Starling 2 - RC link dropout debug assistance
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Note that this query is somewhat related to another post I just made on the forum, but I wanted to query more generally about the issue we're seeing without direct reference to the context in my other post which is specifically related to power margin.
Hello. My client is experiencing issues with RC link dropouts. The system description is below, followed by the description of the failure modes.
The platform is a customized Starling 2 / VOXL 2 (QRB5165, Ubuntu 18.04), SKU roughly MRB-D0016(?)-4-V?-C29-T7-M0-X? — I don't have the unit on hand at the time of writing, so the family and hw-version fields are unconfirmed. Some more system details are below.
Power: The drone runs on a 4S battery. The VOXL 2 receives its power via the VOXL mini ESC power module 5V output.
Cameras: The C29 M0173 front end. There's also a VL53L1X on the M0173 front end that's part of the C29 config, though not with a Lepton as shown in the front-end documentation, but as a single "rangefinder" as described in the rangefinder documentation.
Custom expansion: A custom hat board carries a connector that interfaces your MCBL-00022 harness and an AWUS036EACS USB Wi-Fi dongle. The hat also has connectors which interface four VL53L8CX ToF sensors modules (also your design, i don't have the PN for them) behind an I2C switch (the one you recommend). That is the extent of the expansion.
Failure Mode #1 (FM1) Loss of RC network bars on transmitter display. The RC transmitter stops showing link/network bars, suggesting the ELRS link has dropped.
- Occurs randomly
- Has been observed both at close range and at moderate line-of-sight distances
- Tends to occur around RC power cycling events
- Recovery requires multiple RC power cycles and is not guaranteed
- Not reproducible on demand
Failure Mode #2 (FM2) RC shows paired/connected but drone does not respond to input.
- Transmitter displays network bars indicating a connected ELRS link while the flight computer does not respond to RC input
- Suggests the RF link itself remains intact
- Recovers inconsistently after power cycling
Generally speaking, what is the recommended procedure to debug this issue? Thanks.
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Hey, If you're able to update the SDK and run voxl-elrs update it may have some bug fixes to improve reliability.
I would also check that the receiver antenna is still connected and is not damaged as that can significantly reduce the range.
If the transmitter is showing signal but the drone is not responding it's possible you are bound to another transmitter.
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here's the hardware details which i guessed at originally...
voxl2:~$ voxl-inspect-sku family code: MRB-D0012 (starling-2-max (D0012)) compute board: 4 (voxl2) hw version: 2 cam config: 29 modem config: 28 (M0151 w/ Alfa Networks WiFi Dongle AWUS036EACS) tx config: 7 (elrs_beta_fpv) extras config: 0 (none) SKU: MRB-D0012-4-V2-C29-T7-M28-X0 voxl2:~$ voxl-version ──────────────────────────────────────────────────────────────────────────────── system-image: 1.8.04-M0054-14.1a-perf kernel: #1 SMP PREEMPT Mon Mar 24 22:31:58 UTC 2025 4.19.125 ──────────────────────────────────────────────────────────────────────────────── hw platform: M0054 mach.var: 1.0.1 SKU: MRB-D0012-4-V2-C29-T7-M28-X0 ──────────────────────────────────────────────────────────────────────────────── voxl-suite: 1.5.0 ──────────────────────────────────────────────────────────────────────────────── Packages: Repo: http://voxl-packages.modalai.com/ ./dists/qrb5165/sdk-1.5/binary-arm64/ Last Updated: 2026-01-20 16:49:08 List: libfc-sensor 1.0.7 libmodal-cv 0.5.18 libmodal-exposure 0.1.4 libmodal-journal 0.2.6 libmodal-json 0.4.7 libmodal-pipe 2.13.2 libqrb5165-io 0.5.0 libvoxl-cci-direct 0.3.3 libvoxl-cutils 0.1.5 modalai-slpi 1.2.0 mv-voxl 0.1-r0 qrb5165-bind 0.1-r0 qrb5165-dfs-server 0.2.0 qrb5165-imu-server 1.1.3 qrb5165-mini-tof-server 0.2.2 qrb5165-rangefinder-server 0.1.5 qrb5165-slpi-test-sig 01-r0 qrb5165-system-tweaks 0.3.6 qrb5165-tflite 2.8.0-2 voxl-bind-spektrum 0.1.1 