Dual GPS setups

Split from this topic: Front to BAck Dual Antenna - #82 by kareldew. The idea is you can share experiences and hardware setup for the dual GPS code from Matthias here: https://github.com/mtz8302/AOG_GPS_ESP32

Here is my rough test setup with the ESPduino, I had no problems, just had to switch the two F9P’s in place again (my bad). Roll, heading very accurate, quick and for now stable too. So the NTRIP stream making the ESP32 reboot was a faulty unit or a bug that happens with the ESP32 dev kit. Some thoughts:
-my previous remark of varying GPS rate was due to interference by a second computer screen
-is there a way to check position accuracy? Or is this not included in PAOGI sentence? Now it always reads: ‘PPS: 10 Hz’.


With the PAOGI sentence the same fix quality flag is send, as in gga. The esp only passes it over without doing anything with it.
The ntrip reboot bug may be caused by too large ntrip packet. Please check the packet size coming from port 2233 with Wireshark and post it here. I’ll check if it will fit in the reserved variable.
A good indicator for accuracy is the gps antenna distance in comparison to the real antenna distance. Could be seen in a debug message. This check is suggested by ublox, see manual

Here is the output from Wireshark, the list is arranged with heighest length on top.

I mean in AgOpenGPS on the main screen, there is no way to check accuracy on position as it always reads ‘PPS’. Only if roll or heading go to 0° you know something is going wrong?

The fix Quality Flag on UBX pvt is not the same as GGA. I discussed today with Brian. We will find a solution.
Is the esp crashing with the code from yesterday, when starting NTRIP? I changed from int to unsigned int.

When valid NTRIP is send to the f9p, the no RTK light will turn off. The one at the other f9p will be allways off, as it gets NTRIP from the other f9p

I am not using the ESP32 dev kit anymore so I can’t test the new code with it. The code from 16/2 looks to be working fine with the ESPduino.
Here is another way to mount the modules in a block. However the M3 nuts don’t fit well with the xbee headers and the header on the ESPduino.

Sure one thing to remember for starters, is that on both simpleRTK2b boards you should connect the 3.3v out pin and the IOREF pin. If the wifi network is x.x.1.x style of IP numbers, you only need to change wifi info and antenna distance in the ESP code and set 2233 as port in the ntrip settings in AOG. When you have for example x.x.0.x wifi network, also change module number x.x.1.x to x.x.0.x in the UDP settings in AOG. Set UDP On and it should work.

The ESPduino should also be a ESP32. For flash setting I use ESP32 Def kit.
Even, if you don’t need Wi-Fi, as you connect via USB, turn it on. An access point will be created. You can log in and change settings using your browser and the Webinterface. The ip to access it is send to USB at startup. You can see it in serial monitor

Will this work with ardusimple’s heading kit. Ubx-nav-relposned out uart1 and ubx position out of uart2. This would be with the ardusimple sitting on top of the espduino.

Get my 3 f9p boards tomorrow… Ouch got some £s into this now!
Thinking of roof bar build now… Would the position be best forward of the rear axle, at the front of the cab?

Maybe the front part of the cab will be ok. The steering works the better the nearer to the front wheels

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What to do with 4m spare aerial cable on ublox antenna that came with starter kit?
Put reciver in roof bar with esp32 and coil up spare cable or put electronic’s in cab?

I’m rushing a bit to build it before spring weather arrives. To give an idea this is a 160 cm long rectangular alu extrusion profile with 12x12 cm ground plates for the antennas. Attachment points on the tractors are mostly 90 cm apart so the idea is to attach it there with fly bolts or something. The excess ANN-MB cable I’ll stuff in the profile I guess.

Snap on the rush before spring!
Very similar idea, but I am using folded steel U section!
It was the stuffing bit that was concerning me, with possibly signal problems.

In my first version I put the Antenna on the electronic box. With the dual Antenna I glued them at the edges to the roof, but I should have put a ground plate under them. Not so easy, if the area is not flat.


Almost ready. The idea is that it’s mobile for use on different tractors. Stuffing the cables in the profile will be difficult. Contents piling out of the box again as if I don’t know better.
@MTZ8302 looks like we’re using the same box. I see you only use one wifi antenna for the RUT955, that will help a bit.

See you guys have the router in the roof box…mine is in the cab, so I can use cat5 for other things (including computer connection).

Hello Matthias, curious enough I’m again facing the Ntrip reboot issue (pbuf…). Now with the ESPduino which worked fine a month ago. I’ll do some more troubleshooting and respond back. It’s not due to power supply or ntrip packet size which I have checked again. v309 or v4 same.

Edit 20/3: doesn’t work with all connections checked, reuploaded config files, switched the two F9P’s in place again to be sure, tested all RX/TX combinations in the webpage. Sure I am missing something as I’m the only one facing these problems? It is with v4, latests ESP code and a ESP32 ESPduino device.

To give an idea with the extra antenna cables in the box it only just fits together with one wifi antenna.

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Hello @kareldew, making the idea exactly what we had, super! Glad I found this topic. Have an F9P with XBEE and a Base on the farm myself, only stopped because the heading and roll were a problem. (we work at very low speed, and the machine must immediately know an absolute position).
A mobile GPS bar with an ESP32 and the code of @MTZ8302 seems a very nice solution. Before I order an extra Zed-F9P, would you like to know if you have any tips that I should pay attention to? Does it work well with AOG v4? Does this solution only work with NTRIP from AOG, or can he also get the info from a Base via XBEE?

Thanks in advance!

Well the box is 200x120x75 mm which is at the lower limit for the contents in my case. A one meter antenna cable would suffice. First time I used riveting to attach a corner to the profile, which is actually very simple and effective. The reasoning for the box behind the profile is that it’s less top-heavy and the corner takes the impact of whatever might touch the roof and not the box. In that respect the antennas and the ground planes are the weakest parts, I imagine they will get bent one day by branches.

I did not test with v4 yet but Matthias and Brian are working hard on the integration of both, I can only applaud their efforts. I have to check the connections again so I can test my setup hopefully this weekend.

new Dual GPS code on GitHub. Hope it solves the jumping bug. Please report if it is not working.



Hello together.

Thank you two for the big effort in dual GPS. Today I tested V4.1 with the new code from 9days ago. It works really great except the jumping issues. For me it seems like the heading is lost some time and then a wrong heading (a few degrees off) is there for about 5 seconds. The tractor instantly turns sharp to the left or right. After stopping the tractor and wait a short bit, the correct heading comes back and we can start again. In 2 hours it happens maybe 5 times, so quite hard to screenrecord. I will try again the next days.
Can I help in any way? Record data? Or is it not possible to drive and record at the same time?