Superb sat nav positional accuracy issues

[Gyp]

My Sportline has what I guess is called the Columbus (I used to under stand which radio was which) and has an interesting "feature".

 

Whilst the navigation system works, the location is sometimes a fair way away from where it should be. By which I mean if I'm driving along, the system might place me somewhere adjacent to where I actually am. It doesn't happen constantly, but it does happen a lot.

 

In the example here, the car things that I'm off road about 50m away from my actual position (shown by the black arrow)

 

https://i.imgur.com/GSB40fo.jpg

 

Whilst I can generally work out where I actually am this can be quite frustrating when I'm perhaps driving along a main road quite happily and the system is going mad trying to navigate me out of the adjacent housing estate.

 

Using Android Auto the effect is the same because when the phone is connected to the car, it uses the car GPS position as opposed to the phone GPS. When I use the phone disconnected it gets the position correctly, and I can also navigate correctly with my 20 year old Garmin sat nav sat on the the dash.

 

When I first took it in to Skoda, they deep a "deep reset" of the sat nav system which, other than giving me a new Sportline splash screen on start up made no difference.

 

Since then they have replaced the roof antenna and it seems a little better but the problem hasn't gone away - the pic above is with the new antenna.

 

Anyone else suffering the same? Anyone else solved the problem?

Edited 3 July, 2021 by Gyp
Hmmm... how have I forgotten how to include pictures..?

[Gyp]

Please bear with - I post images so infrequently I always seem to struggle...

[john999boy]

Android Auto should always use the phone's GPS. 

[Gyp]

12 minutes ago, john999boy said:

Android Auto should always use the phone's GPS. 

 

It uses the navigation app on the phone, but the positional information from the car. 

 

It took me a long time to discover this.

 

For months I'd been convinced that the problem I was having was a generic GPS issue as the position was off whether I was using the car navigation or the android auto navigation, but later discovered that when connected, android auto uses the car GPS signal and there's no way I've found of getting to to use its own

[john999boy]

I can only say that I've not seen this mentioned elsewhere. 

If you run AA purely on the phone then it definitely can't use the car's GPS - or are we talking about some sort of AA wireless? In saying that, AA could still be used when nowhere near a car so........

[MartiniB]

2 hours ago, john999boy said:

Android Auto should always use the phone's GPS.

wrong, reception of GPS signal is awful in phone box area
phone box provides only GSM signal, but not LTE and GPS :(

-> https://www.briskoda.net/forums/topic/395894-what-exact-option-kills-gps-signal-reception-under-windscreen/

 

 

@Gyp

have had that two times, position were several kms away

reboot of Columbus din't helped, have no details what 'deep reset' were done by dealer to solve

 

[langers2k]

I assumed Android Auto always used the phone GPS. Just had a quick google and it seems that AA can request the car GPS data (where fitted).

 

Google maps supported it first and Waze users have requested it as an improvement. It was a while back so I'm not sure if they've actually added support yet...

 

It can only be the GPS antenna, wire or the headunit/software that's at fault. Seems like they've ruled out the GPS antenna so that leaves the wire or headunit/software. At this point, if I were you I would:

- Make sure the software on the headunit is fully updated

- Buy a cheap fakra GPS antenna from eBay and try that (eg: https://www.ebay.co.uk/itm/224465036559)

 

Assuming you're fully updated, if the GPS antenna fixes it, the wire in the car is causing your issues. If it doesn't, it's more likely to be a hardware issue in the headunit

 

Oh, actually, I just remembered a TPI regarding damaged GSM/GPS fakra connectors - so check those are in good condition too. In the example below, the circled tangs need pushing inwards to repair the connector:

[Gyp]

15 minutes ago, langers2k said:

I assumed Android Auto always used the phone GPS. Just had a quick google and it seems that AA can request the car GPS data (where fitted).

 

Google maps supported it first and Waze users have requested it as an improvement. It was a while back so I'm not sure if they've actually added support yet...

