GNSS Receiver Leap Second Offset Calculation
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Solution Overview
Problem
Current GNSS receivers face delays in combining Glonass satellite measurements with GPS or Beidou due to unknown leap second offsets during factory resets or cold starts, leading to prolonged Time To First Fix (TTFF).
Innovation Solution
A GNSS receiver is designed to calculate the leap second offset by measuring the time difference between GPS/Beidou data frames and Glonass data frames, allowing for rapid integration of Glonass with other GNSS systems by determining the UTC system time offset using a microcontroller and memory to store and process satellite time information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver waits for GPS to transmit the offset between GPS time and UTC, then the leap second offset can be determined accurately, but the Time To First Fix (TTFF) is significantly prolonged
Solution Approach 1:
The receiver performs preliminary measurements of the time difference between GPS data frames and Glonass data frames as soon as signals from both systems are acquired. By calculating the leap second offset from these preliminary measurements before GPS transmits the official offset information, the receiver determines the offset in advance, reducing TTFF while maintaining accuracy through subsequent verification and adjustment when the official offset becomes available.
2Loss of time
If Glonass measurements are combined with other GNSS systems measurements immediately, then TTFF is reduced, but the combination may be inaccurate without known leap second offset
Solution Approach 1:
The receiver implements a feedback mechanism where the initially calculated leap second offset from time difference measurements is used to enable early Glonass combination, and then this offset is continuously verified and adjusted when GPS transmits the official offset information. This feedback loop ensures that the navigation solution maintains high reliability by correcting any initial offset estimation errors while still achieving rapid TTFF.
Data Source
AI summary
A method for use with a Global Navigation Satellite System (GNSS) receiver is provided. The method includes obtaining a first system time from a satellite of a first satellite navigation system, obtaining a second system time from a satellite of a second satellite navigation system, calculating a difference between the first system time and the second system time to obtain a number of leap seconds between Coordinated Universal Time (UTC) and the second satellite system.