When calibrating a site with Siteworks, I accidentally selected “no” at the end of the calibration when Siteworks asked if I wanted to save the base station as control point. (btw in what scenario wouldn’t you want to do that? ) I long for an auto-save button, but nonetheless I made the mistake. I went into task log and acquired the lat / long / elevation from that point and was wondering if there is a way to convert this into a Northing / Easting / Elevation in TBC and save the point?
Base Setup Date 7/30/2020
Base Setup Time 2:26:40 PM
Base Setup Base name 14TH
Base Setup Receiver type Trimble SPS985 SN: 5425F70461
Base Setup Corrections broadcasted via Radio in Receiver
Base Setup Radio type TNL900I
Base Setup Radio network 38
Base Setup Base ant. height(APC) 0.474 usft
Base Setup Base latitude 42°02’31.70656" N
Base Setup Base longitude 91°35’41.68687" W
Base Setup Base height 706.539 usft
Base Setup Elevation mask 10
Really appreciate your help.
Trev
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If you have a Project with the Site Calibration loaded into it and you have the LLH of the Base Station position, you can enter the LLH values as a Global Coordinate position into the Create Point Command (Coord Type Global) and it will compute the NEZ from the LLH values.
However what I am not sure on is whether that LLH is an accurate position or not, I think it should work because when you start the base on an unknown point it does a “Here” position (an instantaneous grab of a LLH value) which is then used in the Site Calibration which then computes the real position and determines the XYZ shift between the Here position and the real position. The Shift is in the Site Cal s when you enter the LLH (of the Base Station) it should compute the correct NEZ.
If the Base Position LLH that is stored is a corrected LLH and not the Here position then it also should back compute correctly.
You should field verify that the Base Point is correct though by taking a Rover up close to it and see if the coords are close - the Here position would normally be many feet off - so a rough check should verify.
Alan
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When evaluating the quality (accuracy) of the data you collect, you’ll need to know what you’re comparing it to. Although the GNSS receiver may tell you it is accurate to within 1 cm, that’s of little use if you can’t validate the results against something in the real world. Ideally, you’ll be able to collect some test data over known “benchmarks” or “control points” for which you know the accurate location in an “official” reference frame. These are often maintained by regional or national geodetic agencies.
The monuments that I have used in the past are labelled Geodetic control (Bench mark if your looking to verify your elevations. These are good to include into your Calibration. Static Post processing through RTX or Opus provides really accurate coordinates from my experience. I will also output LLH, Meters and Feet. Then I take those values which I Calibrate to .
geodetic control network is , often of triangles, which are measured precisely by techniques of terrestrial surveying or by satellite geodesy.
A geodetic control network consists of stable, identifiable points with published datum values derived from observations that tie the points together.
For instance:
- A nonzero hundreds digit tells us we’re using longitude, not latitude!
fourth decimal place is worth up to 11 m: it can identify a parcel of land. It is comparable to the typical accuracy of an uncorrected GPS unit with no interference.
sixth decimal place is worth up to 0.11 m: you can use this for laying out structures in detail, for designing landscapes, building roads. It should be more than good enough for tracking movements of glaciers and rivers. This can be achieved by taking painstaking measures with GPS, such as differentially corrected GPS.
seventh decimal place is worth up to 11 mm: this is good for much surveying and is near the limit of what GPS-based techniques can achieve.
ninth decimal place is worth up to 110 microns: we are getting into the range of microscopy. For almost any conceivable application with earth positions, this is overkill and will be more precise than the accuracy of any surveying device.
This is a lot of information but also depends on what the project consist of and determining what the GPS will be used for and the needed accuracy. Also it is very beneficial to have the base radio and rovers loaded with what is called the all codes. It allows you to see up to 30 Satellites depending were you are Surveying. IE: near structures that interfere with Line of sight or you distance from the Base Station.
I guess in a short note it all depends on what field procedure’s are used and the processing of the Data.
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