 

It can only be the GPS antenna, wire or the headunit/software that's at fault. Seems like they've ruled out the GPS antenna so that leaves the wire or headunit/software. At this point, if I were you I would:

- Make sure the software on the headunit is fully updated

- Buy a cheap fakra GPS antenna from eBay and try that (eg: https://www.ebay.co.uk/itm/224465036559)

 

Assuming you're fully updated, if the GPS antenna fixes it, the wire in the car is causing your issues. If it doesn't, it's more likely to be a hardware issue in the headunit

 

Oh, actually, I just remembered a TPI regarding damaged GSM/GPS fakra connectors - so check those are in good condition too. In the example below, the circled tangs need pushing inwards to repair the connector:

 

 

Cheers - I bought a couple of external antennas recently as my old Garmin won't work sat on the dash without them (heated windshield) but unfortunately I don't think they have Fakra connectors. Actually I'm sure they don't.

 

Waze has now been updated to use the car antenna, so I can't use that to get round the problem. 

 

Whilst I'm tempted to discover how to get into the back of the head unit and try an external antenna, while this is still being treated as a warranty issue, I'm avoiding the temptation to fiddle. The car is out of warranty, but the problem was reported whilst it was in warranty but I don't want to give Skoda a get out.

 

I'm not sure if the antenna on the car has all the wiring through to the head unit of if it decouples at the antenna base - i.e. if replacing the antenna does replace the cabling through the headlining or if that's likely still the original.

[Gyp]

2 hours ago, john999boy said:

I can only say that I've not seen this mentioned elsewhere. 

If you run AA purely on the phone then it definitely can't use the car's GPS - or are we talking about some sort of AA wireless? In saying that, AA could still be used when nowhere near a car so........

Yes, if you use AA purely on the phone then it doesn't use the car's GPS.

 

However, as soon as you plug the phone into the car's USB socket such that you can use AA on the head unit, it swaps to using the car's GPS.

 

I could fit a dash mount for the phone but that somewhat defeats the purpose of all the expensive tech in the car.

[KenONeill]

Standard GPS is only accurate to about 15m (source Wikipedia), and I do know of places where that would put you on a different road, or on the opposed carriageway of the road.

 

Does AA use DGPS, since that has centimetric accuracy?

[Gyp]

10 minutes ago, KenONeill said:

Standard GPS is only accurate to about 15m (source Wikipedia), and I do know of places where that would put you on a different road, or on the opposed carriageway of the road.

 

Does AA use DGPS, since that has centimetric accuracy?

 

I don't think it does use DGPS though I could be wrong, after all I didn't realise that AA used the car's GPS system for years...

 

15m would likely be close enough, but in the example I gave, the position was about 50m out which is enough to get it to put the position way off to the side (or ahead, or behind)

 

Both the car and the Garmin seem to be identifying the same number of satellites (and it's still 8+ when the location is wrong), however the Garmin handily says what the accuracy is. Not sure if there's a hidden menu on the head unit that provides that.

[Berisford]

It's the same in Karoq, using the built-in Skoda sat-nav it's easy to miss a turning in crowded places because of the 50m lag - the Waze via CarPlay is bang on...........

[xman]

I may be wrong but afaik, AA and Apple Carplay merely use the Infotainment screen and sound system as external monitors, keyboard and speaker. I don't think they use any other onboard system such as the cars gps system or antenna or car's steering angle/compass/speed etc.

 

The (theoretical) advantage the car's native navigation has, is access to a proper external antenna, and the car's speedo compass/direction, steering angle etc which should help the gps software snap to more or less the correct position on a road.

 

Since Selective Availability was abandoned back in the last decade, GPS accuracy is usually pretty good at an average of 5m in good conditions.

 

https://www.gps.gov/systems/gps/performance/accuracy/

 

Newer navigation systems and phones don't only rely on GPS, they can also use GLONASS, BEIDOU, and GALILEO which is supposed to give 1m accuracy

 

[Gyp]

16 minutes ago, Berisford said:

It's the same in Karoq, using the built-in Skoda sat-nav it's easy to miss a turning in crowded places because of the 50m lag - the Waze via CarPlay is bang on...........

