Learning Center

The receiver says RTK, but Ditch Assist shows DGPS

Some receivers, John Deere StarFire SF-RTK in particular, report a true RTK fix as DGPS. With the RTK Filter on, Ditch Assist then won't record survey points, won't calibrate and holds grading. Here is how to tell which case you have and what to change.

  • Full Automation Kit
  • Guidance Only Kit
  • DIG™ Kit

In the app Settings › SURVEY › RTK Filter

Ditch Assist® reads the fix type the receiver puts in every GGA message. Code 4 is RTK Fixed (green RTK), code 5 is Float, code 2 is DGPS (orange). With RTK Filter on (the default), anything other than RTK Fixed is refused for survey points, benchmark averaging and Auto Measure, and grading holds. That's right for a receiver that really has no RTK, and wrong for one that labels its RTK fix as DGPS.

Before you start

  • Sit where you can see both screens: the receiver's own display (for example the John Deere display) and the Ditch Assist tablet.
  • Know where your corrections come from: your own base, an RTK network, or a satellite service (SF3, RTX, TerraStar).

Time: 2 minutes.

Quick checks first

  • The receiver's own display says RTK while the Ditch Assist GPS badge shows DGPS.
  • The corrections come from your own base or an RTK network, not a satellite service.
  • You know where the switch is: RTK Filter, in the SURVEY box of the Ditch Assist Settings (steps below).

Find your symptom

Tap the line that matches what you see. Check tells you how to spot the cause. Fix tells you what to do, one step at a time.

StarFire on RTK, Ditch Assist shows DGPS and won't survey“RTK Filter is ON and this receiver reports DGPS. Turn off RTK Filter (Settings > Survey) to survey with it. Tap here to open Settings.”

That amber line sits on the card before a survey. You also see No RTK samples collected. Check GPS fix. when you calibrate, Auto Measure won't measure, and grading holds with HOLD — No RTK Fix.

The receiver reports its RTK fix as DGPS Most likely

Check: The John Deere display shows an RTK fix from a real base or RTK network, and the Ditch Assist GPS badge shows orange DGPS. John Deere StarFire SF-RTK is the known case.

Fix:

  1. Tap the small, underlined amber line under START SURVEY on the survey card. It opens Settings. (Or tap Settings, the fourth button down the right-hand column.)
  2. Scroll down to the SURVEY box, about a third of the way down Settings (how to scroll).
  3. Find RTK Filter, the fourth row in that box.
  4. Tap its switch on the right so it turns grey (off). The change takes effect straight away.
  5. Tap Survey, the second button down the right-hand column, to go back to your survey.
Settings screen scrolled to the SURVEY box: Recording Interval, Blade Height with Auto Measure, Benchmark Offset with Open calibration, RTK Filter with a green switch (on), and RTK Sensitivity with Low, Mid and High buttons.
  1. RTK Filter. In the SURVEY box of Settings.
  2. The switch. Green is on (the default). Tap it once to turn it grey (off).
The RTK Filter row in the SURVEY box of Settings with its switch grey (off), and the RTK Sensitivity row under it. 1
  1. RTK Filter, off. The switch at the right end of the row is grey.
The receiver's display also says DGPS, or no RTK

There's no RTK fix Most likely

Check: The receiver agrees with Ditch Assist: no RTK.

Fix: Leave RTK Filter on. Get the corrections working: see Stuck on Float, or RTK keeps dropping.

The receiver runs SF3, RTX, TerraStar or a similar service

Satellite services aren't RTK

Check: The receiver may call it RTK-level, but it's a satellite (PPP) correction. The badge may show DGPS or PPP.

Fix: These aren't endorsed for survey or grading, and turning RTK Filter off doesn't make them accurate: expect the blade to drift with the elevation. Use your own RTK base or an RTK network. See Correction sources.

Still not fixed?

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