The BIG GNSS (GPS) Issue -- The Constructive Thread

[mcde]

And if that was what caused the signal acquisition to be so bad. why haven't they simply changed that back to what it was somewhere in the last three months?

I edited my post to address this. If it was so simple they would have restored it to the "pre-December" version. It seems they don't want to for reasons only they are aware of. Let's not forget that we can only speculate and that we do not have access to the vast amount of data they have.

 

[Meta4]

It seems they don't want to for reasons only they are aware of.

Or it's just not that simple and the problem is something entirely different from the speculation that it was about greater accuracy..

 

[Meta4]

this is corroborated by the fact that this issue is not affecting all users, i.e. it seems to be related to region.

I haven't seen anything that suggests the problem is only affecting users in a particular region.
Are you aware of anything on this?

 

[mcde]

I haven't seen anything that suggests the problem is only affecting users in a particular region.
Are you aware of anything on this?

Perhaps I should have written my previous post differently. This is only from what I have read so far, it seems that users in EU are not affected as much, or the last firmware update has resolved the issue for them. But then again, we are only speculating.

 

[GrimtheViking]

Perhaps I should have written my previous post differently. This is only from what I have read so far, it seems that users in EU are not affected as much, or the last firmware update has resolved the issue for them. But then again, we are only speculating.

I am in the UK, and after the last update mine is still between 5-9mins...

 

[oztx]

I think the data we've collected suggests there's some hardware difference between different M3 production dates. As I noted way upthread The BIG GNSS (GPS) Issue -- The Constructive Thread some of us have never had the problem and my acquisition times have always been around a minute. Yes, a bit slower than other DJI aircraft, but never the multiple minute times others have reported.

I've flown this M3 in North America and Asia with no acquisition time change at any launch point, so I discount the hypothesis that the problem is location-based.

And finally, I've flown using the RC-N1 and RC Pro and that doesn't make a difference either.

I'm placing my bet on either a firmware revision or SKU change in the GNSS chipset and unintended consequences that come from that.

 

[mcde]

If I remember correctly there are people that did not have this issue before the December update though.

 

[GrimtheViking]

If I remember correctly there are people that did not have this issue before the December update though.

I had no Gps problems before the December update, HP locked in seconds.

 

[oztx]

If I remember correctly there are people that did not have this issue before the December update though.

My understanding is that nobody reported this as an issue before the December update.

 

[ianwood]

I think the data we've collected suggests there's some hardware difference between different M3 production dates.

To the best of my knowledge, there is no data showing any hardware changes. If you are referring to the KA variant M8030, it is believed all Mavic 3 have that variant. Furthermore, the KA variant has no material difference from the KT variant (used in Air2 / Air2S) with respect to the function of GNSS.

 

[oztx]

To the best of my knowledge, there is no data showing any hardware changes. If you are referring to the KA variant M8030, it is believed all Mavic 3 have that variant. Furthermore, the KA variant has no material difference from the KT variant (used in Air2 / Air2S) with respect to the function of GNSS.

We know there have been hardware changes (for example the oval zoom lens), but until more of us crack our M3s open, we won't know about any internal changes that might be the culprit. And I've certainly worked with chipsets of different revisions or SKUs that were functioned identically in the lab, but not in the field.

Anyway, I'm willing to be wrong -- this is just where I've placed my bet.

 

[Mad_Angler1]

While there were not specific reports of long acquisition time on early firmware there were a fair number of reports of poor GPS performance with stability and flight and I actually mentioned this in my review. I think people should start to think that way of what DJI may have addressed in later firmware.

There is no evidence there is more than one module and im going to say now i am strongly of the opinion the hardware is absolutely fine and comparing M3 GPS to MA2 is not apples for apples.

I have a LOT of data already and im starting to come to some conclusions and while im not ready to spell it out yet im hoping to by end of the weekend/early next week.

I am also going to be clear that while I can confirm somethings I will be giving an opinion on the issue and that is as always going to be open to debate but it will be fact based on actual data. One thing for sure is people need to stop talking about sat count as it close to means bugger all once you are over 8. Positional accuracy and HDOP and PDOP are the key data.

 

[DelBeachFlyer]

We know there have been hardware changes (for example the oval zoom lens), but until more of us crack our M3s open, we won't know about any internal changes that might be the culprit. And I've certainly worked with chipsets of different revisions or SKUs that were functioned identically in the lab, but not in the field.

Anyway, I'm willing to be wrong -- this is just where I've placed my bet.

