IMU and Compass error with lost of GPS signal

Fire Fox · Mar 19, 2020

I took a flight today and everything was perfect on the preflight check and home point was updated. This was my 4th take off for the day but then when I got about 100 meters away I got and IMU heading error with a Compass error and weak GPS signal but there were 17 satellites then another compass error and an aircraft signal too weak error and she switched to Atti mode. So I turned her around and headed back but then as she was nearly back GPS was back and everything was fine and I continued to fly like normal and back out over the same area I was at no more problems. Has anyone experienced this does it mean I should recalibrate everything even though it was working fine after the problem?

Thomas B · Mar 19, 2020

@sar104 ... would flight logs help OP to understand?

sar104 · Mar 19, 2020

Thomas B said:
@sar104 ... would flight logs help OP to understand?

Definitely. It was likely a yaw initialization problem but the logs would be required to confirm how and why that happened.

slup · Mar 19, 2020

Thomas B said:
@sar104 ... would flight logs help OP to understand?

Yup that's the only way ... otherwise we only fall into irresponsible and depraved speculation.

@Fire Fox ... go here --> Flight log retrieval and analysis guide and read under point 3. Attach then the mobile device TXT & DAT logs here.

sar104 · Mar 19, 2020

slup said:
Yup that's the only way ... otherwise we only fall into irresponsible and depraved speculation.

@Fire Fox ... go here --> Flight log retrieval and analysis guide and read under point 3. Attach then the mobile device TXT & DAT logs here.

Irresponsible and depraved are fine, but speculation I cannot abide.

Fire Fox · Mar 19, 2020

I think you should see the flight record here http://app.gomailsend.com/wb.php?p=gdh5/f6kf/rs/6xn/d02p/rs

sar104 · Mar 19, 2020

Fire Fox said:
I think you should see the flight record here http://app.gomailsend.com/wb.php?p=gdh5/f6kf/rs/6xn/d02p/rs

For me that directs to a different URL that reports the linked site to be a known phishing website.

Fire Fox · Mar 19, 2020

sar104 said:
For me that directs to a different URL that reports the linked site to be a known phishing website.

I am trying the instructions there but my ipad does not seem to work like the say it does with itunes

Fire Fox · Mar 20, 2020

sar104 said:
For me that directs to a different URL that reports the linked site to be a known phishing website.

I think you should be able to see the flight log now on this file. It looks like it was a yaw error That caused it. Not sure what causes that and how to prevent it from happening again

Fire Fox · Mar 20, 2020

Fire Fox said:
I think you should be able to see the flight log now on this file. It looks like it was a yaw error That caused it. Not sure what causes that and how to prevent it from happening again

