How far is your GPS drifting?

[ErikSkulason]

Hi.

After you start your GPS and the navigation software, and if you don't drive/move AT ALL for about 10-15 minutes, how far are the green dots moving around?
(Using the Measure Tool, find out the distance btw. 2 extremes points).

I am using a non-Delorme BT GPS and noticed that sometimes I could measure up to 600-700 FT.

Just wondering if other types of GPS are drifting the same (with a 3D fix - green dot).

[Emrol Ed]

Here is one example.

[Sanaghan]

I am using a non-Delorme BT GPS and noticed that sometimes I could measure up to 600-700 FT.

I get the same with my Garmin; odd points drag in.
I don't get that with the SiRF or new PN-20 chipsets.

This is indoors.
I do not have that issue outside. Drift is much smaller when sitting still outside.

Moving is even better as the filter kicks in.

[xapie128]

After you start your GPS and the navigation software, and if you don't drive/move AT ALL for about 10-15 minutes, how far are the green dots moving around?

The graphic below was made under the following conditions:

• GPS Receiver: BU-353, SiRF III chipset
  
• First floor of a 3 story brick building, receiver hanging in a south facing window
  
• A similar 3 story brick building sits about 40 feet to the south
  
• Plot contains 16,000 points, recorded during a 4-hour 30-minute period
  
• WAAS (3D-DGPS) lock during the entire period

(Pls. excuse my English (foreigner, resident in IL, US))

Hey, your post reads better, and with less errors than at least 30% of the posts I read here

[ErikSkulason]

... or where is the "well known" precision (of about 10meters/30 feet) mentioned everywhere in the specs of almost any GPS ?

[Emrol Ed]

Is this significant drifting result of the distress signal?

I don't know what you mean by "the distress signal".

In the examples that Xapie128 and I posted, we were showing that certain receivers showed much less drift than you reported, while in less-than-optimal receiving conditions.

[ErikSkulason]

Is this significant drifting result of the distress signal?

I don't know what you mean by "the distress signal"....

Chances are that I misundertood AND mis-used the word "distress"

I was kind of wondering if the "Selective Availability" is still on. but there is a lot of math and complex factors involved in all this GPS guidance and measurements. Sorry for my mistake.

This quote is from wikipedia:
"Initially, the highest quality signal was reserved for military use, and the signal available for civilian use intentionally degraded ("Selective Availability", SA). This changed in 2000, with U.S. President Bill Clinton ordering Selective Availability (SA) turned off at midnight May 1 2000, improving the precision of civilian GPS from about 1000 feet to about 65 feet".

[xapie128]

I was kind of wondering if the "Selective Availability" is still on.

No, it is OFF and will remain OFF.
See: http://forum.delorme.com/viewtopic.php?f=42&t=12023&p=57316