GPS Clock Synchronization with Delay Compensation
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Solution Overview
Problem
Existing methods for synchronizing non-GPS equipment with GPS time face challenges due to variable delays and timing errors introduced during the processing and transmission of time of day (TOD) data from GPS receivers to external devices.
Innovation Solution
A method that processes multiple data sentences from a GPS device to determine the most accurate time information, accounts for delays in data processing and transmission, and corrects timing errors by adjusting time stamps and processing times to synchronize the external device's clock accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receiver transmits TOD data to external device, then external device can obtain time synchronization, but variable delays and timing errors are introduced during processing and transmission
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between data sentence byte counts and transmission times. Before actual time synchronization occurs, the system builds a lookup table mapping different data sentence lengths to their corresponding transmission durations. This allows the external device to compensate for transmission delays without real-time calculation, thereby reducing timing errors while maintaining accurate synchronization.
2Measurement precision
If multiple data sentences are processed to find most accurate time, then timing accuracy improves, but processing complexity increases
Solution Approach 1:
The patent employs this principle by using disposable time stamp values from multiple data sentences to determine the most accurate time. Instead of maintaining complex continuous tracking, the system processes individual time stamps from successive data sentences, compares them against the stored reference time, and uses the most accurate one found. This approach achieves high accuracy through multiple samples while keeping processing simple and stateless.
3Measurement precision
If time stamp adjustment is performed to compensate for delays, then synchronization accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating transmission times for different data sentence lengths and storing them in a lookup table. Before actual time synchronization is needed, the system establishes the relationship between byte count and transmission duration. During operation, this eliminates the need for complex real-time calculations, as the system simply retrieves the pre-computed transmission time corresponding to the actual data sentence length and applies the appropriate time stamp adjustment.
Data Source
AI summary
A method for synchronization of an external device's clock 324 with a GPS device 104 is provided. The method can comprise processing one or more data sentences received at the external device 106 from the GPS device to determine a data sentence containing the best available time information that is most accurate among the data sentences. Also, an amount of correction can be determined to compensate for one or more variable time delays introduced by one or more processes. The one or more processes can selected from a group consisting of a process performed by the GPS device t1b, a data sentence transmission from the GPS device to the external device t2b, and a data processing step performed by the external device t3b. A synchronization time using the amount of correction and the best available time information can be provided. The method can further comprise correcting a timing error introduced into time stamp values by the external device clock. This step can include removing an accumulate error by restarting the method after a pre-defined amount of time (e.g., one hour).