Ambiguity solution

Discussion of FieldGenius related issues and questions.

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Joined: Thu Nov 18, 2004 6:25 am
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Ambiguity solution

Post by landmarksm » Fri Nov 19, 2004 7:08 am

Can anyone tell me what the parameters are set to when solving the ambiguities for a gps fixed solution?

Is there anyway to change these settings?


Eric W. Price, PLS
Landmark Surveying & Mapping, PLC
Clintwood, VA

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Jason Poitras
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Post by Jason Poitras » Wed Dec 15, 2004 2:22 pm

Just an update for our other visitors who visit the forum. Eric has a Topcon Topcon Hiper Lite+ and had a question about ambiguity fixing level and FieldGenius. We were communicating via email, but thought the following information might be helpful to other Topcon users.

The Topcon (Javad) GPS receivers do have a parameter known as "ambiguity fixing level". There are not too many other makes of GPS receivers which allow the user to modify this setting and this is beyond the scope of the majority of users.

The ambiguity fixing level parameter has three settings, low, medium and high which corresponds to 95%, 99.5% and 99.9% respectively. The default factory or reset setting is medium (99.5%) and FieldGenius sets this value to confirm the parameter. I would consider the medium setting to be a good generalized setting and if accuracy and reliability are an issue, the FieldGenius masks for PDOP, elevation and number of computed satellites would have a much more significant impact.

There is a method within FieldGenius for users to add or override existing FieldGenius commands which are sent to the receiver. These commands can be added to the GPS profile database and are sent to the GPS receiver after the FieldGenius commands are sent. This method of course requires some advanced knowledge for the user or we could set up some custom profiles.
Jason Poitras
General Manager

Terry Westendorf
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Joined: Mon Jul 12, 2004 6:00 am
Location: Chapel Hill, North Carolina

Post by Terry Westendorf » Sun Dec 19, 2004 7:20 am

Most high end dual frequency receivers have an ambiguity fiixing level and a
multipath mitigation level. These two settings should be available to the professional in the field. Thales Navigation dual frequency receivers have these settings and I wish Field Genius provided a way to access them. These
settings can make a difference in the quality of the shot under varied circumstances. Not all surveying work is in a open field without obstructions.
I realize that the command strings are receiver specific, however, a great solution would be to allow the user to type into a text window the specific command required and then allow them to send it to the receiver. That way Microsurvey bears no responsibilty and it also allows the professional the latitude they should after have.
Terry Westendorf, PLS
Chapel Hill, North Carolina


Post by Guest » Sun Dec 19, 2004 10:10 pm


You are asking the same people to let us type and send instructions to the GPS units that won't let us have control over how a total station traverse is balanced. They are also the same one's that "automatically" determine GPS control points closest to the "measured" points (regardless of the rotation of the control to the measured.... think about it) when localizing.

I wouldn't hold my breath......


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Joined: Thu Nov 18, 2004 6:25 am
Location: Clintwood, VA

Thanks for the help.

Post by landmarksm » Wed Dec 22, 2004 11:36 am


Thanks for the help. I will try this in the field after Christmas and post a reply here to let you and everyone else know what the results are.


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