[the_biot]

The "travelling" part sounds like it could be an artifact of your GPS receiver interpolating between two vastly different location points, and interpreting that as moving between them -- at impossible speed/angle. So a single wildly wrong location could be enough to cause this.

Do GPS packets have a checksum?

[martyvis]

Id be fairly confident that they would. They also are encoded so that receivers that literally have no idea where they are can train on the received stream. Also don't forget that the receiver needs to hear signal from at least 3 or 4 satellites to be able to triangulate their position and altitude.

[the_biot]

The wikipedia page has some info, looks like various CRC and parity checks. Maybe the receiver was just ignoring them, and receiving faulty data.

I dunno, it seems to me like that GPS receiver had fairly bad software. If you get packets from a bunch of different satellites but one is way off, it seems like good sense to throw that one away.

[mysterydip]

It worked fine everywhere else I went for weeks, so while I'm sure it was a bug of some sort, I wouldn't say it was overall a bad receiver.