They changed the camera mid-run on the M3? I missed that. From round to oval? Why would they do that? Now I need to go look to see which one I have (drone isn’t nearby at the moment).

I wonder what would happen if someone desoldered the KA and installed the KT on an M3. If acqusition time magically fixed itself we would know the root cause… well, closer to it anyway.

 

[bogdi1988]

Any possibility that their algorithms are not properly taking advantage of the local time zone and of daylight saving time and due to that they are calculating incorrect data that is leading to a delay in locking in the GPS signal?

I've had some various Android based car stereos and none of them were ever coded correctly to handle time zones and things would always be inconsistent. Just throwing that out.

 

[oztx]

They changed the camera mid-run on the M3? I missed that. From round to oval? Why would they do that?

Yeah. Details here: Mavic 3 telephoto lens image quality comparison - Oval v.s. Round

 

[Suren]

Has anyone tried making changes to the GPS receiver using drone hacks? It shows values for GPS but i dont know how to read this thing, maybe we can also get into what Dji broke with Airsense and fix via drone hacks if it is as simple as changing some values.

 

[ianwood]

Has anyone tried making changes to the GPS receiver using drone hacks? It shows values for GPS but i dont know how to read this thing, maybe we can also get into what Dji broke with Airsense and fix via drone hacks if it is as simple as changing some values.

View attachment 146133

I'm not sure the configuration for the GPS will be in the DJI parameters but it might be. I do know that DJI likes to program the GPS on each boot. Search for GPS or GNSS and cut and paste here all the parameters that can be configured with their default values. Or just drop the whole list.

The one most interesting to change would be GLONAS for Beidou. I doubt that is the issue but it would be good to rule it out. There might be another setting for minimum elevation or DOP. I don't suggest changing those.

 

[Suren]

I'm not sure the configuration for the GPS will be in the DJI parameters but it might be. I do know that DJI likes to program the GPS on each boot. Search for GPS or GNSS and cut and paste here all the parameters that can be configured with their default values. Or just drop the whole list.

The one most interesting to change would be GLONAS for Beidou. I doubt that is the issue but it would be good to rule it out. There might be another setting for minimum elevation or DOP. I don't suggest changing those.

 

[Suren]

I'm not sure the configuration for the GPS will be in the DJI parameters but it might be. I do know that DJI likes to program the GPS on each boot. Search for GPS or GNSS and cut and paste here all the parameters that can be configured with their default values. Or just drop the whole list.

The one most interesting to change would be GLONAS for Beidou. I doubt that is the issue but it would be good to rule it out. There might be another setting for minimum elevation or DOP. I don't suggest changing those.

I cannot find anything about GNSS but these were all i could find about GPS, not sure if it makes sense to you.

 

[Raffaello_IZ0QWM]

It’s actually really important that hearsay and incorrect information is not allowed to become “fact”

The reason is in future when other DJI drones or other manufactures use this chipset people will look at it and say ohh it’s the bad one beciase that guy said it is or it’s badly designed.

Hearsay and rumours quickly become fact online. The OP post is very cleverly written in such a way that it’s hard to go back with “facts” as such. It’s a classic example of “prove me wrong, ohh you can’t.” Well we can actually.

I have spent half the day talking with one of the main hardware designer of one of the flight controller manufactures. While I can’t share docs as it’s all under NDA with Ublox they are more than happy with what DJI appear to have done with the module. Antenna is good, ground plane is good, battery in place and no issues with any of the chipsets chosen. Nothing alarming initially. I have ordered a Mavic 3 GPS module my self tonight for £100 and that will be here this week and I will also do some digging my self and sharing findings.

My hardware guy did comment on the use of BeiDou though and it was not exactly good.

To the the fantastic user who hooked his upto Ucenter can you share any info you will save me an hour on connection pin out ect.

Edit:

Dang just found you thread, ok your image confirms no external flash. For peoples info that QFN unpopulated in not flash. It’s not the right pinout. Too many infact, also the M8030 has 2Mb internal storage that’s more than enough for most GPS usage as as been stated.

I personally am not expecting any issues with the module it’s self and tbh I’m leaning on interfearance. We are seeing similar issues with HDZero wiping out the GPS too. While everything is speculation the module overall looks fine. What is really possible it’s it’s a packaging issue in the drone. A wire in the wrong place or clock signal from one of the CPUs. Silly mistakes do happen.

I hope everyone is well.

I can confirm that interference could be a problem. As I said in another post the EMI problems could explain the problems in some drones and not others.
To mitigate via firmware, they may have kept off some component that they think might be annoying or have lowered the speed of the serial between the GPS chip and the FC.