Ditch Assists computes true ground elevation at all times by taking account of measurements entered by the user. Failure to enter measurements (or re-enter them after an app update) may cause the system to operate unexpectedly.
It's a good idea to keep a note of these measurements in case you need to re-enter them in the future.
In Settings, we ask for two measurements. These should be entered in either inches or centimetres, depending on the distance setting you have selected:
- Blade to Ground Height (in transport mode): This is the height of the cutting edge above the ground when the implement is raised all the way up. We need this measurement to compute true ground elevation when you survey using the implement. Manually raise the implement to its highest position (or the position it will always be in when you survey) and measure the distance from the cutting edge to the ground. Enter this in Settings in the App.
- GPS to Blade Height/Calibration Factor: Typically this will be the vertical measurement from the GPS antenna to the cutting edge, and will allow the App to compute the true ground elevation when you are working. Measure from the GPS antenna (typically from the vertical centre of the casing) to the cutting edge. Enter this in Settings in the App.
It is also possible to use this setting to calibrate the incoming GPS elevation to a known benchmark from a previous survey where you aren't using a fixed RTK base station. This is important when implementing an imported land levelling design because the target elevations in the design will be based on the original survey - if the base station has moved then your incoming GPS measurements will probably be out by several feet. Whenever you pre-survey a field with a mobile RTK base station it is very important that you leave a benchmark in the field to calibrate. A benchmark could be a stake or mark on the ground that you record the elevation of during the survey. To calibrate Ditch Assist to this original survey benchmark do the following:
- Stop with your implement directly on top of the benchmark
- Lower the cutting edge so it is resting on the ground on top of the benchmark
- In the Ditch Assist App, go to Settings and enter 0 in the GPS to Blade Height/Calibration Factor box
- Go back to the main screen, and read off the incoming GPS elevation from the GPS STATS panel on the left of the screen
- Subtract this height from the benchmark height, and enter the resulting value into the GPS to Blade Height/Calibration Factor box in settings
- Go back to the main app screen and verify that the elevation shown in GPS STATS matches the benchmark elevation
Example calibrations to a benchmark:
- Current GPS reading is 428.5ft
- Benchmark elevation was 420.25ft
- Difference is +8.25ft (99")
- Value to enter into GPS to Blade Height/Calibration Factor is 99 inches
- Current GPS reading is 988.25ft
- Benchmark elevation was 1000.75ft
- Difference is -12.5ft (-150")
- Value to enter into GPS to Blade Height/Calibration Factor is -150 inches (note the ' - ' must be entered here)