Benchmarks and calibration: do I need to calibrate today?
When you need a benchmark and when you don't, set one per field, and calibrate to it every time you come back to an older survey or design. The BM badge, the Calibrate Elevation window, drive-to-the-benchmark, calibrating to a survey or design point, and the Advanced options.
In the app BM badge › Calibrate Elevation
Two words, two different things. A benchmark is a spot you can drive back to (the field entrance, a culvert headwall, a fence corner) whose position and ground elevation the app has saved. Calibrating is telling the app what your elevation is right now by parking on something whose elevation it already knows: a benchmark, or an untouched point on an earlier survey or design.
You don't need either for most first jobs. You do need them every time you come back.
Do I need to calibrate today?
No benchmark needed
You survey and grade in one session on one base setup. The survey, the design and the grading all used the same base position, so the elevations already line up. Just grade. The app doesn't ask.
Calibrate first
You're coming back to a survey or design from another session: another day, a job that runs over several days, next year's cleanout, a design built from an older survey; or the base was moved, set up again, replaced or rebooted.
| Today's job | Calibrate? |
|---|---|
| Survey a ditch this morning, grade it this afternoon, base untouched | No. Same base setup. |
| The tablet or the app restarted at lunch, base untouched | No. After a restart the Calibrate Elevation window reads "Restored" in orange; if nothing moved, carry on. |
| Next spring's cleanout of the same ditch, from last year's survey or design | Yes. Park on the field's benchmark and calibrate before the first pass. |
| A three-day land forming job | Yes, every morning. The base was taken down or restarted overnight. |
| Day two of the same ditch | Yes. |
| The base blew over, was bumped, lost power or was moved mid-job | Yes, before you carry on. |
| Grading a design someone built from a survey taken last week | Yes. |
| Brand-new field, first survey | No calibration, but it's the moment to set the field's benchmark for next time. |
Why it matters
- Base set up again. Never quite the same as day 1, so raw GPS reads every spot 0.25 ft high. The shift can be any size, up or down; it's the same everywhere in the field.
- Calibrate on the benchmark. With the cutting edge resting on it, calibrating measures the shift. How to calibrate.
- Back in line. The 0.25 ft comes off every reading, so today's numbers match your survey and design.
An RTK base works out its own position each time it's set up, and it's never quite the same twice. Every elevation the rover reports shifts by that difference: it could be an inch, it could be a foot, and it's the same everywhere in the field. Grade last year's design on today's raw numbers and the whole ditch comes out too deep or too shallow by that amount.
Calibrating measures the shift once, on a spot whose elevation is known, and takes it off every reading for the rest of the session. You never see or type the number.
The BM badge
The BM badge in the stats bar on every Survey and Grade screen opens the Calibrate Elevation window. The line at the top of the window tells you where you stand:
| Status line | Meaning | Do |
|---|---|---|
Green Calibrated to benchmark "Field entrance" · 5 min ago | Calibrated in this session, and to what | Work |
Orange Restored from Oct 16, 2026 — recalibrate before working | The app restarted and put back the last calibration. It's applied, but nobody has checked it since: the base may have moved. | Recalibrate, unless you know the base hasn't moved since |
Grey Not calibrated — elevations are raw GPS | No calibration | Fine for a same-day job; calibrate before working an older survey or design |
On the badge itself: grey means not calibrated. Once a calibration is applied the badge turns orange, whether it was done today or restored after a restart, so open the window and read the status line to tell which.
1- BM, grey. Not calibrated. Tap to open Calibrate Elevation.
1- Restored. Last session's calibration, not yet checked today.
Set one benchmark per field
One benchmark per field, used for everything in that field, year after year. Pick a spot you'll find again in any crop and any season, that won't be cut, filled or driven into soft: a field entrance, a culvert headwall, a fence corner, a concrete pad. Set it the first day you work the field, before your first survey, while the base is untouched.
Park on the spot and lower the cutting edge
Drive onto the spot, lower the implement so the cutting edge rests on the ground, and stop. The GPS button in the top bar must read RTK in green.
Tap BM
Open a Survey or Grade screen. Tap BM, the small square in the bar across the top, between the Wi-Fi symbol and the spanner. The Calibrate Elevation window opens.
- BM. In the top bar.
Tap Manage benchmarks
Green writing with a small flag, near the bottom right of the window. If you can't see it, scroll down inside the window (how to scroll). The Benchmarks window opens: every saved benchmark with its elevation and how far away it is.
1- Manage benchmarks. Set, rename and delete benchmarks.
Tap Set Benchmark here
The wide light-blue button under the list. It stays grey until there's a GPS fix. A small window asks for a name.
1- Set Benchmark here. Saves the spot where you're parked.
Type a name you'll recognise next year
The app suggests "BM 1", "BM 2" and so on. Hold down the delete key to clear it, then type a name like "North 40 gate" or "Culvert east" (typing on the tablet). The name shows on the map flag and in every list.
- Name box. Replace the suggested name.
Tap Save, and hold still for 5 seconds
Tap Save at the bottom right of the small window. The app averages 5 seconds of RTK: Averaging GPS position...
. Keep the machine still.
- Save. Starts the 5-second average.