Fire Fox · Mar 20, 2020

33400	2020-03-19 15:23:02	-26.0912688074995	28.1504675907304	70.866144	5187.8683792664	25.0089892	202.428484168	16	5	11.258	5188.8526312664	71.850396	25.0089892	202.428484168	-19.685072	-15.434886	-0.223694	216.3	-4.3	4.2	1684	1024	1024	1024	216	41	3.733	3.732	3.725	9.118	109.94	5187.8683792664	70.866144	6	P-GPS
33500	2020-03-19 15:23:02	-26.0912772459139	28.1504581156336	70.866144	5187.8683792664	24.9866198	206.600400312	16	5	11.258	5188.8526312664	71.850396	25.0089892	206.600400312	-19.461378	-15.65858	0	216.3	-3.9	4.4	1684	1024	1024	1024	216	41	3.733	3.732	3.725	9.118	109.94	5187.8683792664	70.866144	6	P-GPS
33600	2020-03-19 15:23:02	-26.0912854423806	28.1504492211898	71.194228	5188.1964632664	24.941881	210.612539548	16	5	11.258	5188.8526312664	71.850396	25.0089892	210.612539548	-19.237684	-15.882274	-0.223694	216.3	-3.3	4.4	1684	1024	1024	1024	216	41	3.733	3.732	3.725	9.118	109.94	5188.1964632664	71.194228	6	P-GPS
33700	2020-03-19 15:23:02	-26.0912934684469	28.1504397118562	71.194228	5188.1964632664	24.8076646	214.673235216	16	5	11.39	5188.8526312664	71.850396	25.0089892	214.673235216	-19.237684	-15.65858	-0.223694	216.3	-3.4	3.6	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
33800	2020-03-19 15:23:02	-26.0913017077482	28.1504303524399	71.194228	5188.1964632664	24.494493	218.78609624	16	5	11.39	5188.8526312664	71.850396	25.0089892	218.78609624	-19.01399	-15.434886	-0.223694	216.2	-2.9	3.6	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
33900	2020-03-19 15:23:02	-26.0913088506508	28.1504214718815	71.194228	5188.1964632664	24.1813214	222.479993996	16	5	11.39	5188.8526312664	71.850396	25.0089892	222.479993996	-18.790296	-15.211192	-0.447388	216.1	-3.1	3.5	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34000	2020-03-19 15:23:02	-26.091316238836	28.1504126492301	71.194228	5188.1964632664	23.8905192	226.249679156	16	5	11.39	5188.8526312664	71.850396	25.0089892	226.249679156	-18.790296	-14.763804	-0.223694	216	-3.6	4.1	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34100	2020-03-19 15:23:02	-26.0913233911705	28.1504031833839	71.194228	5188.1964632664	23.8905192	230.056109724	16	5	11.39	5188.8526312664	71.850396	25.0089892	230.056109724	-18.566602	-14.54011	-0.223694	215.8	-3.7	2.4	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34200	2020-03-19 15:23:02	-26.0913306218266	28.1503942355726	71.194228	5188.1964632664	23.4431312	233.810046852	16	5	11.39	5188.8526312664	71.850396	25.0089892	233.810046852	-18.566602	-14.316416	0	215.6	-2.8	1.6	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34300	2020-03-19 15:23:03	-26.0913375278883	28.150384844914	71.194228	5188.1964632664	23.1746984	237.542002352	16	5	11.39	5188.8526312664	71.850396	25.0089892	237.542002352	-18.566602	-13.869028	0	215.7	-2.4	2.4	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34400	2020-03-19 15:23:03	-26.0913444427044	28.1503759896088	71.194228	5188.1964632664	22.8615268	241.19423344	16	0	11.39	5188.8526312664	71.850396	25.0089892	241.19423344	-18.342908	-13.645334	0	215.7	-2.6	3.1	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error. Aircraft GPS signal too weak. Home Point not updated.
34500	2020-03-19 15:23:03	-26.0913509277677	28.1503667507367	71.194228	5188.1964632664	22.7273104	244.7834724	16	0	11.39	5188.8526312664	71.850396	25.0089892	244.7834724	-18.342908	-13.42164	0	215.8	-3	3.5	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34600	2020-03-19 15:23:03	-26.0913574570204	28.1503579920195	71.194228	5188.1964632664	22.4141388	248.311687736	16	0	11.39	5188.8526312664	71.850396	25.0089892	248.311687736	-18.119214	-13.197946	0	215.7	-3.5	3.8	1684	1024	1024	1024	216	41	3.735	3.735	3.727	9.118	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34700	2020-03-19 15:23:03	-26.0913634927373	28.150348870945	71.194228	5188.1964632664	22.2799224	251.755585484	16	0	11.39	5188.8526312664	71.850396	25.0089892	251.755585484	-18.119214	-12.974252	-0.223694	215.7	-3.7	4.1	1352	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.1964632664	71.194228	6	P-GPS	Yaw Error
