Trimble GeoXT - high horizontal error in field

[WorldFamousBrapples]

Hi all, I am working with a Trimble GeoXT 2008 model. It's set up in NAD 83, State plane feet (North Carolina). When in the field, and often connected to 6+ satellites, the top right of the screen indicates horizontal errors of 20+ feet! What can be going on here?

 

Can this be related to "real-time settings" where I can choose to always use (or wait for) integrated SBAS, or I can choose to use uncorrected GPS in the event that a corrected signal is not available? The bit of experimenting I've done indicates to me that the unit rarely acquires a SBAS signal and makes data collection very inefficient.

 

I can't find any settings that strike me as off, it all seems legit, except for this high horizontal field error. My post processed (i.e. differentially corrected) data indicates reasonable accuracy, always within <5 feet based on aerial images and the calculated horizontal error that Pathfinder Office gives me.

 

Any ideas? Thanks.

[+Walts Hunting]

I am guessing you are not using it for caching. With only 6 satellites 20' is actually pretty good. If you are under trees expect signal decrying.

[John E Cache]

Geocaches use WGS84 by default. Why are using NAD state plane?

[WorldFamousBrapples]

Geocaches use WGS84 by default. Why are using NAD state plane?

 

You guys are right, I'm not using this for geocaching. You guys seem to know GPS units, so I figured I'd ask here. Trimble doesn't have a good online forum (like ESRI products do, for example) for trouble shooting.

[seldom_sn]

Geocaches use WGS84 by default. Why are using NAD state plane?

 

You guys are right, I'm not using this for geocaching. You guys seem to know GPS units, so I figured I'd ask here. Trimble doesn't have a good online forum (like ESRI products do, for example) for trouble shooting.

I'm guessing you are using state plane coordinates to survey property corners or something similar, and that you've borrowed the Trimble from a surveyor. IIRC (fuzzy memory) some Trimbles require a ground station within maybe 50 miles of the survey site to achieve their centimeter accuracy. I'm not a surveyor, but I doubt you will find anyone on this site except a surveyor who geocaches for a hobby who can answer your question.

[wmclark43]

Geocaches use WGS84 by default. Why are using NAD state plane?

 

You guys are right, I'm not using this for geocaching. You guys seem to know GPS units, so I figured I'd ask here. Trimble doesn't have a good online forum (like ESRI products do, for example) for trouble shooting.

I'm guessing you are using state plane coordinates to survey property corners or something similar, and that you've borrowed the Trimble from a surveyor. IIRC (fuzzy memory) some Trimbles require a ground station within maybe 50 miles of the survey site to achieve their centimeter accuracy. I'm not a surveyor, but I doubt you will find anyone on this site except a surveyor who geocaches for a hobby who can answer your question.

Hi-

I am new to this geocaching, however I too use a Trimble Geoexplorer 6000. Also set up in the NAD83 cons format. I reset the unit to WGS 84 and all seems to work. My base map won't work because it is in the NAD coordinate system. My experience has been in developing a GIS map for our local water system showing meters, valves and such. All the answers from the previous posts seem corect. I had this large error in distance but was not entering (manually) the waypoint coordinates properly, had the west and east reversed. Any good ideas for info on conversions between different Nad - WGS systems?

Bill

[xyzee]

I use Corpscon to convert to/from State Plane, NAD 27, and NAD 83.

I haven't found a web site that will convert between NAD 83 and WGS 84.

On my old MobileMapper, the one that is like a refined Meridian Color, on the Position Page, will let me put 84 in the Primary and 83 in the Secondary position. It shows that 84 is about 2 ft N and 4 ft W of 83. This is for my Utah location, but it will be less of a difference as one goes E, and more as one goes W.

When set to DEG.DDDDD, and DEG/Min.MMM, 84 shows one number farther N and one number farther W than 83.

Seeing how close that NAD 83 and WGS 84 are to showing the same position numbers, is probably why Garmin, Maggie, and others, don't show the difference in their handhelds for us regular user folks.

[Grasscatcher]

FIRST......

Set your unit on whatever format,datum,etc that the source data is in (that you are wanting to INPUT)

 

Input the data............., then switch your unit back to whatever format that you (normally) use or just want to use.

 

Your unit does all the conversions internally, totally hassle free....