For those who are around DJI Forum and other places you may have seen a post regarding the GPS Issues with the Mavic 3, this post makes reference to DJI using a different GPS module in the Mavic 3 than other models. Specifically the KT and KA variants of the UBX-M8030 GNSS Chipset.
The UBX-M8030KT is the professional-grade chipset and the UBX-M8030KA is automotive grade.
All the M8030 models have the same internal basic layout of CPU and SRAM including the amount, the difference 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 labelled as automotive-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 noting 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 frequency of them we are seeing.
The fact there is a battery backup is a very good sign 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 has 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.
Furthermore, DJI would not use GPS memory onboard 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 something going on for sine users . 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 .
A final note on another change with the Mavic 3, DJI switched from 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 a 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. Right now if you’re 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 has released firmware to address it shows is a far more complex issue than just a simple bug, perhaps it’s going to just be the way it is the new system, but they are clearly trying but software and if it is hardware-software can’t fix bad hardware and if it is an issue with yours 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. However to put this all to bead I have ordered a Mavic 3 GPS module.
We will tear this down on the bench and do some testing to see what’s really going on More on this to come next week. Stay safe Mad.