Radar Phase Compensation via Disparate PRF Segmentation
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Solution Overview
Problem
Radar systems face challenges in compensating for mismatched phase delays caused by target motion, particularly in Time Division Multiplexing (TDM) and Doppler Division Multiplexing (DDM) MIMO operations, leading to phase offset errors that complicate positional characterization of targets.
Innovation Solution
The use of disparate pulse repetition frequencies (PRFs) for respective groups of chirps in radar signals allows for phase compensation and ambiguity resolution in range-Doppler detection, enabling accurate Doppler estimates and positional characterization of moving targets by applying phase compensation to motion-induced phase biases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time Division Multiplexing (TDM) or Doppler Division Multiplexing (DDM) is used for MIMO radar operations, then angular resolution and multiplexing capability are improved, but phase offset errors occur due to target motion between transmission periods
Solution Approach 1:
The patent segments the MIMO transmission into multiple TDM groups, where each group uses a unique Pulse Repetition Frequency (PRF). This segmentation allows the system to maintain the angular resolution benefits of MIMO while resolving phase ambiguities through frequency diversity across the segmented groups
Solution Approach 2:
The patent changes the PRF parameter across different TDM groups to resolve phase offset errors. By assigning unique PRFs to different transmitter antennas or TDM groups, the system can disambiguate phase delays caused by target motion and accurately characterize target position
2Productivity
If transmitters operate at different times for MIMO transmission, then spatial multiplexing is achieved, but mismatched phase delays occur due to target movement between transmission periods
Solution Approach 1:
The patent employs periodic TDM transmission patterns where each transmitter antenna transmits in alternating time slots. By structuring the periodic transmission with unique PRFs for different time slots, the system maintains high MIMO transmission efficiency while enabling accurate phase delay measurement through the periodic structure
Solution Approach 2:
The patent introduces unique PRFs as an intermediary parameter that mediates between the time-division multiplexing structure and the phase delay measurement. This intermediary allows the system to decouple the timing requirements of MIMO transmission from the phase accuracy requirements of target characterization
3Measurement precision
If unique pulse repetition frequencies are assigned to respective chirp groups, then phase ambiguities can be resolved and Doppler estimation accuracy is improved, but signal processing complexity increases
Solution Approach 1:
The patent implements feedback mechanisms where the received signals from multiple TDM groups with unique PRFs are processed to resolve phase ambiguities. The system uses the phase information from different PRF groups to feedback and correct Doppler estimates, improving accuracy while managing processing complexity through structured feedback loops
Data Source
AI summary
Aspects of the present disclosure are directed to radar and radar processing. As may be implemented in accordance with one or more embodiments involving multi-input multi-output (MIMO) co-prime radar signals transmitted by a plurality of transmitters and reflected from at least one target, the reflected radar signals are processed by resolving ambiguities associated with a range-Doppler detection based on unique pulse repetition frequencies (PRF)s associated with respective chirp groups of the reflected radar signals. Phase compensation is applied to compensate for motion-induced phased biases and, thereafter, Doppler estimates are reconstructed to provide a dealiased version of the reflected radar signals.