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GPS Explanation - 5500 view thread with 500 posts initially
1558 29 3-28 03:40
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Snoopy2
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3-28 03:40
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ianwood
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Seems like you are more interested in how many views you get than what's actually true. The uBlox M8030 KT and KA variants have the same memory. Zero difference. The thread you reference does not exist. Prove me wrong. There is zero evidence of any issue with ephemeris being held in memory. Enough with this already.
3-28 08:13
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Tornado12
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I just read through this for the first time today, and there is a LOT wrong with this from a technical standpoint. Several elements of this doesn't even make sense from a technical stance. Because of that I would say this is most likely not true. For one, the UBX M8 GNSS chip is basically the same across all 3 variants. Flash memory would not be inside the chip, but external, and connected to the chip through IO. The chip could have some internal ROM but it would not be used how you describe here with all the other features of the drone. This just isn't how things work. I am NOT an expert or an electrical engineer, but I know a little about these things, enough to know this doesn't make a lot of sense. You also make the following statement:

"...Every time the drone had a cold start, it had to go through the process of downloading the ephemeris data, slowly, on a limited bandwidth, to a small pipeline..."

The drone does download this data, but I don't understand the language of "on limited bandwidth and to a small pipeline" We are talking about an ASCII text file here, that is extremely small. You talk about this thing as if the drone is having to move large amounts of data around and seem to suggest some kind of bottleneck. This just makes no sense. We are talking about miniscule amounts of data.

The summary of the issue suggested here is that the KA Variant of the UBX M8 chip doesnt have the memory to function properly versus the KT Variant of the chip, and because of this memory bottleneck, we are seeing manifestation of issues, most notably in the gps acquisition time. I just find this a little bit ridiculous. It just doesnt make a lot of logical sense. First of all, all my reading of the 3 variants, even the indepth product specification papers suggest they are essentially the same product. The M8 gnss chip is simply a single chip - it is not an entire pcb. This is a very tiny 5mm x 5mm chip. It has IO for external Flash memory, but as I said that would be external. So before we even get to the technical questions themselves we have to believe that DJI's entire Engineering team designed an inadequate gnss pcb module that was wholly inefficient, and didn't realize that they had made this mistake. If you can bring yourself to believe that, then you have to buy into this scenario that doesnt make a whole lot of technical sense....

I just cant buy this. It is too illogical. I still feel the most likely culprit here is firmware, or perhaps some integration with the Beidou constellation, but I still feel it has to be firmware. I am very puzzled that they haven't been able to fix it though. I wont rule out hardware problems, but so far there is just no evidence to go on to suggest that. All of the evidence still points to firmware, though I will admit if it is firmware it is puzzling that they didn't get it 100% fixed in this last update. The explanation here though makes even less sense though. Ill continue to follow the evidence. The above explanation feels like it was very made up by someone with very limited technical knowledge.
3-28 08:32
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Mad_Angler1
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Ok so the original thread was deleted and the same nonsense posted again.  Luckily I still have the posts ;).
3-28 08:57
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3-28 09:21
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Tornado12
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Snoopy2 Posted at 3-28 09:21
Good. Let's see how long it takes for them to fix this.
Facts remain:
(1) GPS was broken

Yes, we know gps is a little slow, and has been. I follow the evidence though. All evidence we have to go on suggests firmware still. If something new comes up that suggests otherwise I would love to read it. What you have shared above however is not it. Whoever gave you this information made it up. They had to, because it makes zero sense from a technical standpoint. It has the smell of someone who has very little technical knowledge trying to come up with some reasoning for the gps issue...So that is the first issue. You are right that I do not know the exact cause of the issue (none of us do). I am also however not making up fake reasons. We do have a body of evidence though, so I go off of that.

Where did you get this explanation of the issue? I would be really curious as to its origins, and of its intent. Is it possible the origin happens to also be someone who is obsessed with DJI, and obsessed over this issue? If so, that would further debunk this, as it would reveal motive. The lack of technical knowledge, the oversimplification of the design process things like the drone would have undergone by teams of experienced engineers, the motive, all of this feels cooked up and immature.

