ModalAI Support,

I received a new Starling 2 Max a few days ago, and overall it's great, but I'm having a problem with GPS. Basically, the drone appears to NEVER receive any GPS signals even when left outside for long periods of time. My system info and results of px4-listener are pasted below.

This issue appears similar to these other forum discussions, where they seem to think the problem relates to EMI:

https://forum.modalai.com/topic/3879/gps-not-working-for-starling-2-max/16

https://forum.modalai.com/topic/3912/problem-acquiring-gps-satellites-possible-voxl2-board-emi?_=1731073406011

I did unplug the Lepton 8-pin JST SH connector as suggested by James Strawson in the forum discussions above, but that had no effect. I also powered down the WiFI as suggested by Alex Kushleyev, but this also had no effect, although kind of a bad test for me because I couldn't put the drone outside due to USB cable length:

• pin GPIO_157 controls VBUS, which is USB power on VOXL2
• to disable, run voxl-gpio write 157 0
• to enable, run voxl-gpio write 157 1

What do you think I should do next? Is there some way to turn the power off to various subsystems via software in an attempt to figure out if and where EMI is the problem? Any other ideas?

Thanks for your help !

Starling 2 Max Outdoor GPS-denied Development Drone × 1
with Battery Pack and Controller and Case
Dual 4k & Dual Tracking & ToF (C29)
5G WiFi and Ghost Atto 2.4GHz
ECCN: EAR99, NLR

system-image: 1.8.02-M0054-14.1a-perf
kernel: #1 SMP PREEMPT Mon Nov 11 22:47:44 UTC 2024 4.19.125
hw platform: M0054
mach.var: 1.0.1
voxl-suite: 1.4.1
current IP: wlan0: 10.0.0.19

voxl2:~$ px4-listener sensor_gps

TOPIC: sensor_gps
sensor_gps
timestamp: 841732144 (0.020669 seconds ago)
timestamp_sample: 0
time_utc_usec: 0
device_id: 11272245 (Type: 0xAC, SERIAL:6 (0x00))
lat: 0
lon: 0
alt: -17000
alt_ellipsoid: 0
s_variance_m_s: 999.00006
c_variance_rad: 3.14159
eph: 4294967.50000
epv: 3796926.25000
hdop: 99.99000
vdop: 99.99000
noise_per_ms: 64
jamming_indicator: 15
vel_m_s: 0.00000
vel_n_m_s: 0.00000
vel_e_m_s: 0.00000
vel_d_m_s: 0.00000
cog_rad: 0.00000
timestamp_time_relative: 0
heading: nan
heading_offset: 0.00000
heading_accuracy: 0.00000
rtcm_injection_rate: 0.00000
automatic_gain_control: 0
fix_type: 0
jamming_state: 0
spoofing_state: 1
vel_ned_valid: False
satellites_used: 0
selected_rtcm_instance: 0

voxl2:~$ px4-listener sensor_mag

TOPIC: sensor_mag
sensor_mag
timestamp: 861420482 (0.006257 seconds ago)
timestamp_sample: 861420007 (475 us before timestamp)
device_id: 527625 (Type: 0x08, I2C:1 (0x0D))
x: -0.04417
y: -0.32142
z: 0.42167
temperature: nan
error_count: 0
voxl2:~$

@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

@CJoseph said in Starling 2 Max no GPS data:

Hey @Alex-Kushleyev,

I'm attempting this short term fix for a project I'm working on and I'd like to keep in line with recommended practices.

Can you kindly provide the .stl file used for the 3DP mount and also inform me of the material you used to 3DP?

Thanks in advance!
Christopher Joseph.

@Alex-Kushleyev: I'm also planning to repeat your modification, and the .stl file would be very helpful to me as well. I tried a different modification yesterday but it didn't work, so copying yours is my next step.

Thanks for your help.
Bob Judd

@Alex-Kushleyev I'm hoping you or someone at ModalAI will get back to me ASAP about this because frankly I'm getting very frustrated. I added the shield below and I do get a GPS fix, but the quality is poor and when flying it is nearly impossible to avoid crashing. Why do I need to add a RF shield in the first place? Did someone at ModalAI test this $5,000 drone before shipping it to me? Does the Starling 2 Max have a GPS design issue? In view of the two similar reports below I'm beginning to think so. Please let me know how we can make this right.

https://forum.modalai.com/topic/3879/gps-not-working-for-starling-2-max/16

https://forum.modalai.com/topic/3912/problem-acquiring-gps-satellites-possible-voxl2-board-emi?_=1731073406011

@Alex-Kushleyev This morning I tried to determine if the 5G service affects the GPS signal. I removed the SIM card, turned off the power using the commands below, and verified that I had no 5G service. I also tried various combinations of these, and I also tried disabling voxl-modem and rebooting.

voxl-gpio -m 1 out
voxl-gpio -w 1 0 # power off
voxl-gpio -w 1 1 # power on

None of these had any effect on the GPS signal. It remains essentially the same as the graph I sent yesterday (20-35 db on ca. 10 satellites). This does get a GPS position lock, however, so probably I can fly.

Looking forward to your results.

@Rodrigo-Betances @Alex-Kushleyev @somalley OK I received the mast GPS fix from ModalAI and I've installed and tested it. I do get more satellites and the signal is enough to get a GPS lock, so I'm clear to fly at this point. The signal still seems a bit low but maybe that's just my location. I do have a clear view of the sky but there are tall trees not far away that may block satellites below roughly 45 degrees from the horizon.

IMPORTANT: The mast kit shipped with a ca. 10cm 6-pin cable with female JST GH connectors on each end. There is no way to connect that cable to the existing connector, and the cable itself is too short to reach the VOXL2 connector. I would suggest that one end be shipped with a male connector. Otherwise customers will need to make their own cable as I did.

Thanks for your help. Looking forward to reports from others.

@Alex-Kushleyev That's just the PETG plastic mount that I 3D printed in the picture. I'm using the GPS receiver that came with my Starling 2 Max from ModalAI (3DR taoglas).

Here's what I'm seeing in voxl-portal with my modification. ModalAI's GPS kit should arrive today, and I should be able to send you results for that in a few days.

@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

@Alex-Kushleyev @somalley

PS there is a piece of copper foil under the GPS receiver, not visible in picture.

@Alex-Kushleyev @somalley ,

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?

@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

@CJoseph said in Starling 2 Max no GPS data:

Hey @Alex-Kushleyev,

I'm attempting this short term fix for a project I'm working on and I'd like to keep in line with recommended practices.

Can you kindly provide the .stl file used for the 3DP mount and also inform me of the material you used to 3DP?

Thanks in advance!
Christopher Joseph.

@Alex-Kushleyev: I'm also planning to repeat your modification, and the .stl file would be very helpful to me as well. I tried a different modification yesterday but it didn't work, so copying yours is my next step.

Thanks for your help.
Bob Judd

@Alex-Kushleyev Circling back on this problem now, has your team identified the source of the EMI? Can I expect a long term fix that will allow me to fly my Starling 2 Max?

Thanks

@Alex-Kushleyev Thanks for the update. I had to pivot away from this project and plan to revisit it when ModalAI has a long term fix. Have your colleagues made any progress identifying the source of the EMI?

Thanks again for your help.