voxl-camera-calibration 0.6.0 voxl-camera-server 2.2.4 voxl-ceres-solver 2:1.14.0-10 voxl-configurator 1.0.2 voxl-cpu-monitor 0.6.0 voxl-docker-support 1.3.1 voxl-elrs 0.4.7 voxl-esc 1.5.4 voxl-feature-tracker 0.5.2 voxl-flow-server 0.3.6 voxl-gphoto2-server 0.0.10 voxl-joystick-server 0.0.6 voxl-jpeg-turbo 2.1.3-7 voxl-lepton-server 1.3.3 voxl-lepton-tracker 0.0.4 voxl-libgphoto2 0.0.4 voxl-libuvc 1.0.7 voxl-logger 0.5.3 voxl-mavcam-manager 0.6.0 voxl-mavlink 0.1.5 voxl-mavlink-server 1.4.9 voxl-modem 1.1.8 voxl-mongoose 7.7.0-2 voxl-mpa-to-ros 0.3.9 voxl-mpa-tools 1.4.0 voxl-open-vins 0.4.19 voxl-open-vins-server 0.3.12 voxl-opencv 4.5.5-3 voxl-osd 0.1.8 voxl-portal 0.7.11 voxl-px4 1.14.0-2.0.105 voxl-px4-params 0.7.5 voxl-qvio-server 1.2.0 voxl-remote-id 0.0.9 voxl-reset-slpi 0.0.1 voxl-state-estimator 0.0.5 voxl-streamer 0.7.5 voxl-suite 1.5.0 voxl-tag-detector 0.0.5 voxl-tflite-server 0.4.1 voxl-utils 1.4.8 voxl-uvc-server 0.1.7 voxl-vision-hub 1.8.23 voxl-vtx 1.4.7 voxl-wavemux 0.0.1 voxl2-io 0.0.3 voxl2-system-image 1.8.04-r0 voxl2-wlan 1.0-r0 ──────────────────────────────────────────────────────────────────────────────── voxl2:~$ voxl-inspect-services Scanning services... Service Name | Enabled | Running | CPU Usage ─────────────────────────────────────────────────────────────────── docker-autorun | Disabled | Not Running | <redacted>-voxl-docker | Enabled | Running | <redacted>-voxl-sync | Enabled | Completed | <redacted>-voxl-tmux | Enabled | Completed | modallink-relink | Disabled | Not Running | 39.2% voxl-camera-server | Enabled | Running | 0.0% voxl-cpu-monitor | Enabled | Running | voxl-dfs-server | Disabled | Not Running | voxl-elrs-startup | Disabled | Not Running | voxl-feature-tracker | Disabled | Not Running | voxl-flow-server | Disabled | Not Running | 0.0% voxl-imu-server | Enabled | Running | voxl-joystick-server | Disabled | Not Running | voxl-lepton-server | Disabled | Not Running | voxl-lepton-tracker | Disabled | Not Running | voxl-logger | Disabled | Not Running | 0.0% voxl-mavcam-manager | Enabled | Running | 3.9% voxl-mavlink-server | Enabled | Running | 7.8% voxl-mini-tof-server | Enabled | Running | voxl-modem-doodle | Disabled | Not Running | voxl-modem | Disabled | Not Running | voxl-open-vins-server | Disabled | Not Running | voxl-osd | Disabled | Not Running | 2.0% voxl-portal | Enabled | Running | 21.6% voxl-px4 | Enabled | Running | 21.6% voxl-qvio-server | Enabled | Running | 2.0% voxl-rangefinder-server | Enabled | Running | voxl-remote-id | Disabled | Not Running | voxl-seek-server | Disabled | Not Running | voxl-softap | Disabled | Not Running | voxl-state-estimator | Disabled | Not Running | voxl-static-ip | Disabled | Not Running | 0.0% voxl-streamer | Enabled | Running | voxl-tag-detector | Disabled | Not Running | voxl-tflite-server | Disabled | Not Running | voxl-time-sync | Disabled | Not Running | voxl-uvc-server | Disabled | Not Running | 7.8% voxl-vision-hub | Enabled | Running | voxl-vrx | Disabled | Not Running | voxl-vtx | Disabled | Not Running | voxl-wait-for-fs | Enabled | Completed | voxl2:~$ -
Hey, If you're able to update the SDK and run voxl-elrs update it may have some bug fixes to improve reliability.
I would also check that the receiver antenna is still connected and is not damaged as that can significantly reduce the range.
If the transmitter is showing signal but the drone is not responding it's possible you are bound to another transmitter.
@Ben-Linne I'm likely able to perform those updates. A fix is good, but root cause understanding of the issue is better at this point, so I will try updates once all other debug opportunities are spent if I can't reach a deterministic resolution.
receiver antenna [...]
understood and checked out. I've confirmed the umcc(u.fl) connection is fully seated and no damage is present anywhere.
If the transmitter is showing signal but the drone is not responding it's possible you are bound to another transmitter.
this is a state I will confirm. So far though, I believe the failure mode is observable with no other transmitters powered, but i will confirm.
Thanks.
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