H520 not arming - GPS Speed Accuracy too low

[deezx]

We have a YUNEEC H520 with E90 camera, which is not arming anymore. It was working in the past.
Now there is always an error message and a GPS warning:
Warning: Preflight: GPS Speed Accuracy too low

Sometimes additionally:
Warning: Preflight: GPS horizontal pos error too high

We have tested it in an open field with 16 GPS satellites available and HDOP 0.8 and VDOP 1.0, which should be enough for arming.

When trying to change between "Angle" mode and "Manual" the error message changes, but, the GPS warning persists:
Critical: Not arming: Switch to a pilot flight mode first
Critical: Not arming: No GPS! Wait or switch to indoor mode
Critical: Switching to this mode is currently not possible

When trying the "indoor" mode, the H520 works well, it can bee armed and remains stable in the air (calibration performed), but when disabling the "indor" mode, the GPS problem is back. No arming possible.
Firmware of ST16, H520 and E90 have been updated to the newest version available (after update the H520 was flying, but this is some months ago).

Anybody who had the same problem?
May the GPS module of the H520 be defective?
It shows enough satellites, has green symbol on the remote control, but the "Warning: Preflight: GPS Speed Accuracy too low" and "Critical: Not arming" persists in all test cases (including keeping the drone active on the ground with good GPS satellite coverage for much more than half an hour). Changing batteries of H520 and ST16, resetting, repeating calibration had no effect.
Any ideas?

 

[WTFDproject]

We have a YUNEEC H520 with E90 camera, which is not arming anymore. It was working in the past.
Now there is always an error message and a GPS warning:
Warning: Preflight: GPS Speed Accuracy too low

Sometimes additionally:
Warning: Preflight: GPS horizontal pos error too high

We have tested it in an open field with 16 GPS satellites available and HDOP 0.8 and VDOP 1.0, which should be enough for arming.

When trying to change between "Angle" mode and "Manual" the error message changes, but, the GPS warning persists:
Critical: Not arming: Switch to a pilot flight mode first
Critical: Not arming: No GPS! Wait or switch to indoor mode
Critical: Switching to this mode is currently not possible

When trying the "indoor" mode, the H520 works well, it can bee armed and remains stable in the air (calibration performed), but when disabling the "indor" mode, the GPS problem is back. No arming possible.
Firmware of ST16, H520 and E90 have been updated to the newest version available (after update the H520 was flying, but this is some months ago).

Anybody who had the same problem?
May the GPS module of the H520 be defective?
It shows enough satellites, has green symbol on the remote control, but the "Warning: Preflight: GPS Speed Accuracy too low" and "Critical: Not arming" persists in all test cases (including keeping the drone active on the ground with good GPS satellite coverage for much more than half an hour). Changing batteries of H520 and ST16, resetting, repeating calibration had no effect.
Any ideas?

Has anything happened between the last time the system worked properly and the first time it did not? Things like firmware updates, long storage periods, crash, hard landings, maintenance, modification, or anything else you know of?

The error message is common with the latest firmware, but it should clear by itself within a couple of minutes when GPS is acquired. If the H520 has been in storage for a long time, it may just need to stay powered on with a good view of the sky for about 15 to 30 minutes to update the GPS almanac.
If that does not clear the problem, then an actual GPS or IMU issue would be suspected. You may benefit by checking the connectors on both modules. If you have another HPlus, H3 or H520 available, you can swap GPS modules to determine if the GPS module is defective.
You can also swap IMU modules to see if that helps. The IMU is actually more likely to be the issue.

 

[deezx]

Has anything happened between the last time the system worked properly and the first time it did not? Things like firmware updates, long storage periods, crash, hard landings, maintenance, modification, or anything else you know of?

The error message is common with the latest firmware, but it should clear by itself within a couple of minutes when GPS is acquired. If the H520 has been in storage for a long time, it may just need to stay powered on with a good view of the sky for about 15 to 30 minutes to update the GPS almanac.
If that does not clear the problem, then an actual GPS issue would be suspected. You may benefit by checking the connector on the GPS unit. If you have another HPlus, H3 or H520 available, you can swap GPS modules to determine if the GPS module is defective.
You can also swap IMU modules to see if that helps. The IMU is actually more likely to be the issue.