1- Saved. Green tick: calibrated to it.
Surveys, designs and jobs you save after this remember which benchmark they were aligned to. With Field Mode on, the benchmark also belongs to the field and the app prompts you to use it.
Coming back: calibrate on the benchmark
Every return visit, first thing, before you survey or grade. It takes under a minute.
Tap BM
Connect as usual and wait for RTK. On the Survey or Grade screen, tap BM in the top bar.
- BM. Grey or orange: either way, tap it.
Loading or resuming an older survey, design or job often asks Calibrate GPS?
first: tapping Calibrate there opens this same window. Its tip may suggest a zero cut/fill spot; if the field has a benchmark, use the benchmark.
1
2- Skip. Only if the base hasn't moved since that file was made.
- Calibrate. Opens Calibrate Elevation.
Tap your field's benchmark
Under CALIBRATE TO the window lists what you can calibrate to, nearest first: your benchmarks (blue flags), and the loaded survey or design if there is one. Tap your field's benchmark. Within about 165 ft (50 m) of a saved benchmark, the window opens straight on its card: go to the next step.
1- Your benchmarks. Nearest first. Tap yours.
Drive to it
A card opens and counts down as you move: Drive 104.7 ft to the benchmark
while you're more than about 10 ft (3 m) away.
1
2- Distance. Counts down as you drive.
- Calibrate Anyway (5s avg). Not yet: see the warning below.
Get onto the pin
Within about 10 ft the card turns yellow, Almost there — 7.9 ft to the pin
, and the button changes to Calibrate to … (5s avg) with your benchmark's name. Within about 1.5 ft (0.5 m) it turns green: On the benchmark — lower blade and calibrate
.
1- Almost there. Creep forward until it turns green.
Lower the cutting edge and tap Calibrate to … (5s avg)
First rest the cutting edge on the benchmark (or on the ground right at it). Then tap the orange Calibrate to … (5s avg) button and keep still while it averages 5 seconds of RTK.
1- Calibrate to … (5s avg). Tap when the card is green.
1- Averaging. 5 seconds. Don't move.
Check the green line, then tap Close
The line at the top turns green: Calibrated to benchmark "BM 1" · just now
. Tap Close and work. Today's elevations now match the survey and design.
1- Calibrated to benchmark. Green, with how long ago.
No benchmark? Calibrate on the old survey or design
Coming back to a job that never had a benchmark? With the old survey or design loaded, the window adds a Loaded survey or Loaded design row. Drive to a point on the run where the ground hasn't changed since the survey, lower the cutting edge and tap Calibrate.
1
2
3- Loaded design. With the distance to the nearest point on it.
- Calibrate. 5-second average on that point.
- Surveyed ground / Design grade. Which elevation to use at that point.
Surveyed ground (the default)
Use on ground that hasn't been touched since the survey: the bank beside the ditch, the uncut end of the run, a spot the scraper never reached.
Never on ground you've cut
Calibrating on cut ground with Surveyed ground raises every target by however much you've cut. On a stretch that's already finished to grade, switch to Design grade instead.
- The app refuses if you're too far away:
Too far from route — move closer
, or for a design more than 50 m (165 ft) off the line,Too far from the design line — move onto the run first
. - Once calibrated, set the field's benchmark (above) while you're there, so next time is a one-tap job.
- Land Forming designs can carry their own benchmarks: they show as Design BM rows and work the same way (Land Forming).
Advanced: typed elevation, zero, clear
Under Advanced at the bottom of the Calibrate Elevation window, for the rare cases. Each asks you to confirm.
| Option | What it does | When |
|---|---|---|
| Type an elevation, Set BM | Set your current position to 812.50 ft? This replaces the current calibration.One instant reading, no 5-second average. | A surveyor gave you the elevation of the spot you're parked on |
| Zero to current GPS | Makes raw GPS the reference (offset 0), discarding the current calibration | You want to work in raw GPS elevations |
| Clear BM | Clear the benchmark offset? Grading will use raw GPS elevations until you recalibrate. | Starting over. Only there once a calibration is applied |
1
2- Known elevation and Set BM. Type, tap Set BM, confirm.
- Zero to current GPS. Raw GPS as the reference.
The same offset is shown in the app's Settings, in the SURVEY box, on the Benchmark Offset row. Its Open calibration button opens this window.
Details, for support calls
Tap Details on the status line to see the current GPS elevation, the offset in use and where it came from. Support may ask you to read them out.
1- Current GPS Elevation and Offset. What support needs.
With Field Mode on
Field Mode ties benchmarks to fields and runs the routine for you: entering a field that has a benchmark asks Calibrate to this field's benchmark
(Go opens the drive-to card), and a field with none asks Set a benchmark for this field?
. Loading a file that was saved against the benchmark you're calibrated to asks nothing: it already lines up.
If something goes wrong
- Grade is off by the same amount everywhere: Grade off by a constant, The base moved
- You calibrated from too far away: Calibrated in the wrong place
- Calibrated on cut ground: Recalibrated on cut ground
- The
Calibrate GPS?
prompt and what to answer: Calibrate GPS? No RTK samples collected. Check GPS fix.
: RTK Float- Every calibration message: Error messages
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