Out-of-phase clock signals for LIDAR time measurement error cancellation
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Solution Overview
Problem
Existing measurement systems in LIDAR systems face inaccuracies in determining the time of event signals due to offset errors caused by the phasing of event signals with respect to reference clock pulses.
Innovation Solution
A measurement system comprising two time determining devices that receive out-of-phase clock signals, allowing for the cancellation of offset errors through averaging, thereby improving the accuracy of time determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reference clock signal is used for time determination, then the device complexity is reduced, but the measurement precision deteriorates due to offset errors
Solution Approach 1:
The single reference clock signal is segmented into multiple clock signals (first clock signal and second clock signal) with different phases. Each time determining device uses a different phase segment of the clock signal, allowing offset errors to be distributed and subsequently cancelled through averaging, thereby improving measurement precision while maintaining manageable device complexity
Solution Approach 2:
The phase parameter of the clock signal is changed to create multiple clock signals with different phase relationships (e.g., 0度和180度out of phase). This parameter change enables the system to achieve higher measurement precision by exploiting phase differences to cancel offset errors without significantly increasing device complexity
2Measurement precision
If multiple time determining devices with different clock phases are used, then the measurement precision is improved through error cancellation, but the device complexity increases
Solution Approach 1:
Multiple time determining devices are merged into a single measurement system that processes signals from both devices. The results from multiple devices are combined through averaging, achieving error cancellation and improved precision while managing device complexity through integrated processing
3Measurement precision
If the clock signal frequency is increased to improve time resolution, then the measurement precision is improved, but the device complexity and susceptibility to offset errors increase
Solution Approach 1:
The system uses periodic clock signals with different phases to sample the event signal. By utilizing the periodic nature of the clock signals and the out-of-phase relationship, the system achieves high time resolution through multiple sampling points per clock period, improving measurement precision while managing clock system complexity
Data Source
AI summary
Disclosed is a measurement system comprising a first time determining device, a second time determining device and a clock signal system. The first time determining device is arranged to receive a first clock signal from the clock signal system and use it as a reference to determine a first time for an event signal that the first time determining device is arranged to receive. The second time determining device is arranged to receive a second clock signal from the clock signal system and use it as a reference to determine a second time for the event signal that the second time determining device is also arranged to receive. The first clock signal and the second clock signal are out of phase with each other.