Leap seconds: Causing Bugs Even When They Don't Happen - Bert Hubert's writings
a day ago
- Leap seconds are controversial due to Earth's variable rotation, affecting timekeeping.
- Navigation satellites like GPS, Galileo, and BeiDou use monotonic clocks unaffected by leap seconds, broadcasting offset to UTC.
- Leap seconds are pre-announced months in advance, transmitted with truncated week number and day to save bandwidth.
- The last leap second was in December 2016; since then, no new leap seconds have occurred, leading to a 256-week gap.
- Bugs emerge when systems misinterpret leap second data, e.g., U-Blox receivers reporting a false imminent leap second, and a gpsd bug causing a 1024-week time jump.
- Negative leap seconds may be needed in the future due to Earth's rotation speeding up, posing potential software issues.
- GLONASS handles time differently by incorporating leap seconds directly, which can cause glitches during leap second events.