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RNS-E Positioning/Updating

3671 Views 18 Replies 10 Participants Last post by  BBC
Hopefully someone in this forum has run into this issue before, I can't find it in any search.

Periodically, upon startup, my RNS-E is VERY, VERY, VERY sluggish in updating my position on the road. It appears as though it is only updating the position every 2 minutes or so, then the map changes to the recent position and stays there for another couple of minutes, and then updates hte position again. The other odd thing is that the orientation of the car on the RNS-E doesn't change to the dorection of travel, the position arrow stays pointed in the same direction no matter what way I'm travelling.

Eventually, sometimes after 20-30 minutes, it starts to work properly. And it is not consistent. Occasionally, it works properly right away. I have read about some thoughts about cold weather balkiness, and I do live in Minnesota, but the car sits in a 50 degree garage.

Any thoughts from this august group would be greatly appreciated. :lol: :lol:
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Mine has never performed this way and I have had very cold mornings. Perhaps you GPS antenna is fouling up. Try leaving it on the info screen next time and see how many sats you are receiving during this sluggish time.
mine does that too. i'm in chicago and i park in an undeground garage.

but i have bad reception around where i live (2-4 satelites).. it takes anywhere between 2-8 minutes to update its location according to the satelite.. then after that it updates more often and runs fine
Sounds like either your GPS antenna connection is bad, or the GPS antenna is not mounted in a place that gives a good signal.
I have mine mounted behind the instrument cluster and I get usually at least 5-7 satelites when I'm on the road or at a friends place. Now, when I park at home on the 5th floor of a concreted parking garage, I first drive up 5 floors in 360 degree circles and later the other way back down which makes 10 360 degree circles without any GPS signal.

When I leave the garage the RNS-E still knows where I am but has no idea which direction I go. Even after a minute when I'm back getting 3-4 satelites, it still thinks I'm heading east while I'm driving west. This is while driving between high risers in downtown Chicago but it usually takes about 5 minutes for it to clear up its mind and point into the right direction.

I don't know if the roof GPS antenna would solve this but I got used to it.
mine does exactly what dirk describes.. especially in the chicago ROW self parking structure.. when i drive out for 5 minutes it thinks i'm driving on top of lake michigan sometimes :lol: :lol:
adrianma said:
mine does exactly what dirk describes.. especially in the chicago ROW selt parking structure.. when i drive out for 5 minutes it thinks i'm driving on top of lake michigan sometimes :lol: :lol:
That's pretty normal behaviour for ANY GPS system after you come out of a parking garage.

The GPS signals really are VERY weak, and because the satellites have moved between the time you go into the parking structure and come out the GPS receiver is intially looking for the wrong satellites, so it takes a while for it to realise this and search for whatever satellites are now visible.

GPS is good, but it can't break the laws of physics!!!
The GPS satellites ephemerides data (orbit data), is encodeded on top of the data stream sent by the GPS satellites. The GPS satellites send out 24 hours of data at a time, so as long as you're car hasn't been parked for more than 24 the RNS-E should have a pretty good idea where the satellites will be.

It sounds like the traveling the wrong way problems are due to multi-path issues near tall buildings (this is where instead of receiving the signal directly, you receive it after it has bounced off something like a building). I bet the sharkfin antenna would do much better in filtering that out (because there is a large ground plane surrounding it).

With all that, I frequently park in a parking garage several floors up. I've never seen any odd behaviour out of my RNS-E upon leaving.
Thanks for all the replies.

I have the GPS antenna sitting on the dashboard, up next to the windshield. Typically, I have 4 satellites viewable at any given time, rarely more than that.

Perhaps I can try to run the antenna to the sharkfin, but that is currently being used for the SAT radio and OnStar, I don't know if it will support a third device. Maybe I'll get rid of OnStar, never use it anyway.
Navigation data is a mix of speed signal+ maps data + GPS signal.
One of these factors is failing. 4 satellites is not much but from what I read, I would recommend to check speed signal.

Mostlikely your nav is geting ping position from sat but don;t have enough of data to calculate real time.
Do you think an incorrect tire size programmed via VAG-COM would make a difference? I don't have the ability to change those settings, but I'm pretty sure they are not right at this point.
i think thats whats making my gps move slower than i actually am.. but i haven't have a chance to find someone free with a vag-com to help me yet..

i'm about 20% slower, so i drive 5 blocks and nav shows i've driver 4, but every minute or two when it updates from the satelites it will be correct again
The best way to check is to maximize your zoom, drive and observe nav screen. If your current position is incorrect or arrow sits in one place for too long then you have a problem with one of te signals (either antenna or speed)
I took the advice of checking the number of satellites the RNS-E was seeing, and initially it was only two! That would explain the slow updating. Once it saw 5-6 satellites, the unit worked fine. I'm not sure why it is taking so long to find the other satellites (sometimes 15-20 min), but that seems to be my issue.

I may try to attach to the sharkfin as an alternative.

Thanks again for all the help! :D
Roof mounted GPS Arial

I recently changed my GPS arial from inside the car to the Audi shark fin outside the car mainly did this as i wanted an arial for my phone and the shark fin is a 2 in 1 arial (GPS and phone) since i changed it, i receive 8 satelites consistantly, at worst 7 and my posistion is bang on and updated alot quicker than with my old GPS arial
How do you go about using the shark fin for the GPS antenna? I have a shark fin on my A4 but i use a different GPS antenna...
The RNS-E is programmed to adapt to tire size after a while. Usually it take just a few miles, but it will adapt. If you've had this unit in for any period of time your tire size is adapted by the differnce in vehicle road speed (calculated by tire revolutions x tire size), and actual road speed (satalite calculated speed). The computer corrects the the vehicle road speed until it agrees with the actual road speed. It does this by adapting the tire size automatically. But it is always good to use the tire chart for the initial starting point. Tires will change circumference as they wear, so ithe RNS-E may still tweek the value a bit.
Bottom line is, I don't believe all these guys are having vehicle speed problems. Put in the factory antenna and be done with all these reception, and map jumping issues.
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