Multistatic Radar Clock Drift Compensation via Timestamp Synchronization
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Solution Overview
Problem
In distributed coherent radar systems, frequency and phase differences between radar systems due to clock signal contamination or variations in local clock sources lead to relative time drift, reducing sensor sensitivity and unambiguous distance measurement capabilities.
Innovation Solution
Determining frequency and initial time offsets between radar system clocks and a reference clock to compensate for clock drift by applying frequency compensation to transmitted or received radar signals, and manipulating the oscillation frequency of each radar system's clock to synchronize them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a common clock source is distributed to multiple radar systems, then frequency and phase synchronization is improved, but the clock signal becomes contaminated in harsh automotive environments
Solution Approach 1:
A reference radar system acts as an intermediary by providing timestamp information that mediates the time base relationship between transmitter and receiver radar systems. The timestamps serve as a reference that allows synchronization without direct clock signal distribution, avoiding contamination while maintaining measurement precision.
Solution Approach 2:
The patent replaces the physical clock signal distribution mechanism with a digital timestamp-based time base reference system. Instead of distributing electrical clock signals that are susceptible to contamination, the system uses digital timestamps embedded in data packets to establish time relationships, substituting a vulnerable mechanical/electrical system with a more robust digital information-based system.
2Object-affected harmful factors
If unique local clock sources are used for each radar system, then clock signal contamination is avoided, but frequency and phase differences arise between systems
Solution Approach 1:
The system implements feedback by having the reference radar system send timestamp information to other radar systems. These timestamps provide feedback about the time base relationship, allowing each system to adjust its measurements accordingly. The feedback mechanism enables synchronization without requiring identical local clock sources, maintaining measurement precision while allowing independent clock sources.
3Adaptability or versatility
If frequency and phase differences exist between radar systems, then relative time drift occurs, but this leads to dispersion of time of flight estimates and reduced sensor sensitivity
Solution Approach 1:
The patent addresses time drift by applying parameter changes to the signal processing. Specifically, it applies frequency compensation and time alignment transformations to the received signals based on the timestamp information. This changes the parameters of the signal processing to compensate for the clock frequency differences, thereby maintaining accurate time of flight estimates despite using independent clock sources.
Data Source
AI summary
A system includes first and second radar transceivers, a processor, and a non-transitory computer-readable medium storing machine instructions. The machine instructions cause the processor to determine a first frequency offset a1 and a first initial time offset τinitial;1 between a first clock signal for the first radar transceiver and a reference clock for the processor, and the processor determines a first clock drift for the first clock signal relative to the reference clock based on the frequency offset a1 and the time offset τinitial;1. The processor determines a second frequency offset a2 and a second initial time offset τinitial;2 between a second clock signal for the second radar transceiver and the reference clock, and a second clock drift for the second clock signal relative to the reference clock based on the frequency offset a2 and the time offset τinitial;2. The processor then compensates for the first and second clock drift.