Getting started with simple AB Line, no boundary system using ArduSimple simpleRTK2B

Wondering if anyone would be willing to provide input/help for a beginner. I want to build a simple AB line manual steer system for guidance while spraying pastures on my ranch. The pastures are between 40 and 200 acres. I always start spraying a particular pasture and finish that particular pasture within several hours. I do not have access to a free RTK station and I don’t want to build one and I cannot get Internet service in the Tractor due to poor cellular data service. It seems to me that if all of my spraying projects are no-boundary, manual steer, simple AB line created by the first pass across the field with the tractor, and if the job is finished within 2 to 4 hours, that RTK drift correction would not be necessary so long as accuracy within roughly 20cm is acceptable. The reason 20cm accuracy is acceptable is because I have end-of-boom spray nozzles that spray a lighter application rate that “fades” over around 20cm and I intentionally overlap passes by around 20cm to ensure coverage. I intend to use the ArduSimple simpleRTK2B (simpleRTK2B Basic Starter Kit IP67 - ZED-F9P Evaluation kit) receiver and antennae connected to a Panasonic ToughPad FZ-G1 tablet running Windows 10. Any input would be greatly appreciated. My main question is whether or not RTK drift correction would be required in my specific scenario of jobs that typically last 1 hour to 4 hours maximum (from the time the initial AB line is manually created by driving) with a goal of a minimum of 20cm accuracy. And by-the-way, since this might make a difference, all of my operations are on my ranch, which is flat. And all of my fields are rectangle or triangle shaped and therefore I don’t need to do curved AB lines. Thanks in advance!

I don’t know if you can do it without RTK. Maybe something else other than F9P(someone else might be familiar with). F9P alone AB Lines can go 100cm off in few hours… I had case where it drifted off and came back but you can’t rely on that…

Uprishaa, the F9P is advertised as being accurate within 1cm with RTK correction. I am a beginner, but based upon my readings, drift is caused by the movement of the satellite constellation relative to the antenna, and the changing of satellites as some disappear beneath the horizon and others come up above the horizon, which is something that occurs over time. Thus my wondering if a project of short duration would be impacted less compared to a project of longer duration, or a project influenced by boundary lines or AB lines set up in advance, or a project involving substantial elevation changes through the project. I don’t understand how one single-antennae 1cm accuracy receiver/antennae would have more drift compared to a different single-antennae 1cm accuracy receiver/antennae when not using RTK correction. I am a beginner and I my knowledge is very limited, but my statement above is based upon my readings. Am I missing something about different single-antennae receivers? I could purchase a different model, but it seemed to me that the more expensive models simply had functionality that I didn’t think I needed, but were not “more accurate” without RTK correction.

You are right. Neither am I an expert but I have experience that is worth more than something you read on internet. You mentioned that your job can be done within 2 - 4h
and thats big time difference. In practice AB Line drifted about 20-30cm in one hour… If overlap is not a problem to you, try it… my location and your location also could have different drift times, maybe for you it will work better than for me. Lets wait for some more answers here…

I don’t think satellite “drift” is as much of an issue as changing atmospheric conditions. The satellite signals are “bent” in the atmosphere in unpredictable amounts according to the air/weather conditions, a longer path causes errors in your position. A base station calculates these errors (because it can assume it’s stationary) and sends the error data to the rover to use for it’s own position calcs. It’s been said that the F9P is not the best receiver for non-RTK use but in your spraying application I think it might still work fine. What you will see after coming back to resume work is an offset from your last spray pass. Simply line up with your previous pass and snap/nudge the AB line to your “new” position and then continue spraying.

For many years we used an Outback S1 receiver on WAAS (a type of free SBAS correction in North America) and it worked well without RTK. It still has the standard amount of position deviation but very reliable and simple to operate.

1 Like

20 cm is tight to drive regardless. That is 10 cm each way. My dad uses a cheap Amazon plug in GPS and does ok with it. But it does have quite a bit of drift. My f9p without corrections is far better. But it definitely depends on the day. Numerous people run mobile base stations with a radio link. But I would say give it a try without it. Likely more accurate than you can drive.

1 Like

Thank you m_elias! I did not realize that some of the error was changing atmospheric conditions. I appreciate your input!

Thank you KentStuff! We have been using old-style foam marker for tracking, with no guidance system.
It is not super accurate and you are right that we are unable to drive a super straight line, which is one reason I use the end-of-boom side-spray nozzles with a “fading” spray pattern and utilize a small overlap. So I am hoping to have sufficient accuracy to do better than the foam marker method.

