Is this a code only processing or is it carrier smoothed? What kind of occupation times are necessary for a 1 meter solution? What sigma level is the "1 meter" accuracy claim?

Sounds interesting. Although I sure do like our real-time reliance :)...

Is this a code only processing or is it carrier smoothed?
It's carrier-smoothed code and carrier phase processing - as with Reliance Processor but with a brand new differential correction engine.

What kind of occupation times are necessary for a 1 meter solution? What sigma level is the "1 meter" accuracy claim?

First of all, submeter accuracy is achieved with the post-processing option. Accuracy depends on the length of time that the receiver is on and logging data to a job - includes both the time spent logging GIS features and the time in between feature logging. The submeter accuracy is achievable with files as short as 15 minutes, assuming the standard conditions described in the data sheet (PDOP <4, >5 SVs tracked) and assuming you have good* reference station data. This is 2 sigma (95%). All tests were conducted by recording point features for 30 seconds. (The data for point features is automatically averaged after post-processing by MobileMapper Office 2.00.)

* By "good," I mean data from a MobileMapper receiver, any Thales/Ashtech survey-grade receiver (either L1 or dual frequency, though MM Office uses only L1 code/carrier) or RINEX data from any comparable GPS receiver.


Modified By Mike Margolis_ on 4/13/2004 at 7:01 AM

I am considering a Mobile Mapper for locating water and sediment depths before and after dredging while stationary in a boat. Are you indicating that shore based reference & control points should be "logged" for at least 15 minutes, and individual location points along lake transects logged for at least 30 seconds to get sub-meter post-processed? Two poles would be used to hold the boat stationary on low wind speed days. Thanks for any response. PB

The concept of the post processed data is that at least two GPS receivers are involved with one of them recording data on a point that is not moving. This would be the "base".

The MobileMapper being used for mapping the features that matter to you will have it's position computed relative to that base.

Point mapping implies that you are mapping a point. If you want to map things while you are moving you may want to log that as a line rather than a point.

Try it both ways and use what provides the most satisfactory results.

Modified By Phil athome on 5/1/2004 at 4:04 PM

Pardon the simple followup question, but...is the Mobile Mapper only capable of post-processed and repeatable sub-meter accuracy if working with a second receiver as a base, such as a Promark 2? If so, then by itself, it is only accurate to within 3 meters? The cost of the system suddenly jumps up. Perhaps having real-time sub-meter acc. would be more appropriate on water for selected points?

My personal preference has always been to operate my own base station for my mapping work. One of the reasons for that is my ability to control the recording interval and the power switch on that base station.

For many the use of CORS data will satisfy the expectations for post processed results. For others the unprocessed positions are sufficient.

We are talking about a tool with a variety of applications and much that needs to be mapped.