Its easy to get overly frustrated with things, and to buy into silly scenarios like the OP shared above when you have zero real world understanding of how things work. Even if the OP's post was technically sound, you would still be overlooking the vast amount of time and resources and expertise that goes into designing a drone like this. The odds of engineers making such a blunder, and missing it all through the R&D process, only for it to be found later by a troll with no technical knowledge on the internet is so slim to be almost zero. It suggests such a black and white, elementary view of how things function from its originator.

You just leveled a serious allegation here in this post, that I suspect has been totally made up by someone. You dont get to gloss over that and just go back to obsessing over the issue. No, you have to defend this now, or where it came from. I suspect this is why it was deleted the first time by DJI.
3-28 10:03
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3-28 12:08
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Snoopy2 Posted at 3-28 12:08
https://www.youtube.com/watch?v=EjmTLs3ofcs

His videos are always entertaining. I get a kick out of the way this guy flip flops on how he feels about his drones. Autel, dji.. you name it. Thanks for sharing !
3-28 12:32
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Snoopy2 Posted at 3-28 12:08
https://www.youtube.com/watch?v=EjmTLs3ofcs

Now you can see who it was who made the rather detailed statements about the hardware of the UBX hardware:
   Mad's Tech
He is a very experienced all-rounder regarding very different hardware topics, really...
3-28 13:04
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The Saint
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lol obviously if dji just moved on to a 3s and left original m3 owners behind, of course we would be angry.  but maybe the "s" was always planned and maybe it will include other stuff.  i mean, who cares what kind of gps chip is in the drone, they're all the same, right? lol
3-28 14:15
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Mad_Angler1
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All the M8030 models have the same internal basic layout of CPU and SRAM including the amount, the differences between the automotive KA variant and professional KT version is electrical characteristics more than anything, this is mostly for use in harsh environments such as vibrations and temperatures. Devices labels as automate grade will usually also comply with the electronics council automotive requirements such as ACE-Q100 Grade 1.

Automotive variants may have some other small changes but overall the performance remains the same as the professions and standard model in normal use cases.  They are more expensive due to the additional compliance but have no real features drawbacks as is being suggested.
It’s the same Ublox core being used.  

  
As for is DJI using SQI flash on the Mavic 3 it’s unknown at this time. That will be located under the metal shielding and not external to it.

There is an image being posted around of the Mavic 3 GPS module with the unpopulated IC area and people are asking is that the missing flash ?   The answer to that would be no as A: it’s external to the shedding and it’s also not the correct pinout for SQI Flash.  That’s a QFN package that’s not the same as the flash used.  


We don’t know yet if DJI have added flash for the GNSS as we need to see below the shield , it’s worth nothing that the M8030 does not require external SQI flash to store ephemeris  and almanac data for normal use it is still recommended for certain applications.  For instance when using Glonass it’s advised to have SQI flash for additional configuration data. That would be located under the shielding can and not off to the side of the PCB.  But today we don’t know what the situation is.  Regardless we have seen DJI not use flash in the past and they have not had issues and I would not be expecting the frequently of them we are seeing.

The fact there is a battery backup is a very good signs they are retaining ephemeris and almanac data regardless. This is all looking fine.  

As for that missing chip it is very likely a second compass option, IC for controlling beacon or accessory that DJI have chosen not to fit. It is not unusual for them to do this and almost every model has unpopulated areas on the board.  It’s absolutely normal.  Remember DJI often make multiple variants and even design it with features they never use due to costing and marketing. This has been the case for many years.

In the end the Ublox GNSS chipset is fairly simple in the sense it handles GPS and that’s passed out over Uart, USB,I2C or SPI to the flight controller. DJI choosing the Automotive variant changes nothing major over the non automotive other than costing them more.  

Further more DJI would not use GPS memory on board the Ublox chip or SQI flash to store data for smart features like was added in the last big update.  Any GPS data needed for smart features will be stored in the companion SOCs running the smart shots in ram on DJI side of the Mavic 3. The Mavic 3 is certainly not short on CPU power or ram compared to older models that for sure.

