+braggsoldier Posted July 7, 2005 Share Posted July 7, 2005 I have had my GPSMAP 60C for a few months now, and was very impressed with its accuracy until I installed the newest firmware upgrade. Before I was always getting accuracy of 8-10' and alot of the time even 6'! Now I am lucky to get +- 14. Can someone help? Quote Link to comment
Neo_Geo Posted July 8, 2005 Share Posted July 8, 2005 Send me an email with your email address and I'll send you the 60C version 3.90 so you can downgrade. Quote Link to comment
+EraSeek Posted July 8, 2005 Share Posted July 8, 2005 The accuracy reading is only a programed guesstimate of how your unit is doing. It is not the true accuracy of your unit. I checked the Garmin site to see what they did with the download. I doubt if it had a ny effect on that program. If you had an accuracy of 6' before, that would probably reflect having a good WAAS fix and correction. 12' to 14' foot is more normal for a fix without WAAS and corrections. Are you sure that is not what you are seeing? Quote Link to comment
+braggsoldier Posted July 8, 2005 Author Share Posted July 8, 2005 I have the ver 3.90, I just didnt want to downgrade until I asked people on here. I seem to have good waas fix, but I can not get anything below a +- 14. Also, the unit will take forever to readjust when I stop and then start moving again even when I have a good position fix, is this normal? Quote Link to comment
+damel Posted July 8, 2005 Share Posted July 8, 2005 The accuracy reading is only a programed guesstimate of how your unit is doing. It is not the true accuracy of your unit. EraSeek is correct, the number you see like +-10ft are actually the Estimate of Position Error (EPE). This is more of a probability issue then an accuracy issue. The EPE says that you will be inside the sphere given that the confidence level (sigma) for the situation is high enough. It seems to be generally accepted that garmin uses a confidence level of 50% (50% CEP). If this is the case, then you have just as much chance of being inside of the 10ft circle as you do of being outside it. Thus the EPE is really not accurate at all, just a guess of the error of your unit. WAAS is probably a better guess for the difference. Maybe it was reset in your unit when you upgraded. In the setup menu make sure WAAS is turned on. I know my unit came in the box with WAAS turned off, which I thought was wierd. Maybe thats the default. See these for more info: http://factsfacts.com/epe.htm http://gpsinformation.net/main/errors.htm http://users.erols.com/dlwilson/gps.htm Quote Link to comment
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