 

I've no idea if iOS devices with carplay work the same as Android does with AA.

 

I often have this issue in wide open spaces - on the M5 for example when it's determined that I'm in a farm. so it's definitely not signal reflection issues

[Rustynuts]

9 hours ago, Gyp said:

 

Cheers - I bought a couple of external antennas recently as my old Garmin won't work sat on the dash without them (heated windshield) but unfortunately I don't think they have Fakra connectors. Actually I'm sure they don't.

 

 

If your new GPS antennas have SMB connectors then these are effectively just the same as the Fakra connectors. The Fakra blocks are simply plastic shrouds colour coded and fitment tabbed to ensure correct connection. You can push a SMB connector into the Fakra socket on the rear of the Columbus, it just won't lock in.

[Gyp]

10 hours ago, Rustynuts said:

If your new GPS antennas have SMB connectors then these are effectively just the same as the Fakra connectors. The Fakra blocks are simply plastic shrouds colour coded and fitment tabbed to ensure correct connection. You can push a SMB connector into the Fakra socket on the rear of the Columbus, it just won't lock in.

 

That's worth knowing.

[NJRJ]

With a hiking GPS receiver an error of 15-50m is usually down to the GPS Datum being different from the map datum, the most common datum is WGS84 no idea what datum Skoda use for maps and from the GPS.

 

I've see something similar to the imgur image when on a new road that the map doesn't know about - most recently A1 between Leeming and Barton, though I don't think that is the case here.

 

[KenONeill]

1 hour ago, NJRJ said:

GPS Datum being different from the map datum, the most common datum is WGS84 no idea what datum Skoda use for maps and from the GPS.

Sounds plausible; these are definitely differences N-S between the WGS84 and Airy's Spheroids, and between the OSGB 36 and OSGB70 grids (BTW OS maps still use OGB36).

[Gyp]

This is old established roads and not the same each time. The M5 has been there for a while.

Edited 4 July, 2021 by Gyp

[KenONeill]

18 minutes ago, Gyp said:

This is old established roads and not the same each time. The M5 has been there for a while.

And that just means the  nav app is consistently wrong if it uses, say, ITRF and the GPS it takes the positioning pulses from uses WGS84. This is part of what I do as a day job.

[Gyp]

1 hour ago, KenONeill said:

And that just means the  nav app is consistently wrong if it uses, say, ITRF and the GPS it takes the positioning pulses from uses WGS84. This is part of what I do as a day job.

Ken, if that were the problem, wouldn't that mean that the "feature" would be common across all VAG cars with the same bead unit?

 

 

[Gyp]

Oh, I might be doing the photos right...

 

I pulled into the side of the road for the photo. I'm actually on the B road, just before (lower) than it's shown on the map

 

Here I'm parked on the A3102, just past Marlow Way

 

On the return journey, still on the A3102, pretty much on the dot under Wootton

 

Note that heading both directions, it's placed me to the North(ish) of the road that I'm on

[Gyp]

For the last one, here's where the trusty Garmin put me

 

 

[KenONeill]

1 hour ago, Gyp said:

Note that heading both directions, it's placed me to the North(ish) of the road that I'm on

Which is entirely consistent with a systematic conversion error. Since you did "move" the car between shots, there could also be a rounding error in here someplace, depending on which way it's doing geodysy. I would need access to the code, and a geographer who's also a coder and a consenting mathematician to get much further!

[Gyp]

4 hours ago, KenONeill said:

Which is entirely consistent with a systematic conversion error. Since you did "move" the car between shots, there could also be a rounding error in here someplace, depending on which way it's doing geodysy. I would need access to the code, and a geographer who's also a coder and a consenting mathematician to get much further!

 

Whereas who I've got a Skoda workshop manager. Would he do?