Bad Elf Flex App: Known Point Testing
Bad Elf Flex App: Known Point Testing
Introduction
Test the accuracy of the Bad Elf family of devices against a known point such as an NGS Monument.
Step-by-Step
- Start by Identifying Survey Monument Coordinates:
Look for a monument marked with a v1h1 control designation, denoted by a black square on the map, indicating the mark coordinates are of sufficient accuracy for reference.Use the Passive Mark Page to confirm the mark was recovered in the last recovery report and was not destroyed. This page also will give you all relevant attributes to be used in later steps.- Datum Conversion:
- Convert the coordinates of the chosen monument to the datum of your correction network if necessary, for example, if using Point One Navigation with the Bad Elf Flex Mini Extreme, or if testing in SBAS mode. These networks use the ITRF2014 and the ITRF2000 datums respectively with the current year epoch.
Most networks in the US are in NAD83(2011)(Epoch 2010).If a datum transformation is necessary, use a program like HTDP from the NGS. - Coordinate Format Conversion for Import into Bad Elf Flex App
- Convert the NGS coordinates from Degrees-Minutes-Seconds (DMS) to Decimal Degrees (DD) using a tool like NCAT.
- Import NGS Coordinates to Bad Elf Flex App:
- Preparation for Known Point Testing:
- Allow your Bad Elf GNSS receiver to warm up by attaching it to the survey pole underneath an open sky view until it has an SBAS fix with multiple constellations.
- Optional: establish an NTRIP connection to your RTK corrections network to ensure accurate positioning data.
- Setting Up the Bad Elf on the Monument:
- Position the Bad Elf over the identified survey monument.
- Ensure the Bad Elf and the survey pole are level and stable, ideally using a bipod, to avoid introducing errors to your measurements.
1 degree of tilt = 3.5cm of error - Open Deviation Plot in Bad Elf Flex App:
- Within the Bad Elf Flex App, open the deviation plot feature
- Press the “set” button at the bottom right to select the saved monument location from the "Saved Locations" list in the app.
- This allows for real-time monitoring of the Bad Elf’s calculated position and offset from the monument coordinates using Δ. We recommend taking screenshots of the results once the solution settles.
- Collect a point in the data collection -> standalone data collection menu once the Bad Elf is recording a stable position.
- This point can be exported from “Logs” and contains all relevant metadata for comparison.
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