GPS Signal / Interference problems

Decided I would start a thread on here rather than cluttering telegram,

As many will know, I have been having some real teething issues getting my dual antenna system up and running… I have been having all kinds of issues with erratic position jumping around, erratic heading issues, causing the autosteer to go quite crazy / very un consistent. In the process of tuning / tweaking / playing, I have many times, got the system to a point where I thought it was perfect…but then to find a few minutes later its less than ideal, if not un-useable again.

In the process of diagnosis, I have been swapping back to my old sf3000 receiver (serial connected), and also a single F9P with rover config on it…including with, and without RTK correction, but what I am finding, is it makes no difference which setup I use, weather it be Dual (ESP), single F9P, or SF3000, I am getting the same erratic behaviour, that sometimes will work perfectly, and others (most of the time) be completely useless…

Today i plugged i my Deere greenstar monitor, as it happens just to look at the serial settings, but made a discovery, it seems that out of the blue, the SF3000 just totally looses GPS signal… either to 0, or very low (15-35%)… occasionally it will climb back up, but then just beep at me / drop right off again… This prompted me to wonder, do I have a bigger problem going on here?

So out of interest at this point, I disconnected everything new, and went back to my old system, that I have been using for 5+ years, which is the SF3000, serial into my tablet, with FarmerGPS…and am finding that the signal can be erratic in there also…

So I am thinking something is causing huge interference with my GPS, which is quite likely whats causing all of my troubles all this time! But I cant figure out what it could be… have ruled out alternator as still seems to be the same with engine off vs engine on…and have unplugged everything that I can think of that is aftermarket electrically on the tractor…

Does anyone have any ideas what could be causing this chronic interference?

The behaviour I get is just very jumpy position / heading, when on the line, it will constantly jump about 20-30 cm left / right, playing havoc with the system…

WAS wires haven’t got damaged anywhere? Touching something they shouldn’t? Clutching at straws tbh but they have a direct line into your system…

The AOG settings anomaly does suggest a bigger issue still though. Possibly also causing the lag. You are defiinate your install and your tablet are ok? I know you’ve tested a laptop too but…

Are there barns or factories nearby with metal roofing, I have seen reflections from metal roofs even 500 m away,causing lost rtk.

Trimble units cause a lot of gps trouble if you don’t have a good power source. Night and day difference from using cigarette plug to going straight to battery. Version 4.3 is working good for me.

What happens if you connect the F9P to Ucenter away from the tractor do you get stable position information? Then try AOG just with a laptop and F9P away from the tractor.

All looks good to me… Although have barely used it / put everything in conduit, so be unlikely to just yet. Signal from WAS seems good and stable to…

Hm, I have the greenstar system, and also all my AOG setup connected to the D pin power supply socket in the cab…but then always have had it like this…Worth me taking a feed from battery post you think instead?

Hm havent tried…Would be a bit of a pain as don’t have a spare antenna and have routed cables etc inside roof of tractor now…

I did try just driving with U center open the other evening to see if i saw the same jumping about, but couldnt find anywhere easy in the software to see that small level of jitter very easily?

Ooohh that is not a good idea!! My 716 even interferes with my ancient muller accord maize drill box through the d plug.

Scatter pattern window. If that’s what it is called :grimacing:. Set at lowest distance.

I use the deviation map in ucenter set at 0.1m it gives you a good visual of your signal while stationary

Plus you need your rtk using the ntrip client in ucenter.

I’ve been powering my F9P through usb and had problems with jumping when connecting to it through a usb hub shared with the nano. The pcb is powered straight from the battery. Using separate usb ports on the computer seemed to solve that. Although yours is WiFi connected, I also think it could be some issue with the power supply.

Sounds like next logical step will be to run a new cable from battery into the cab for all this kit. Am i still ok to use the same feed for the sf3000 etc as well as the tablet / nano etc do you think? Whats weird is I have had the sf3000 connected to the D plug for 6+ years, and never once had an issue with it…

I’m not sure what the best setup would be for the dual gps. Would be good to know how Matthias powers the stack. Is a feed taken from the pcb board? In my basic setup I just power the tablet from the cigarette lighter and the tablet powers the F9P then the pcb has a feed from the battery.

I’m powering the 2 f9p and the ESP with a self build 12v to 5v converter just as the one on the pcbv2

“Deviation map”. The proper name I was looking for!:grimacing:

Something on your tractor could have lost it’s noise suppression though. Possibly not affecting the thing itself but really upsetting other stuff.

Power requirements for the simpleRTK2b 120mA (600mW = 120mA @ 5V) without anything on the xbee socket

Besides multipath, harmonics of other equipment can interfere as well. Seen this happen with 2 radio’s in the 70cm band.

Also look for any transmitter that has harmonics (multiples the transmit frequency) in the gps frequency range. GPS Frequency Bands - everything RF


Spent the afternoon starting from scratch to try and figure out what on earth is going on…and after much messing, it seems it WAS the USB hub plugged into the tablet causing the grief, even with nothing plugged into it, just having it plugged in, instantly causes the greenstar / starfire to loose signal and play havoc with things…

Will update my other thread with news on dual heading / other problems though!

That is also a possibility on mine. :thinking:
When it was plugged into a noisy power line it caused huge grief as I said on telegram. Maybe it is still causing some intermittently even now it’s got clean power.

CF-D1 has enough USB ports to do without it too.