Multi-Device Clock Synchronization Using Indirect Timing Pulses
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Solution Overview
Problem
Existing clock synchronization methods fail to effectively synchronize clocks across multiple devices, particularly in systems like GPS and LiDAR, leading to data processing issues in applications such as autonomous vehicles due to clock drift and incompatibility with external synchronization signals.
Innovation Solution
A method and apparatus for clock synchronization across multiple devices, involving emitting timing pulses based on a first clock signal, generating reference data based on a second clock signal, and using processing devices to derive synchronization functions to align the first and second clock signals, even when direct synchronization is not possible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a master clock with PPS signal is used for synchronization, then clock synchronization accuracy is improved, but device compatibility is worsened because not all devices can receive and process PPS signals
Solution Approach 1:
The patent introduces a processing device as an intermediary that receives timing information from multiple sources (including PPS signals from master clocks and timing data from GPS/LiDAR devices) and derives synchronization functions to coordinate all clocks. This mediator approach allows devices that cannot directly receive PPS signals to still achieve synchronization through the processing device's coordination.
Solution Approach 2:
The processing device performs multiple functions: it receives timing information from various sources (master clocks, GPS devices, LiDAR systems), derives synchronization functions for each source, and coordinates all clocks in the system. This multi-functional approach enables universal synchronization across heterogeneous devices with different synchronization capabilities.
2Ease of operation
If GPS devices generate their own PPS signal for synchronization, then self-synchronization capability is improved, but system coordination is worsened because GPS clock signals may periodically change when new satellites are acquired
Solution Approach 1:
The processing device continuously receives timing information from GPS devices and other sources, compares the timing data, and derives synchronization functions that adapt to changes in clock signals. This feedback mechanism allows the system to detect and compensate for GPS clock signal changes when new satellites are acquired, maintaining stable coordination.
Solution Approach 2:
The synchronization system uses dynamic derivation of synchronization functions based on real-time timing information from multiple sources. The processing device continuously updates the synchronization functions to accommodate changes in GPS clock signals, making the system adaptable to dynamic conditions rather than rigidly fixed.
3Measurement precision
If LiDAR and other sensors use internal clock signals for timing, then processing accuracy is improved, but clock synchronization is worsened because these devices cannot synchronize to external clock signals
Solution Approach 1:
The processing device acts as an intermediary that receives timing information from LiDAR and other sensors using their internal clocks, and derives synchronization functions to coordinate these internal clocks with external master clocks. This allows LiDAR devices to maintain their internal processing accuracy while achieving synchronization through the processing device's coordination.
Solution Approach 2:
The patent segments the synchronization task into separate synchronization functions for each device type (GPS, LiDAR, master clock), deriving individual synchronization functions for each source and then coordinating them all through the processing device. This segmented approach allows each device to maintain its own timing characteristics while achieving overall system synchronization.
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
A method of performing clock synchronisation across multiple devices, the method including: in a first device: emitting timing pulses based on a first clock signal; and, outputting event data including events associated with first event times based on the first clock signal; in a second device: receiving the timing pulses; and, generating reference data including an indication of each timing pulse associated with a reference time based on a second clock signal; and, in one or more processing devices: receiving the event data; recording an approximate local event time for each event based on a time of local receipt determined using a local clock signal; using the local event times and first event times to derive a first function that relates the first clock signal and the local clock signal; using the first function and the reference data to derive a synchronisation function relating the first and second clock signals; and, using the synchronisation function to perform clock synchronisation of the first and second clock signals.