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Using Total Station in Calibrated Site

Question asked by Sam Williams on Jan 23, 2019
Latest reply on Jan 29, 2019 by Sam Williams

Hello

 

I have conducted a site calibration on the site I work on, we are using a local base and streaming corrections over radio RTK to the rovers.

 

Our site sites on the UKs national grid (OSGB36 (15)) therefore a scale factor must be used to scale total station observations from ground to grid and vice versa. In the part of the country I am in I know the SF should be approx 0.9996xxxx.

 

When you examine the parameters in Trimble access for OSGB36 15 this is indeed the case, the SF displayed is "0.9996012717" this works perfectly with the total station and our set ups are very tight (>2mm) across the site (1.5km).

 

OSGB36 15 Parameters

The issue is when the site calibration is used to set the projection parameters Access calculates the wrong scale factor and applies a 1.000092460 to total station observations which is incorrect.

Site calibration parameters

 

I have tried re-calculating the calibration in TBC and exporting as a coordinate system but the problem persists, our GNSS measurements are perfect using this calibration however I would like to be able to use the total station in the same job.

 

Also where in access is the option to compute the SF every time the total station is set up as opposed to using a fixed number? this generally gives better results but I see no option for this.

 

Any ideas what is wrong here? I would really appreciate your help.

 

Cheers


Sam

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