Right now there is way too much hearsay on this and there needs to be far more actual testing.  The problem with misleading information like saying the automotive module version is the cause is when people see that in other devices or future ones they will think it’s bad.  The simple fact is the module chosen is absolutely fine.

That’s not to say though DJI don’t have issues or that there is not something wrong because there clearly is. This all could be as simple as bad components in the supply chain, internal interference from poorly placed wiring or just a firmware bug.  It may be more than one issue and not everyone has the same one.  Some of this may still be a results of the shift to BeiDou and people having poor coverage but we need proper data on that, we need to see results from ublox u-center at same time and location to see what’s going on.  There needs to be proper data not just assumptions.

It’s very simple overall, DJI have years of designing GPS, but that’s not to say something has not bitten them here, but I’d not expect great public acknowledgements of issues, they never been their way. They will quietly fix it if they can or they won’t and they will move on. History is littered with some DJI products with unresolved issues, I own half of them my self .

Right now if your having this issue my advice is to open a ticket. Send logs and even ask for replacements. The fact some still have issues after DJI have released firmware to address it shows is a far more complex issue than just a simple bug.  They are clearly trying but software can’t fix bad hardware and if it is an issue with your specifically you are better trying to get it changed.  I’m not saying they won’t be able to fix this in firmware but if it was something simple they would have nailed it by now.

Hopefully this explains things a little better.

Stay safe

Mad.
3-28 14:16
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Mad_Angler1
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A final note on another change the with the Mavic 3, DJI switched form Glonass to BeiDou with the M3 for the first time on any of their consumer models.

This all may in the end all may not be an gps issue at all simply be normal based on the performance of BeiDou, actual user usage outside of China is very limited and we don’t have massive experience to go by. I have been given some interesting comments from people in the know on the choice to use BeiDou and there is a reason most are still not transitioning and would rather stay with an ageing Glonass.
3-28 14:47
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3-28 14:51
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Mad_Angler1
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Snoopy2 Posted at 3-28 14:51
Except the  UBX-M8030 supports Glonass which is directed by the DJI firmware. And if that was the cause - DJI could have supplanted one with the other quite easily. Moreover, at any time, while you may only be reading 2 or 3 Beidou Satellites, there are plenty of GPS and Galileo satellites available. Finally, one would expect the latest M30 model to suffer the same performance issues if that were the case as they also use Beidou (GLONASS is only implemented when RTK is used). Notwithstanding the prevailing understanding that this only became and issue after the December firmware.That explanation doesn't make sense.
How do you know the M30 is not, it’s not in customers hands yet and review samples were VERY limited.  

And as for Novembers firmware some were having the issues before then. Much less noise but noise non the less.

As for switching to Glonass, If DJI had a desire to do that that could. Don’t assume just because it may fix an issue they will.  That’s a very political issue more than anything.  DJI have chosen to switch to BeiDou now when they could have at any time in the past. That reasoning will not be for performance I suspect.  Also note close to no others in the drone and other gps space are using BeiDou.  There is a reason for that.  
3-28 14:58
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3-28 15:11
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Mad_Angler1
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BeiDou is not widely used in drones or most GPS.  Most systems are limited to 2 and that’s GPS and Glonass.  While yes other systems use it it’s not remotely as widely used as the other.

Further more as for the pre November firmware, perhaps they were not using BeiDou then.  Again speculation but anything is possible.

However let’s  put some facts on things shall we, i have spend £90 and I will have a Mavic 3 GPS Unit in hand this week.  

Rather than all this nonsense with hear say , half truths and peoples believe let’s put it though it’s paces on the bench and see what’s really going on the module from an RF and design point of view .
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3-28 15:23
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nevermind.
3-28 15:34
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Mad_Angler1 Posted at 3-28 15:23
BeiDou is not widely used in drones or most GPS.  Most systems are limited to 2 and that’s GPS and Glonass.  While yes other systems use it it’s not remotely as widely used as the other.

