Repeated Loss of Positioning

[no pinch and yllw jkt]

We recently started Geocaching using a Lowrance iFinderGO2. Last Saturday and Sunday, the 27th and 28th of October we had extreme difficulty holding a position. During the course of several minutes we lost and then reacquired our position repeatedly. This occurred in open sky about a half hour before sunset until dark. After dark we did not have this problem. Is this a problem with the unit, or is there a disturbance with the satellite signals due to solar wind? I don't believe the latter is possible, but this happened at the same time of day both days. We had not noticed it previously on the last three weekends we have been out.

[+Rattlebars]

Some may deny it, but I have problems at sunset with my Magellan. Dunno why, it may be the angle of the sun's radiation with the ozone layer. I lose fix most often at sunset than any other time, even heavy clouds.

[+EraSeek]

Check here for solar activity: http://www.swpc.noaa.gov/rt_plots/kp_3d.html

[no pinch and yllw jkt]

Check here for solar activity: http://www.swpc.noaa.gov/rt_plots/kp_3d.html

Thanks, that info is very helpful.

[no pinch and yllw jkt]

Some may deny it, but I have problems at sunset with my Magellan. Dunno why, it may be the angle of the sun's radiation with the ozone layer. I lose fix most often at sunset than any other time, even heavy clouds.

Thanx, good to hear others have same problem.

[+eagletrek]

And all the time I thought it was due to interference caused by the "Mothership" as it used the sunset to disguise it's passage to and froe through our atmosphere!!!!!

[no pinch and yllw jkt]

And all the time I thought it was due to interference caused by the "Mothership" as it used the sunset to disguise it's passage to and froe through our atmosphere!!!!!

[+bash177]

Solar activity doesn't have that much affect on your GPS. The main problem is the location of the sattelites in the sky. The picture below show the Geometrical Dilution of Precision (GDOP). In short, when the GDOP is a high number, the worst the GPS resulty will be. The lower the number, the better. This varies by day, location, sky visibility.

 

So if you are going to be in the woods searching, the morning and evening are not very good times. This graph is for the Raleigh area on 8/17/07. It really helps to plan when and where you will be searching.

 

Here is a link for the software http://www.trimble.com/planningsoftware.shtml

 

Hope this helps

 

[no pinch and yllw jkt]

Solar activity doesn't have that much affect on your GPS. The main problem is the location of the sattelites in the sky. The picture below show the Geometrical Dilution of Precision (GDOP). In short, when the GDOP is a high number, the worst the GPS resulty will be. The lower the number, the better. This varies by day, location, sky visibility.

 

So if you are going to be in the woods searching, the morning and evening are not very good times. This graph is for the Raleigh area on 8/17/07. It really helps to plan when and where you will be searching.

 

Here is a link for the software http://www.trimble.com/planningsoftware.shtml

 

Hope this helps

 

Edited November 23, 2007 by no pinch and yllw jkt

[no pinch and yllw jkt]

Solar activity doesn't have that much affect on your GPS. The main problem is the location of the sattelites in the sky. The picture below show the Geometrical Dilution of Precision (GDOP). In short, when the GDOP is a high number, the worst the GPS resulty will be. The lower the number, the better. This varies by day, location, sky visibility.

 

So if you are going to be in the woods searching, the morning and evening are not very good times. This graph is for the Raleigh area on 8/17/07. It really helps to plan when and where you will be searching.

 

Here is a link for the software http://www.trimble.com/planningsoftware.shtml

 

Hope this helps

 

That does explain it very well.

[+Rattlebars]

Thanks! That does make things "clearer"

[+EraSeek]

Granted, if you have a bad satellite configuration this can give you lousey accuracy, for sure, and you need to pay attention to your sat screen to see if they are spread out or lined-up (bad).

 

However solar activity certainly has a significant effect. What solar activity does is causes and active ionosphere, and this can greatly slow the GPS signal. A delay of signal of one nano-second (one-billionth of a second) will throw your position off by one foot!

 

On a normal day with good sat configuration and good sky view the ionospheric error is:

4.0 meters

 

This is why WAAS is so helpful, along with correcting a few other errors.