GPS Recommendations

I’m planning my second Autosteer build and basically starting with a empty tractor. No GPS fitted.

Chasing opinions on what would be suitable. Current setup is a Trimble FM750 giving 2.5cm accuracy. Is there a suitable receiver out there that will provide AOG with the same level of accuracy?

Ardusimple simpleRTK2B is popular here. Running on RTK like your FM750.

Cheers buddy I’ll do some reading. I don’t have RTK on the Trimble. It’s just running as a light bar.

But you mentioned it gives 2.5 cm accuracy. Did you mean it is RTK capable (2.5 cm or even less) but you have been running it on lower accuracy?

Ok well as far as I know it’s <1m accuracy as is… I could be wrong? I’ll have to physically measure two passes. It’s rtk compatible but no corrections are applied to the unit.

Not really important here but with SBAS (free correction signal) you should reach 30 cm pass to pass accuracy (probably one sigma confidence within 15 minutes). Absolute accuracy hardly reaches 1 metre but could be close.

Anyway, I was just assuming you would already have an RTK base or some other RTK correction source but this assumption turned out to be wrong. You could purchase another simpleRTK2B receiver to build a base if you want to reach sub-inch accuracy.

On that topic I’ve considered a RTK base.

What id like to know and nobody seems to be able to tell me. I have on the fm750 physically measured 16.5m implement width, and also physically measured pass to pass and reading 16.5 meters. That is spot on! Can’t ask for much more!

With the ardusimple gps. How accurate is it, out of the box, no corrections? Would it be adequate to replace the fm750 as a GPS receiver?

WAAS can give you pretty good pass to pass accuracy. But over time it will drift, especially relative to your starting position. RTK is as much about repeatability as it is about pass to pass accuracy. Year after year RTK can take you back within an inch of where you were last year, for example. And as you work across your field, and then return to the start location, it will be spot on. With WAAS you won’t get that. RTK might be overkill for you, but it’s actually quite cheap with the F9P-based receivers, so if you’re going to do a DIY job, you might want to put up a base station and just do RTK.

With the latest firmware, the ArduSimple board will resolve using WAAS or EGNOS (and probably whatever you have in Australia). So it should be as accurate as your Fm750 without any special corrections.

On your Fm750, are you sure you don’t have at least Rangepoint RTX enabled on it? If so, that’s a cut above what the Ardusimple can do without a base station.

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I use WAS for section control when spraying in tramlines. We normally have small fields, so drift after some time is no problem. When interrupting the field (fluid empty) and coming back hours later, the overlap or gap between the lines recorded before might be 0,5 m or more. There should be no gap/overlap when using tramlines.
When doing the field at once, the mismatch is about 0,1m I guess

I’ve just purchased as Reach RS+ from MapGear. They’re located in Cairns (QLD) and I found them to be very helpful, unlike the response I got from Novatel, Trimble and private GPS installers in Australia.

I think the best thing is that it should be ready to go straight out of the box, only a DB9 to Usb converter needed to connect to AOG. Corrections can be connected via N-TRIP or LoRa.

Let me know if you need a blank PCB or a few parts, I’ve collected a few extra.

The helpful people selling you the Rearch RS+ did not mention that it does not have the performance of your old Trimble receiver or that of the simpleRTK2B!

You would need the Rearch RS2 to have dual frequency support. RS2 has advantages over the simpleRTK2B but those come with a steep price. On that route you could have selected the OEM solution for your new empty tractor.

The SimpleRTK2B is a bare board. As they say, some assembly required. Specifically you need a power supply, and enclosure, and a means of getting corrections into it. Either a radio modem, or a Bluetooth to serial adapter.

And for a base station you need another one, either with a radio to transmit corrections, or a micprocessor board to communicate the corrections over an internet connection.

If you have the skills to do these things, or know someone that can do them nearby, then yes the SimpleRTK2b boards are the way to go compared to a Reach RS+.

The Reach RS+ may work okay for you . The built-in radios don’t reach very far. And I personally had very little luck getting an actual RTK fix out of them. They would get to float RTK very easy (roughly 0.5m accuracy), but getting to 2cm was an exercise in frustration. But others on this forum have had good luck with them.


New sprayer built and finally working. It’s fitted with Trimble GFX 750 and Ez Pilot - and Dealers not wanting to talk to either clients or installers. Never buying another Trimble.
AOG is more than capable of replacing the Trimble operations



Now we need to reverse-engineer the canbus messages that the 750 uses to turn the Ez Pilot steering wheel. I have an EZ-Steer and it’s on my list of things to do to sniff the can bus on it. Hopefully once this is documented, then AOG via an ESP32 or similar device can control it directly using only canbus messages.


What about an AG-Leader electric steering wheel? I assume they’re much like the Trimble system.

My truck above, has the Trimble for guidance/display and the section/switching rate is all on an Arag ISO bus system.
Pretty much autosteer + section + nozzle all automatic. It won’t do a u-turn! Apparently UTurn on the Trimble systems is an extra and only available for a machine with hydraulic steering.

An idea further to yours above. What if AOG was compatible with an ISO Bus rate controller… if you could make it drive one of those electric steering wheels, I’d even change the dc motor setup in my other sprayer.