Further more as for the pre November firmware, perhaps they were not using BeiDou then.  Again speculation but anything is possible.

Wow that's awesome! Nothing like getting down into the science of an issue. Can't wait to see what you come up with! Thanks for doing that.
3-28 15:35
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3-28 15:35
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Snoopy2 Posted at 3-28 15:35
Further more as for the pre November firmware, perhaps they were not using BeiDou then.  Again speculation but anything is possible.

I was talking about Pre-December firmware. I never said anything about "Pre-November" firmware. The drone was only released in November.

At least they included a bigger battery that will guarantee the same ol' 30 minute flight time after waiting for GPS lock.
3-28 16:54
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3-28 17:36
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Mad_Angler1 Posted at 3-28 15:23
BeiDou is not widely used in drones or most GPS.  Most systems are limited to 2 and that’s GPS and Glonass.  While yes other systems use it it’s not remotely as widely used as the other.

Further more as for the pre November firmware, perhaps they were not using BeiDou then.  Again speculation but anything is possible.

Good too see someone who appears to have micro solder experience here sharing some insight. You are doing what I maybe would do, but just don't care enough...To buy a module and just take it apart and study it. I really do not expect you to find anything alarming or out of the way here. I just cant see anybody as competent as DJI messing up the GPS module in a drone like this. DJI have years of experience in this area. I see a high level of competence in their design of drones. Granted anyone can make mistakes, but the kind of silly mistake as originally detailed in the OP, not having enough onboard memory to function properly, is just not where the issue is going to be. If this is ever determined to be a hardware problem, it will be much more complex than that. That is like saying DJI would have sold a car with just 3 tires and didn't realize it.

I would be intrigued to see what you find nonetheless.  Perhaps you could do a video breaking the board down. It could help a lot of people understand these things better and perhaps not get whipped up into believing made up issues. There is so much ignorance now circling this issue, in large part because of some folks sheer obsession with it.
3-29 04:58
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Tornado12 Posted at 3-29 04:58
Good too see someone who appears to have micro solder experience here sharing some insight. You are doing what I maybe would do, but just don't care enough...To buy a module and just take it apart and study it. I really do not expect you to find anything alarming or out of the way here. I just cant see anybody as competent as DJI messing up the GPS module in a drone like this. DJI have years of experience in this area. I see a high level of competence in their design of drones. Granted anyone can make mistakes, but the kind of silly mistake as originally detailed in the OP, not having enough onboard memory to function properly, is just not where the issue is going to be. If this is ever determined to be a hardware problem, it will be much more complex than that. That is like saying DJI would have sold a car with just 3 tires and didn't realize it.

I would be intrigued to see what you find nonetheless.  Perhaps you could do a video breaking the board down. It could help a lot of people understand these things better and perhaps not get whipped up into believing made up issues. There is so much ignorance now circling this issue, in large part because of some folks sheer obsession with it.

the kind of silly mistake as originally detailed in the OP, not having enough onboard memory to function properly, is just not where the issue is going to be.

People are getting too caught up in details of what might be the ultimate cause of the issue.
It doesn't matter what the cause of the problem is.
The fine details don't matter to users and it shouldn't be up to users to solve the mystery.
DJI with all their resources and extensive experience hasn't been able to fix this one for three months.
That the GPS issue is still unresolved should be the focus for concern.

That being said ... DJI put something in their press release for the Mavic 3 that specifically referred to something different about the GPS system of the Mavic 3.
Mavic 3 comes with a powerful positioning algorithm that improves  hovering precision with signals from GPS, GLONASS, and BeiDou  satellites. This enables Mavic 3 to lock onto multiple satellite signals  faster than ever.  The increased positioning precision also makes Mavic  3 less likely to drift in the air and more stable when shooting long  exposures and timelapses.
Is the mention of a powerful positioning algorithm, just marketing spin about using Beidou sats, or does it point to DJI doing something new and different with GPS for the M3?
Is this where the problem lies?

3-29 05:23
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Labroides Posted at 3-29 05:23
the kind of silly mistake as originally detailed in the OP, not having enough onboard memory to function properly, is just not where the issue is going to be.

