fendt 724 loses gps signal

[ksp9000]

GPS with Topcon AGI-4 with RTK
At certain time a day GPS looses signal for 30 minutes, also accuracy is quite random time to time - from few cm up to half a meter. Quite annoying while seeding etc in one direction and randomly about half a meter will be not seeded and when coming back - same width is seeded (double) over.
Is someone faced this issue?

 

[Boysground]

Is this ntrip rtk. Is it a roaming sim? When was it last changed?

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[ksp9000]

yes ntrip rtk with roaming

 

[Boysground]

There have been issues with BT and EE, when BT bought EE they shut down the EE data signal last year. There were issues with the sat nav searching for the EE signal but it wasn’t to be found. I had a new sim last autumn which solved the problem. You can pull the fuse to reset the system, or get a new sim if it’s more than a year old.

I had similar symptoms but with Trimble ntrip varioguide

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[Northern farmer]

GPS with Topcon AGI-4 with RTK
At certain time a day GPS looses signal for 30 minutes, also accuracy is quite random time to time - from few cm up to half a meter. Quite annoying while seeding etc in one direction and randomly about half a meter will be not seeded and when coming back - same width is seeded (double) over.
Is someone faced this issue?

Do you mean GPS signal being lost or do you actually mean GPS accuracy being lost?

The receiver should see the GPS (and Glonass) satellites equally if the NTRIP correction signal is lost (may even report more satellites as the correction signal may not cover all the locally observed satellites).

Easy to check the RTK correction signal age from the screen menus. Should stay within a couple of seconds normally.

I've seen some odd behaviour lately that did not happen a couple of years ago. The AGI-4 starts to lose RTK fix even the correction signal is fine. It usually only goes for a couple of seconds, comes back for minutes but at times struggles more. Have not been able to figure out if it is some sort of interference from 4G/5G networks or something completely different. We do not have power lines or any sources for significant interference otherwise. Useless to ask from AGCO (at least at my place).

Is your NTRIP modem a 2G/3G modem or an older 2G only modem? If the RTK correction signal is not stable, it could be something like Boysground explained. I believe you only have 3G nowadays while at my place 3G is discontinued but 2G still provides perfect connectivity for the low bitrate RTK correction signal.

 

[ksp9000]

I have seen both, signal being lost completely for example at lunch time and 6hrs later and this happening every day. Also accuracy thingy seems to be more happening this year. I noticed "white" lines (not seeded) in dirt while on field and checked accuracy in menus, jumped from 0.3m to almost 0.5m with 9 satellites and signal being "green".

Afaik its 2G/3G modem. If its power lines i would not complain but its happening with out any interference on the field also.

 

[Northern farmer]

Sounds like your losing RTK and having only RTK float accuracy. I cannot remember for sure but I though your signal indicator should not be green but orange or something if RTK fix is lost. Or is it green on 5 bars (full RTK fix) and still green on 4 bars (no RTK fix). I would not drill if accuracy was not 5 green bars, i.e. full RTK (even if some members here claim even EGNOS being enough).

Do you know if your screen shows the number of GPS satellites only or both GPS and Glonass? There was a software release that only shows the number of GPS satellites (I still have that SW). 9 satellites is on the low side if it is GPS + Glonass. 9 is quite OK if it is GPS only (and the receiver actually makes use of a few Glonass satellites on top of those).

You could check GPS satellite availability e.g. from this website:

Trimble GNSS Planning

www.gnssplanning.com

The issues I've seen happen when the number of available GPS satellites is low. Should be sufficient but on the low side.

Who is providing your NTRIP signal? Are other users and other tractors fine in similar conditions? I run my own base and the base too has some parts of the sky partly obstructed by a couple of trees. Difficult to say if one or two GPS birds are blocked at the base and one or two at the field, making the total too low for RTK even if you started from 7 to 9 or so.

I have no problems with NTRIP connectivity. If I had, I would use a temporary repeater radio next to the field. Receive NTRIP corrections on a laptop and broadcast with a radio to make the RTK correction signal 100% perfect (if your NTRIP source allows that).

 

[Boysground]

I checked mine yesterday and was on 15 satellites. Coincidentally we were combining a field I always have issues in, for some reason I rarely have full ntrip connection over the whole 70ac. It will be fine and then the bars will drop from green to orange for a while and eventually go back green. I could see some slight wobbling with the drill rows in the stubble yesterday but no misses. I’ve discussed it with the dealer a number of times but it’s only this field. It’s on top of a hill I can see for 30 miles and there are no hedges and 1 tree. I’ve put it down to “one of those things “ the surrounding fields are fine.

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[Northern farmer]

I checked mine yesterday and was on 15 satellites. Coincidentally we were combining a field I always have issues in, for some reason I rarely have full ntrip connection over the whole 70ac. It will be fine and then the bars will drop from green to orange for a while and eventually go back green. I could see some slight wobbling with the drill rows in the stubble yesterday but no misses. I’ve discussed it with the dealer a number of times but it’s only this field. It’s on top of a hill I can see for 30 miles and there are no hedges and 1 tree. I’ve put it down to “one of those things “ the surrounding fields are fine.

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Sounds really odd. A pity they have not implemented real logging tools for post analysis at the factory.

The reason for accuracy change from "green to orange" is the lack of NTRIP correction, the correction data age too high? Just checking because the "orange" accuracy may occur even if the NTRIP correction was perfect.

I'd test with radio to be sure, perhaps a distant interferer that can be "seen" only at hill top.

 

[Boysground]

I have one phone mast within sight, it is odd as I don’t have the issue on adjacent fields