Just started a thread on the Superb III section which might have sat better here.

 

The nav often determines my position to be up to about 50m away from where I actually am.

 

Not all the time, but often enough to be annoying.

 

Skoda have done a deep reset of the system (whatever that means) and then replaced the antenna when the first fix didn't work and it's still not right.

 

Any thoughts? Am I alone?

GPS position accuracy depends on how many satellites it is receiving and able to decode - and how fast you are driving as it's only updated maybe once a second.

 

Based on having car sat navs for 15+ years I would say 50m sounds not unusual when reception conditions are poor (thick cloud, heavy rain, etc.) or you are driving at say 60mph or more.

On 03/07/2021 at 10:41, PetrolDave said:

GPS position accuracy depends on how many satellites it is receiving and able to decode - and how fast you are driving as it's only updated maybe once a second.

 

Based on having car sat navs for 15+ years I would say 50m sounds not unusual when reception conditions are poor (thick cloud, heavy rain, etc.) or you are driving at say 60mph or more.

Before coarse aquisition was turned off by the Americans in the late 90s, civilian GPS used to randomly place plots anywhere inside a 100 metre circle for around 90-95% of the time. Much more accurate since 2000 but you will still get a certain amount of 'randomising' in a civilian GPS receiver - you can check this using tracking mode on a stationary portable receiver over a period - the plot track will show movement of at least 25 to 50 metres over an hour.

I suspect car receivers use an algorithm to place the vehicle plot onto the nearest likely road on the map using recent history.    

I have a GPS runners watch, I realise that it takes plots periodically and effectively "fills in the gaps" based on my known speed and stride rate from the accelerometer, when I look at the map on the app and zoom right in I am amaazed that I can even see when I run one side of a footpath or road in one direction and the other on the return, I can see where I stop for a pee but at halts like that it cant really guess and it shows me meandering around where I did not go.

 

I also used it a few times to monitor my changeovers of the appartments, the cleaning, laundry etc as I can easily rack up 10k paces on a day like that across the 3 floors without ever leaving the building.

 

Clearly it loses it loses sattelite contact a lot while I am inside and the map when enlarged is a massive scribble showing me meandering in a radius of 25m all around my property whereas I was always within it.