People are getting too caught up in details of what might be the ultimate cause of the issue.

I just came across mad tech's response to this crap in the dronexl article I am glad others with actual knowledge are speaking out. (is mad tech and mad_angler the same person?) I hate that ignorance and made up garbage is now spreading around and people are actually picking it up and making content out of it, like the original dobo video.

Unfortunately the adults cant discuss and troubleshoot the real issue because too many loud ignorant voices are dominating the airspace. This always happen. The ones with no life, the fringe characters, the ignorant, end up dominating the conversation because they have all the time in the world to sit around and stew up crap like the OP's post above. Its just a shame that content creators are now giving him the validation he is so desperate for.

@Labroides: It is possible they have dialed up the gps accuracy of the mavic 3, and this could very much so increase the acquisition time. I have spoken about this possibility in the past. In order to dial up accuracy though you potentially limit yourself to a smaller number of satellites, as some which are low on the horizon for example are kicked out and not used. It could also be that the threshold for home point lock is higher than in previous drones. In one response I saw from an engineer that was communicated to a customer through a support contact, they mentioned that the issue with the gps was in the 'algorithm' This would lend some weight to the possibility that they did try to dial up the accuracy of the gps, and in doing so have increased acquisition times a few minutes. Either way, I still say the issue is in the firmware. I will stick to that until we see evidence otherwise.
3-29 07:12
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Tornado12 Posted at 3-29 07:12
I just came across mad tech's response to this crap in the dronexl article I am glad others with actual knowledge are speaking out. (is mad tech and mad_angler the same person?) I hate that ignorance and made up garbage is now spreading around and people are actually picking it up and making content out of it, like the original dobo video.

Unfortunately the adults cant discuss and troubleshoot the real issue because too many loud ignorant voices are dominating the airspace. This always happen. The ones with no life, the fringe characters, the ignorant, end up dominating the conversation because they have all the time in the world to sit around and stew up crap like the OP's post above. Its just a shame that content creators are now giving him the validation he is so desperate for.

Here is a new article referencing mad angler's credible theory. I agree with you that he knows his stuff.

https://www.suasnews.com/2022/03/dji-mavic-3-gps-module-issue/
3-29 07:26
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Tornado12 Posted at 3-29 07:12
I just came across mad tech's response to this crap in the dronexl article I am glad others with actual knowledge are speaking out. (is mad tech and mad_angler the same person?) I hate that ignorance and made up garbage is now spreading around and people are actually picking it up and making content out of it, like the original dobo video.

Unfortunately the adults cant discuss and troubleshoot the real issue because too many loud ignorant voices are dominating the airspace. This always happen. The ones with no life, the fringe characters, the ignorant, end up dominating the conversation because they have all the time in the world to sit around and stew up crap like the OP's post above. Its just a shame that content creators are now giving him the validation he is so desperate for.

This would lend some weight to the possibility that they did try to dial up the accuracy of the gps, and in doing so have increased acquisition times a few minutes.
If that was the case, don't you think that sometime in the 3 months they've been looking for a fix, that they might have tried dialing back the "accuracy"?
In all the years that DJI's drones have been flying with GPS, has there ever been a need for more accuracy?
And as the press release was trumpeting faster GPS acquisition I doubt they would have imposed something that would have forced an unreasonable delay in sat acquisition.
3-29 08:28
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3-29 08:34
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There may be technical issues with this assessment, but the fact that some production runs with slightly different designs/parts have this issue and some do not suggests a hardware issue -- especially considering some of those changes involve GPS. That doesn't mean it ultimately can't be fixed in firmware, or at least improved, but at this point I'm doubtful all units will function 100% when all is said and done. As an aside, it's sad to see people are coming down on anyone who complains about the issue (mostly in the M3 FB forums). Just because their own units work well, they should show some patience and empathy to the ones who are still frustrated.
3-31 01:46
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there is no difference between them
4-6 01:21
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Why did the main post get deleted?
Why was the user banned?
4-6 02:10
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