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I had a Volvo XC90 that “jumped” off the interstate and onto a parallel mountain road east of Knoxville. It did its best to track along those roads and somehow

I had a Volvo XC90 that “jumped” off the interstate and onto a parallel mountain road east of Knoxville. It did its best to track along those roads and somehow made its way into North Carolina. But even when I was back in Chicago, it was still stuck in NC trying to find a way off those mountain roads. Dozens of on/off cycles did nothing. I disconnected the battery overnight and that didn’t work. At the next service appointment, the dealer had to do a full firmware reset to wipe the memory and get it working again. It amazed me that Volvo programmed an SUV to disbelieve that it could ever actually leave a road.

kijin 10mo ago
My dad used to have a crappy aftermarket GPS in his car that did the same thing. It would get lost dozens of miles away, and then hundreds of miles away. The explanation I found online at the time was that a GPS receiver needs to download data about the exact orbits of all GPS satellites from time to time. Satellites slowly lose altitude and change their orbits. Up-to-date information is constantly broadcasted by every satellite, but it takes about 15 minutes for a device on the ground to download this dataset. Most GPS devices do this automatically whenever they get the chance. But if your GPS is somehow unable to stay online for 15 consecutive minutes (bad firmware, faulty memory, tunnels, underground parking lots, etc), it will be relying on increasingly outdated info and drift far off its actual location.
- pbmonster 10mo ago
  There's no way a modern smart phone or car relies on those ephemeris transmissions. They all just get it from the internet, which takes less than a second. That's one of the reasons why a smart phone has a reliable GPS fix basically instantly after being booted up, while old-school offline GPS units needed minutes to get a fix.
- malfist 10mo ago
  _deleted incorrect statement_
  - CamperBob2 10mo ago
    Well, that's certainly not the case. Each satellite transmits a low-precision almanac to the receiver that helps it lock onto the others, as well as a higher-resolution ephemeris that provides the necessary pseudorange accuracy for that particular SV. But it's true that neither of those factors accounts for miles of error. That has to come down to either poor sky coverage/signal strength, poor software, or (more likely) both.
    - malfist 10mo ago
      You are correct, there's several words of data at the end of the packet that is a low precision almanac
  - deleted 10mo ago
    [deleted]
- kccqzy 10mo ago
  That's only the case for non-internet connected GPS units. Throwback to the early 2000s when my family car had such a unit, which, after having been turned on, would require ~15 minutes of waiting before it became functional. Funnily, I remember the mapping app would refuse to use the device clock and only use the time from GPS satellites. So at least you would know you need to wait if it didn't know the current time.
doubled112 10mo ago
Last summer traveling down a rural road in southwestern Ontario, Apple maps told me to return to the route. We hadn't turned in 10 kilometers, but it was showing that we were 200 meters into a cornfield. I don't think I could have ended up there if I tried in the Golf we were in. Nice try. My kids thought it was the funniest thing, but it's a good technology lesson.
hnlmorg 10mo ago
The problem is that roads are continually being built and maps aren’t always as quick to be updated. There are also private paths that aren’t public roads but are still intended for vehicles.
- theamk 10mo ago
  That's no excuse for disbelieving GPS for extended periods of time. Google Maps gets it right: it tried to keep you on road, but only for a few tens of seconds. After that, if you are in the middle of uncharted territory, it'll show the marker there. (This is probably because Google Maps can be used for walking/biking too)
  - UebVar 10mo ago
    >(This is probably because Google Maps can be used for walking/biking too) Please don't do that. The map is simply not good enough and does not have enough context (road quality, terrain, trail difficulty) for anything but very causal activity. Even then I highly recommend to use a proper map, electronic or paper.
    - jonahrd 10mo ago
      yeah I'm not gonna open some paid trail map or buy a paper map so I can walk across my local city park and give my friends a pin to find me...
      - i80and 10mo ago
        I've found Organic Maps to be better than any paid app for hiking (and I've tried a bunch) for what it's worth
        teekert 10mo ago
        For anything other than driving Organic Maps (iOS) or OSMand (Android) are the very best.
        10mo ago
worewood 10mo ago
A badly programmed Kalman filter perhaps
- teekert 10mo ago
  Yeah, that is my guess, there must have been bug, issues where GPS suddenly teleports you. One way to remedy that is to give the roads virtual walls so what ever GPS weirdness comes in, the location service will at least put the car close to its "previous" location for some time.
pjdesno 10mo ago
In Boston it's a very frequent occurrence to be driving in the Central Artery Tunnel and have your map software think you're on the surface, or vice versa, or to be on a highway overpass and again have it think you're on a surface road that is inaccessible from your location. You get used to it. This seems like an entirely different level of craziness, though.
- kccqzy 10mo ago
  Yeah I remember back in the early 2000s before phones had turn-by-turn navigation, there were PDAs to do it and it was common for the software to just ask whether you were driving on the surface road or an elevated viaduct.
lostlogin 10mo ago
> It amazed me that Volvo programmed an SUV to disbelieve that it could ever actually leave a road. Only for footpaths in residential areas. I wonder what class of vehicles is least likely to go off roading?