One follow-on question based upon KentStuff stating that many people use a mobile base station with a radio link. I was wondering if anyone had a recommendation on this and could advise on how far the tractor could be from the base station using a radio link. I was under the false impression based upon my readings that the RTK base station had to be connected to the Internet and I therefore assumed that the moving tractor doing the work would need to be connected to the Internet, which is an impossibility due to our poor cellular data service on the ranch. The ranch is 2,500 acres and the buildings are located on one side (where I have electricity, buildings, etc.). I was wondering if anyone knew how far the radio link would reach. Completely across the ranch from where our buildings are is as far as around 2 miles. Any chance there are systems that utilize a radio link that would communicate via radio that far? And if so, if anyone has any advice on which hardware I should purchase that would be great. I could always swap out to different hardware since I am early in this process. Thanks in advance for any input!

Out of the box it will be better than the old foaming method. That is what my dad switched from.

That kit includes a F9P receiver board designed for the XLR (1W) base station radio and a 2nd F9P with LR (20mW) radio for the rover/tractor and antennas for each. Generally the rover does not need to send any data back so it’s only listening which is why the base station has the higher power output. Once the base station F9P is configured, it only needs power to operate although the higher the transmitting antenna is the better so whether you’d want/need a RF extension cable depends on your installation options. The base’s GPS antenna does not need to be in the same spot as the transmitter radio (XLR) but it does need a good clear view of the sky. The rover will also receive better if its antenna is on the sprayer’s roof so either it also needs a RF extension cable or use a long USB cable to put the F9P on the roof in a box.

Thanks so much m_elias! This is very helpful! If the radio signal will transmit far enough to reach the far side of my ranch at around 2 miles I think this is an excellent solution at a low cost. Because I have already purchased the simpler stand-alone F9P receiver and it has already shipped, I think I will go ahead and build with this hardware and see how it works. If drift and/or atmospheric conditions impact are an issue with accuracy in my situation I can then purchase then swap out the hardware and utilize this radio transmitter solution. I really appreciate your input!

I hate to even post this here, but my dad can’t justify the higher priced GPS. I can not make him understand the cost difference. He is old school and basically uses the AOG just to get him on the right line and heading. He doesn’t drive the light bar. Just sets point and finds a spot at the other end of the field and drives straight. He is just as happy as he can be that he only paid $20 for his GPS. It is far better than fooling with the foamer. We spray hay fields and sometimes there are stripes of not sprayed field. But typically he sets his boom at 25ft for a 30ft boom and has good coverage. This is the GPS he has. You might buy a couple as we have had some that were better than others.

You will not be disappointed in your purchase.

KentStuff, while that super low cost solution might put a dot on a map, I think it would not be very efficient compared to the AgOpenGPS software on a tablet with a formal AB line and lightbar for steering, and the more accurate (but still low cost) F9P receiver. You mention that you have tried to talk your dad into better technology. I’m sure that the cost savings in herbicide alone will offset the cost of the AgOpenGPS / F9P solution. And the lightbar steering assistance with the AgOpenGPS seems like it would improve driving and save money on overlap and missed strips. I could not cost-justify the $4,000+ USD “out of the box” solutions by Trimble and others for my simple needs with hay and cow pasture as a “crop”. But now that I know about the dual antenna solution mentioned above at only around a +$650 cost increase compared to what I have already started with, to provide 1cm accuracy, I think I would have spent the extra money for the more accurate solution if I had known about it before I ordered the other hardware. Because more accuracy in terms of guidance and better driving (lightbar) does save money on herbicide compared to doing overlapping swaths. At any rate, I will see how good the simple solution I have purchased the hardware for already turns out to be, and it is nice to know that I can swap out for a more accurate radio-based RTK correction solution for a relatively low cost if needed. In the end, it is all about trying to get better coverage for the herbicide cost, and with the cost of herbicide for a 2,500 acre property, it is not difficult to save the entire cost of a low-cost system in a single year. This chat group has been super helpful and I appreciate your input!


Yes. I totally agree and have stated the same. Old school is not always the best. Wishing you well with your journey. And Welcome to the Forum!!!


For something as simple as that you can 100% do it with just a fp9 without rtk. I had issues with rtk last year and seeded 1/2 my acres you absolutely wont be able go for lunch and come back but non rtk pass by pass isnt that bad,

1 Like

I think you posted already but an fp9 receiver and antenna is ALL you need for the most basic guidance. Wont roll compensate and wont autosteet but it will map pass to pass just fine.

1 Like