Thanks for the fast response!
There was a long storage period. Nothing else happend.
> If the H520 has been in storage for a long time, it may just need to stay powered on with a good view of the sky for about 15 to 30 minutes to update the GPS almanac
We checked this, that is why the H520 was kept in good GPS conditions with 14-16 satelites for long periods of time (about 40 minutes)... but did not help. It was repeated on an other day.
> You may benefit by checking the connector on the GPS unit. If you have another HPlus, H3 or H520 available, you can swap GPS modules to determine if the GPS module is defective.
I did not check this yet. I have a Tyhoon H (not the Plus), and took out the GPS module to test it, but I have trouble to open th H520 (the little plastic clips next to the screws fit very tight and I am afraid of breaking them)
> You can also swap IMU modules to see if that helps. The IMU is actually more likely to be the issue.
Did not try this yet. This was also my first thought, why I repeated the calibration of compass/gyroscope a couple of times. But in Indoor mode, the H520 is very stable in the air. Shouldn't it be unstable, if there is a problem with the IMU? Also the message "GPS Speed Accuracy too low" does not point to the IMU... but I may be wrong (if the firmware "thinks" the GPS speed is wrong due to comparing with wrong values from the IMU)

 

[Pier2162]

Hi Deezx.
I had similar trouble with my H480, solved replacing the gps battery. It's very cheap, and easy to find and replace. Hope this can help your bird to lift in the air again.

P.s....it's a good practice to power on the drone and fly at least every 2~3 months.

 

[h-elsner]

The H520 GPS module backup battery is a MS412FE (btw. different to Typhoon H which has a MS621F).

It would also be good to have a look on the related TLOG file from ST16 flight logs.

 

[Johnny$]

We have a YUNEEC H520 with E90 camera, which is not arming anymore. It was working in the past.
Now there is always an error message and a GPS warning:
Warning: Preflight: GPS Speed Accuracy too low

Sometimes additionally:
Warning: Preflight: GPS horizontal pos error too high

We have tested it in an open field with 16 GPS satellites available and HDOP 0.8 and VDOP 1.0, which should be enough for arming.

When trying to change between "Angle" mode and "Manual" the error message changes, but, the GPS warning persists:
Critical: Not arming: Switch to a pilot flight mode first
Critical: Not arming: No GPS! Wait or switch to indoor mode
Critical: Switching to this mode is currently not possible

When trying the "indoor" mode, the H520 works well, it can bee armed and remains stable in the air (calibration performed), but when disabling the "indor" mode, the GPS problem is back. No arming possible.
Firmware of ST16, H520 and E90 have been updated to the newest version available (after update the H520 was flying, but this is some months ago).

Anybody who had the same problem?
May the GPS module of the H520 be defective?
It shows enough satellites, has green symbol on the remote control, but the "Warning: Preflight: GPS Speed Accuracy too low" and "Critical: Not arming" persists in all test cases (including keeping the drone active on the ground with good GPS satellite coverage for much more than half an hour). Changing batteries of H520 and ST16, resetting, repeating calibration had no effect.
Any ideas?

Well I see I'm not the only one after that last major update my H520E is now completely useless and this comes right after buying a new dual charger and extend batteries. I'm still taking big losses with this aircraft.

 

[WTFDproject]

Well I see I'm not the only one after that last major update my H520E is now completely useless and this comes right after buying a new dual charger and extend batteries. I'm still taking big losses with this aircraft.

Are you interested in trying to get it back into working condition? You can start a new thread and describe what it is doing/not doing. The H520E has features way beyond the birds most of us fly but we can at least try to help.

 

[deezx]

@all Thanks to all responses here!
The H520 is arming again. I have replaced the GPS module. Now everything is fine again.
I might test replacing the battery MS412FE in the non working GPS module, but this has no priority now. The non working GPS module is now put into safe place as a replacement part for future. Seems like it is necesarry to keep the drone busy and not storing it for long periods of time.

 

[Pier2162]

it is necesarry to keep the drone busy and not storing it for long periods of time.

This is a best practice that should be done every 3 months. I've and recommend this habit.