specific transmission delay before multiplexed transmission from multiple antennas. This preliminary imposition of distinct time delays creates unique frequency shift signatures for each antenna's signal. When signals are received and processed, these pre-established delay differences enable straightforward separation and detection of individual antenna contributions, reducing the difficulty of signal processing while maintaining expanded sensing coverage.
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 extends the range of Doppler frequencies without aliasing, improving target-object sensing accuracy and resolving ambiguities, thereby enhancing the radar's ability to detect objects over a wider frequency range.
Implementation Method 1
a transmission circuit that applies a phase rotation amount corresponding to a Doppler shift amount and a code sequence to the transmission signal to perform multiplexing transmission of the transmission signal from the plurality of transmission antennas
Implementation Method 2
a radar apparatus with an enhanced sensing accuracy for sensing a target object
Data Source
AI summary
The radar apparatus includes: a plurality of transmission antennas that transmit a transmission signal; and a transmission circuit that applies a phase rotation amount corresponding to a Doppler shift amount and a code sequence to the transmission signal to perform multiplexing transmission of the transmission signal from the plurality of transmission antennas. A transmission delay of the transmission signal is set for a transmission period of the transmission signal. Each of the plurality of transmission antennas is associated with a combination of the Doppler shift amount and the code sequence such that at least one of the Doppler shift amount and the code sequence is different between a plurality of the combinations. A number of multiplexing by the code sequence corresponding to a first Doppler shift amount is different from a number of multiplexing by the code sequence corresponding to a second Doppler shift amount.