Poor GPS Fix
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https://forum.modalai.com/topic/4226/starling-2-max-no-gps-data
Just found this discussion and is likely the cause for my problems considering the two satellites I did track were right above me and still had very low SNR levels (20's). This seems like a pretty bad design flaw that should have been caught in testing. I'm going to try some testing and experimentation on my end to try and mitigate the EMI and will report back with any results that appear promising.
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Building upon what @ROBERT-JUDD did in his testing, we made a shield out of a tinfoil solder cup to isolate the GPS antenna from the rest of the drone. This resulted in an almost immediate track of 10+ satellites. The EMI problem is real. We are now working on designing a 3D printable cone similar to what the cup is doing that we plan to paint with an EMI coating that will be our more rugged long term solution.
ModalAi should be providing clear disclaimers about this problem before people go and spend thousands on this drone!
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@somalley @Alex-Kushleyev Thanks for referring to my March 1, 2025 post regarding the GPS problem:
https://forum.modalai.com/topic/4226/starling-2-max-no-gps-data
Overall I'm a big fan of ModalAI, but in my opinion this product contains a fundamental design flaw (complete loss of GPS position data due to EMI) that should have been detected and corrected early in the design testing phase. Moreover, that fatal design flaw has remained uncorrected for many months now, and I have received no information about if/when a permanent fix will be available. Our company spent over $5,000 on a Starling 2 Max, and it remains largely unusable due to this problem.
Alex Kushleyev at ModalAI has in general been very responsive, and has developed a temporary fix that customers can implement on their own, which I genuinely appreciate. But the fact remains that ModalAI inexcusably sold a product with a fundamental design flaw, and has not offered a permanent fix for many months now. In my opinion, at this point a permanent fix should be one of ModalAI's highest priority if they want to avoid a significant loss of customer confidence.
I would suggest that, as a first step, ModalAI should create a new post dedicated to providing ongoing fix updates and timelines, and to systematically update that post on the same day and time each week until a permanent fix is made available.
Thank you for your consideration.
Robert Judd
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Hello @ROBERT-JUDD and @somalley ,
Thank you for following up and I appreciate your feedback. I have relayed your comments (again) to the team and will push to get the workaround out.
For Starling 2 Max, the workaround is to install a mast, so we are working on making those details available. Shielding the GPS receiver in the default location is not as effective. Please refer to the testing done with a mast in the center of the drone in this thread : https://forum.modalai.com/topic/4226/starling-2-max-no-gps-data/38 . However, the workaround is probably going to have the mast in the back of the Starling 2 Max.
For Starling 2, @somalley , a similar solution should be possible (with a mast). We are targeting the fix for the Starling 2 Max first, however you may be able to use the same approach (elevate the GPS receiver as well as getting it farther from the usb wifi dongle, which is right under the gps receiver, and seems to cause interference sometimes on Starling 2). We have seen improvement on Starling 2 when the wifi dongle is mounted elsewhere, but also elevating the GPS receiver should help as well as putting a small shield at the bottom.
voxl-portal now supports displaying the GPS SNR, so it should be easier to validate the signal improvements based on SNR directly (as opposed to time to lock, etc).
Again, sorry for the inconvenience and I will check in a few days regarding the status of the workaround.
Alex
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Alex: Thanks for the reply. I tried to duplicate your workaround, see picture. The GPS signal did improve to the point where I could see 9-10 satellites, but I could not get a position lock and still could not fly.
Question: in the picture from your post (see below), what is the object that I've circled in blue? Is that something that might explain why your GPS signals are much better than mine?
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PS there is a piece of copper foil under the GPS receiver, not visible in picture.
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Our team is getting together a GPS mast kit we can send out for testing on Starling 2 Max. I believe your name is already on the list to receive it.
Regarding your question, the item you circled in blue is a 6-pin connector board that allowed me to extend the short cable using another 6-pin cable. It is kind of bulky, so i just taped over it.
In your implementation, does that look like you have two antennas stacked on top of each other? Can you please elaborate?
Also, did you get a chance to try out the GPS signal viewer in the
voxl-portal? how high were your SNR during your test in open sky?Additionally, as i mentioned before, the proximity of RC transmitter (within < 2 meters) of the drone seems to decrease SNR, so please check that. It seems the RC transmitter is sending out signal outside of 900mhz band, which affects GPS.
Regarding the upgrade mast kit, i am also going to receive it and test it to confirm that it performs similarly to my initial mast.
I am going to perform some more testing in the next few days. I know there are a lot of factors that can affect the GPS signal, i will try to summarize them all in a shorter write-up.
Alex
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@Alex-Kushleyev Thanks for the info. Yes your team has shipped a GPS mast kit to me and it should arrive tomorrow. Thanks very much for making that happen. I'll try it and let you know the results in the next few days.
In my implementation I did not have two antennas, only one. I did try the GPS viewer in voxl-portal and it worked great, much more convenient than Ublox Ucenter. The GPS signals I received were about 20-30dB in open sky with up to 9 satellites. Much better than before but not enough to get a lock. I did not power up the RC transmitter because I'm connecting exclusively with 5G Google Fi when the drone is outside (inside I use the USB cable). I've also removed the WiFI USB device just to limit the possibilities.
Looking forward to testing the mast kit.
Bob
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@ROBERT-JUDD , 20-30dB is still very low, so something else is going on. Ideally, majority of satellites in open sky would be above or around 40dB. If it is at all possible, can you try disabling the 5G modem and instead just use USB connection with adb forwarding to look at
voxl-portal: https://docs.modalai.com/voxl-portal-via-adb/The reason why i asked about two antennas is because it looks like you have two antenna stacked on top of each other in your picture. Or is it just a plastic mount?
. Maybe i am just not familiar with this GPS receiver you are using.I should be getting my kit later today, so i will test it out. In my early tests i was using the original GPS module that came with Starling 2 Max and it was fine ( you can see it in the screen shots that you also shared in this thread).
Alex
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@Alex-Kushleyev said in Poor GPS Fix:
I believe your name is already on the list to receive it.
Anyway we can get on that list too? We received our starling 2 max nearly a month ago now and have only recently been able to test it. We're happy with everything but the GPS problem makes this product borderline unacceptable. We just had a meeting where we decided to hold off on ordering 5 more starlings because of this issue!
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@Rodrigo-Betances , yes, absolutely. I will provide your name to the team.
