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I don't think every GPS receiver necessarily has to have this problem, even with the old signal. It's not crazy to keep a week count in persistent memory and us
by echoangle 8d ago
I don't think every GPS receiver necessarily has to have this problem, even with the old signal. It's not crazy to keep a week count in persistent memory and use that as a lower bound on startup so you only get a wrong time if the receiver isn't online for 1024 weeks.
- myself248 8d agoExactly. The sane ones just ask you what year it is at startup, and use that to determine the initial epoch. Then they handle rollover automatically since then. It's been widely opined that 1024 weeks (~20 years) is the worst possible interval. Either rollovers should've happened VERY frequently (say, 128 weeks) so receivers would be FORCED to deal with it, or extremely infrequently (16384 weeks?), so it's simply never an issue. The unhappy medium is long enough that developers feel justified in saying "naaaah, our receiver won't still be in use then, we can ignore that!", but in practice it's very likely to happen.