kijin 10mo ago

My dad used to have a crappy aftermarket GPS in his car that did the same thing. It would get lost dozens of miles away, and then hundreds of miles away. The explanation I found online at the time was that a GPS receiver needs to download data about the exact orbits of all GPS satellites from time to time. Satellites slowly lose altitude and change their orbits. Up-to-date information is constantly broadcasted by every satellite, but it takes about 15 minutes for a device on the ground to download this dataset. Most GPS devices do this automatically whenever they get the chance. But if your GPS is somehow unable to stay online for 15 consecutive minutes (bad firmware, faulty memory, tunnels, underground parking lots, etc), it will be relying on increasingly outdated info and drift far off its actual location.

pbmonster 10mo ago
There's no way a modern smart phone or car relies on those ephemeris transmissions. They all just get it from the internet, which takes less than a second. That's one of the reasons why a smart phone has a reliable GPS fix basically instantly after being booted up, while old-school offline GPS units needed minutes to get a fix.
malfist 10mo ago
_deleted incorrect statement_
- CamperBob2 10mo ago
  Well, that's certainly not the case. Each satellite transmits a low-precision almanac to the receiver that helps it lock onto the others, as well as a higher-resolution ephemeris that provides the necessary pseudorange accuracy for that particular SV. But it's true that neither of those factors accounts for miles of error. That has to come down to either poor sky coverage/signal strength, poor software, or (more likely) both.
  - malfist 10mo ago
    You are correct, there's several words of data at the end of the packet that is a low precision almanac
- deleted 10mo ago
  [deleted]
kccqzy 10mo ago
That's only the case for non-internet connected GPS units. Throwback to the early 2000s when my family car had such a unit, which, after having been turned on, would require ~15 minutes of waiting before it became functional. Funnily, I remember the mapping app would refuse to use the device clock and only use the time from GPS satellites. So at least you would know you need to wait if it didn't know the current time.

doubled112 10mo ago

Last summer traveling down a rural road in southwestern Ontario, Apple maps told me to return to the route. We hadn't turned in 10 kilometers, but it was showing that we were 200 meters into a cornfield. I don't think I could have ended up there if I tried in the Golf we were in. Nice try. My kids thought it was the funniest thing, but it's a good technology lesson.

hnlmorg 10mo ago

The problem is that roads are continually being built and maps aren’t always as quick to be updated. There are also private paths that aren’t public roads but are still intended for vehicles.

theamk 10mo ago
That's no excuse for disbelieving GPS for extended periods of time. Google Maps gets it right: it tried to keep you on road, but only for a few tens of seconds. After that, if you are in the middle of uncharted territory, it'll show the marker there. (This is probably because Google Maps can be used for walking/biking too)
- UebVar 10mo ago
  >(This is probably because Google Maps can be used for walking/biking too) Please don't do that. The map is simply not good enough and does not have enough context (road quality, terrain, trail difficulty) for anything but very causal activity. Even then I highly recommend to use a proper map, electronic or paper.
  - jonahrd 10mo ago
    yeah I'm not gonna open some paid trail map or buy a paper map so I can walk across my local city park and give my friends a pin to find me...
    - i80and 10mo ago
      I've found Organic Maps to be better than any paid app for hiking (and I've tried a bunch) for what it's worth
      - teekert 10mo ago
        For anything other than driving Organic Maps (iOS) or OSMand (Android) are the very best.
      - 10mo ago

worewood 10mo ago

A badly programmed Kalman filter perhaps

teekert 10mo ago
Yeah, that is my guess, there must have been bug, issues where GPS suddenly teleports you. One way to remedy that is to give the roads virtual walls so what ever GPS weirdness comes in, the location service will at least put the car close to its "previous" location for some time.

pjdesno 10mo ago

In Boston it's a very frequent occurrence to be driving in the Central Artery Tunnel and have your map software think you're on the surface, or vice versa, or to be on a highway overpass and again have it think you're on a surface road that is inaccessible from your location. You get used to it. This seems like an entirely different level of craziness, though.

kccqzy 10mo ago
Yeah I remember back in the early 2000s before phones had turn-by-turn navigation, there were PDAs to do it and it was common for the software to just ask whether you were driving on the surface road or an elevated viaduct.

lostlogin 10mo ago

> It amazed me that Volvo programmed an SUV to disbelieve that it could ever actually leave a road. Only for footpaths in residential areas. I wonder what class of vehicles is least likely to go off roading?