Post # 99 was created by mistake. Sorry.
I wanted to ask which files are in the folder RXN.
On my 3790 -> 3490 there is no RXN folder.
Last edited by mirbar; 13th February 2013 at 15:09.
1. It is clear that my Nuvi 3790T -> 3490 has better accuracy when I’m not in a move. It is about 4-6 meters.
2. City drive test – accuracy between 10 to 21 meters. Average accuracy 14-18 meters.
I have started with accuracy of 6-7 meters /car moves up to 20 kmph/, but as soon as I increased the speed, accuracy changed fast to worse. As you can imagine I tried to evaluate the reasons behind accuracy drop down. As far as I can recall now there are several reasons besides flashed Garmin firmware:
- No good visibility to satellites, caused by
a. buildings – I’m living in relatively small town with no very high buildings
b. trees – not much, at least it is winter time
c. bad weather – cloudy, but not bad
d. Roofs - non
- Strong magnetic fields – no
So more or less I have had normal city drive conditions.
I have noticed that my unit improved its accuracy, signal strength respectively, when its back side is faced to the sky. Signal strength improves with more than 15-25%. Most probably it is connected with antenna and for test purposes the unit was in most favorable position for good signal reception.
The first conclusion was – more speed – worse accuracy. I was not convinced and…
3. Disappointed by first results of city driving, left the town to nearby village just 15 km. away.
On the Stop sign in the end of the city I have checked accuracy 10 m. In the open areas without no trees and flat terrain the accuracy was between 10 and 12 meters. Speed varied between 90 and 130 kmph. So far, so good. I was wrong about the speed. When terrain changed – heights on the right side, accuracy dropped to 15-22 meters. Average accuracy for my outside city test – 14 – 17 meters. Average speed – 100 kmph.
These are the results.
Then stopped and go out of the car – again 4-6 meters accuracy. In stopped car – not less than 8-9 m.
My conclusion – despite improvement, the unit reception is not stable and its accuracy is too much voluntary. There were no change in any of the new files in rxn dir after the test. MSL_log.txt size is 0. No such a file like Dasilvarsa mentioned 36 rxn_config_.
@ Caty – when rxn dir showed up in your unit or it was there already when you bought it?
Last edited by isg; 13th February 2013 at 17:37.
It showed up later, I've a December 2010 3790 back up before conversion and a Feb 2011 34xx backup after conversion and no rxn folder in GPS directory is present in both of them. My actual files in rxn are dated Feb 2012.
Arc.bin, Bee.bin and mt.nvm are present in both backups.
I've do the same test today like Isg in post 103. In my 3790>3490 there was not RXN folder but only ARC.BIN BEE.BIN and MT.NVM files so i've use Lolypop000 RXN folder and then i've do the test for compare. With my only 3 files i have 6 - 10 meters accuracy and without my files and with RXN Lolypop000's folder i have 9 - 15 meters, so i (for now of course...) replace my old 3 files. Thanks to Lolypop000
The GPS folder holds the GPS Prediction Data for Fast Satellites Aquisition
I deleted the whole GPS Folder (Backed it up first of course)
Next I switched on Nuvi 3490
Nuvi took long to acquire satellites - 7 minutes To 3 meter Accuracy - Clear Sky
Connected Nuvi to Computer
GPS folder and all files were recreated by the Firmware.
Switched on Nuvi again.
Satellites were aquired immediately.
this proves our earlier suspicions that the GPS Folder does indeed hold the Predictive data.
Restored the "backed up" GPS Folder.
Switched on Nuvi.
Satellite aquision was immediate.
The difference between stupidity and genius is that genius has its limits.
I've delete GPS folder. Start nuvi, long time to see satellites and then (5 minutes about) 6 - 10 meters accuracy. In new gps folder there are 3 famous files. Then "Caty's solution" and restart. All ok, fast and 6 - 10 meters. Good for me. I replace my old GPS folder for see the differents but there is any differents. I think that my hardware use only 3 files