34800	2020-03-19 15:23:03	-26.091369940646	28.1503397328188	71.522312	5188.5245472664	22.033859	255.336950428	16	0	11.39	5188.8526312664	71.850396	25.0089892	255.336950428	-18.119214	-12.526864	-0.223694	215.7	-3.9	4.7	1149	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	6	P-GPS	Yaw Error
34900	2020-03-19 15:23:03	-26.0913752311349	28.1503311776534	71.522312	5188.5245472664	21.7206874	258.46621562	16	0	11.39	5188.8526312664	71.850396	25.0089892	258.46621562	-17.89552	-12.30317	-0.223694	215.8	1.9	4.4	1077	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error. Compass Error. Exit P-GPS Mode
35000	2020-03-19 15:23:03	-26.0913809316789	28.1503226244716	71.522312	5188.5245472664	21.4075158	261.727698664	16	0	11.39	5188.8526312664	71.850396	25.0089892	261.727698664	-17.671826	-12.079476	-0.223694	215.7	0.3	1.7	1040	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35100	2020-03-19 15:23:03	-26.0913859807933	28.1503139179394	71.522312	5188.5245472664	21.1614524	264.82284312	16	0	11.39	5188.8526312664	71.850396	25.0089892	264.82284312	-17.671826	-11.632088	-0.223694	215.7	-1.9	0.6	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35200	2020-03-19 15:23:04	-26.0913912326164	28.1503056101948	71.522312	5188.5245472664	21.027236	267.915690988	16	0	11.39	5188.8526312664	71.850396	25.0089892	267.915690988	-17.671826	-11.408394	-0.223694	215.6	-2.7	0.4	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35300	2020-03-19 15:23:04	-26.0913958533849	28.1502971819059	71.522312	5188.5245472664	20.915389	270.843840688	16	0	11.39	5188.8526312664	71.850396	25.0089892	270.843840688	-17.671826	-11.1847	0	215.5	-2.4	-0.1	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35400	2020-03-19 15:23:04	-26.0914007337664	28.150289097435	71.522312	5188.5245472664	20.6693256	273.794956268	16	0	11.39	5188.8526312664	71.850396	25.0089892	273.794956268	-17.671826	-10.737312	0	215.5	-2	-0.8	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35500	2020-03-19 15:23:04	-26.091404995235	28.1502809595204	71.522312	5188.5245472664	20.5574786	276.574155832	16	0	11.39	5188.8526312664	71.850396	25.0089892	276.574155832	-17.671826	-10.513618	0	215.5	-1.7	-1.2	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35600	2020-03-19 15:23:04	-26.0914095836951	28.1502731392167	71.522312	5188.5245472664	20.6469562	279.39961524	16	0	11.39	5188.8526312664	71.850396	25.0089892	279.39961524	-17.89552	-10.289924	0	215.5	-1.6	-1.4	1024	1024	1024	1024	216	41	3.743	3.745	3.739	7.246	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error. IMU heading error. Please restart the aircraft.
35700	2020-03-19 15:23:04	-26.0914135428203	28.1502653053709	71.522312	5188.5245472664	20.4232622	282.043644196	16	0	11.171	5188.8526312664	71.850396	25.0089892	282.043644196	-17.89552	-9.842536	0	215.4	-1.4	-1.6	1024	1024	1024	1024	215.9	41	3.748	3.748	3.743	6.78	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35800	2020-03-19 15:23:04	-26.0914178505106	28.1502577511037	71.522312	5188.5245472664	20.5127398	284.745415936	16	0	11.171	5188.8526312664	71.850396	25.0089892	284.745415936	-18.119214	-9.618842	0	215.5	-1.2	-1.3	1024	1024	1024	1024	215.9	41	3.748	3.748	3.743	6.78	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
35900	2020-03-19 15:23:04	-26.0914215212058	28.1502503421761	71.522312	5188.5245472664	20.5127398	287.23426116	16	0	11.171	5188.8526312664	71.850396	25.0089892	287.23426116	-18.119214	-9.171454	0	215.6	-1	-1.3	1024	1024	1024	1024	215.9	41	3.748	3.748	3.743	6.78	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error
36000	2020-03-19 15:23:04	-26.0914254490648	28.150243211225	71.522312	5188.5245472664	20.1995682	289.751977776	16	0	11.171	5188.8526312664	71.850396	25.0089892	289.751977776	-18.119214	-8.94776	0	215.6	-0.7	-0.9	1024	1024	1024	1024	215.9	41	3.748	3.748	3.743	6.78	109.94	5188.5245472664	71.522312	1	Atti	Yaw Error

Unfortunately this is all I could fit on the post

Fire Fox · Mar 20, 2020

sar104 said:
For me that directs to a different URL that reports the linked site to be a known phishing website.

slup · Mar 20, 2020

Yeah ... your story are backed up by the log. At 35sec the navHealth suddenly plums from max to 0 & the AC switches to ATTI mode ... no uncommanded movements can be seen & then at 73sec the navHealth goes to 2 & at 86sec fully restored to 5. During this whole period between 16-17 satellites were locked.

To pinpoint a probable reason for this the mobile device DAT log is needed ... look here under point 3 how to retrieve --> Flight log retrieval and analysis guide , the correct log have FLY213.DAT in the end, attach it then here.

The markers placed when the AC have switched to ATTI mode ... the yawing is commanded, exiting that you continued to climb with this happening.

And the messages:

Fire Fox · Mar 20, 2020

slup said:
Yeah ... your story are backed up by the log. At 35sec the navHealth suddenly plums from max to 0 & the AC switches to ATTI mode ... no uncommanded movements can be seen & then at 73sec the navHealth goes to 2 & at 86sec fully restored to 5. During this whole period between 16-17 satellites were locked.

To pinpoint a probable reason for this the mobile device DAT log is needed ... look here under point 3 how to retrieve --> Flight log retrieval and analysis guide , the correct log have FLY213.DAT in the end, attach it then here.

The markers placed when the AC have switched to ATTI mode ... the yawing is commanded, exiting that you continued to climb with this happening.

View attachment 96923

And the messages:

View attachment 96924

Thanks for this. Yeah I decided to climb to see if it would improve the problem. But it only improved when I got close to where I was. I will try get the mobile device dat log. Not sure how to get it with just my iPad as my pc is not recognizing I’m iPad for some reason

sar104 · Mar 20, 2020

Fire Fox said:
Thanks for this. Yeah I decided to climb to see if it would improve the problem. But it only improved when I got close to where I was. I will try get the mobile device dat log. Not sure how to get it with just my iPad as my pc is not recognizing I’m iPad for some reason

How did you get the txt log? It's basically the same process.

Fire Fox · Mar 20, 2020

sar104 said:
How did you get the txt log? It's basically the same process.

I got the text log eventually by using the Airdata app but the Airdata app only shows the flight logs it doesn’t reflect anything about the mobile device dat log not sure if it can be extracted from the app

slup · Mar 20, 2020

Fire Fox said:
I got the text log eventually by using the Airdata app but the Airdata app only shows the flight logs it doesn’t reflect anything about the mobile device dat log not sure if it can be extracted from the app

Now I'm an Android guy ... can't stand all restricted thing's with iOS, but surely you must have some sort of file explorer in your device from where you can find the log. Then either Bluetooth it or mail it to your computer ... or upload it to some web storage. Or actually go into this web site with your device web browser & pick that log and attach it to a post here ?

sar104 · Mar 20, 2020

slup said:
Now I'm an Android guy ... can't stand all restricted thing's with iOS, but surely you must have some sort of file explorer in your device from where you can find the log. Then either Bluetooth it or mail it to your computer ... or upload it to some web storage. Or actually go into this web site with your device web browser & pick that log and attach it to a post here ?

For some reason the file explorer under iOS doesn't see the DJI GO 4 directory. It does see the DJI Fly directory, which suggests that something needs to be updated in the GO 4 app to make it accessible.

Fire Fox · Mar 20, 2020

sar104 said:
For some reason the file explorer under iOS doesn't see the DJI GO 4 directory. It does see the DJI Fly directory, which suggests that something needs to be updated in the GO 4 app to make it accessible.

is this file the correct file?