ExpressLRS delivers a control link that reaches kilometers, but the telemetry return channel is just as valuable — and most pilots leave it half-configured. ELRS telemetry pushes RSSI, link quality (LQ), battery voltage, current draw, GPS coordinates, and flight mode data back to both your OSD and your radio’s display. If you’ve ever wondered why your LQ widget always reads “:100” or your radio doesn’t show any sensors, you’re missing half the ELRS value proposition. Here’s the complete integration.
ELRS Telemetry Setup Walkthrough
Step 1: Verify ELRS Firmware Telemetry Settings
ELRS 3.x telemetry ratio defaults to 1:32 on 150Hz and 1:64 on 250Hz packet rates. This means one telemetry packet is sent for every 32 or 64 control packets. At 150Hz, that’s roughly 4-5 telemetry updates per second — sufficient for voltage and RSSI, marginal for GPS coordinates at speed.
For builds that need faster telemetry (GPS rescue, long-range), flash your receiver with the FullRes option in the ELRS Configurator build flags. At 100Hz Full, you get 1:2 telemetry ratio — 50 updates per second. The tradeoff is slightly shorter range because higher telemetry power leaves the receiver transmitting more often.
Critical ELRS Lua settings to verify on your radio:
– Telem Ratio: Std (default for most use cases) or 1:2 (for GPS/fast telemetry)
– Switch Mode: 8ch or 16ch (affects how many AUX channels are available — 16ch mode reduces telemetry bandwidth)
– Link Quality: Must be enabled (default is on)
Step 2: Configure Betaflight OSD Telemetry
In Betaflight Configurator, Ports tab: the UART connected to your ELRS receiver must have “Serial RX” enabled. That’s it — ELRS uses the CRSF protocol, and CRSF carries both control AND telemetry on the same wire. No separate telemetry UART needed.
OSD tab elements to add for ELRS telemetry:
– RSSI dBm: Shows actual signal strength in negative dBm. More useful than the percentage bar. -40 dBm is excellent (transmitter next to quad), -95 dBm is fringe range. Note: RSSI dBm displays as a negative number — don’t panic.
– Link Quality: Shows 0-100 on the RF link. Below 70 is warning territory; below 50 you should turn back. LQ mode on ELRS 3.x receiver firmware defaults to hybrid mode, which combines RF link quality with SNR.
– RX SNR: Signal-to-noise ratio in dB. 6dB is minimum usable; above 15dB is excellent. SNR tells you how much your signal is above the noise floor — more useful than RSSI ppm in noisy RF environments.
– Rx Batt / VBAT: If your receiver has VBAT sensing wired, this shows flight battery voltage directly — more accurate than FC-calculated voltage because it’s measured at the receiver.
– GPS Speed / GPS Distance: Only meaningful if your ELRS receiver is running at a telemetry ratio fast enough to update these (1:2 or 1:4 recommended).
Step 3: Set Up EdgeTX Telemetry Screens
On your radio (EdgeTX 2.9+), long-press SYS → select the telemetry page for your model:
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Discover new sensors: Scroll to “Discover new sensors” and select it. Your radio scans for CRSF telemetry sensors. Wait 10-15 seconds — you should see RxBt (receiver voltage), RSSI, RQly (link quality), RSNR, and potentially VFAS (flight battery voltage from FC).
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Configure main view widgets: On the main screen, add telemetry widgets. I recommend:
– Top bar: RSSI numeric + bar
– Center: RQly (link quality as %)
– Bottom: RxBt or VFAS for voltage -
Set up voice alerts: In Special Functions, create logical switches that trigger voice alerts:
– LQ < 70: Play “Link quality warning”
– RSSI < -95 dBm: Play “Signal critical”
– RxBt < 3.5V: Play “Receiver battery low”
For radios with color screens (Radiomaster TX16S, Boxer Crush), you can also create a dedicated telemetry screen with all sensor values using the Telemetry screen widget.
ELRS Telemetry Parameter Table
| Setting | Recommended Value | Effect if Set Incorrectly | Notes |
|---|---|---|---|
| Telem Ratio (ELRS) | Std (1:32 default), 1:2 (GPS rescue) | 1:128 starves OSD updates; 1:2 on 250Hz reduces control rate | Higher ratio = more telemetry, slightly reduced range |
| Switch Mode (ELRS) | 8ch (12ms frame) for most; 16ch (25ms frame) for complex setups | 16ch halves telemetry update rate | Only use 16ch if you genuinely need all 16 channels |
| LQ Mode (ELRS 3.x) | Hybrid (default) | RF mode only misses SNR data; SNR mode alone doesn’t capture packet loss | Hybrid is the correct default for 95% of use cases |
| RSSI Channel (Betaflight) | Disabled when using CRSF | If set to AUX channel with CRSF, RSSI won’t update | CRSF provides RSSI directly — no AUX channel needed |
| Telemetry UART (Betaflight) | Same UART as Serial RX (CRSF) | Setting a separate telemetry UART wastes a port | CRSF = bidirectional on one wire |
| Display -> Units (EdgeTX) | Metric (meters, km/h, Celsius) | Imperial shows feet/mph — fine if that’s your preference | Match your region’s convention for consistency |
| Voice Alerts (EdgeTX) | LQ<70, RSSI<-95dBm, RxBt<3.5V | No alerts = you miss warnings mid-flight | Configure at minimum LQ and RSSI alerts |
Common Mistakes & How to Avoid Them
Mistake 1: Leaving Telemetry Ratio at Default for GPS Rescue Builds
The default 1:32 ratio updates GPS coordinates ~4 times per second. GPS rescue in Betaflight uses a 10Hz refresh — the 4Hz telemetry means your radio shows stale coordinates, and if you’re using the radio’s GPS display to navigate home, you’re looking at data that’s 250ms old.
Fix: Flash the receiver with a FullRes option at 100Hz or 50Hz packet rate. This gives 1:2 telemetry ratio. Accept the ~5% range reduction — you’ll have accurate GPS data.
Mistake 2: Not Discovering Sensors After Firmware Updates
ELRS firmware updates (both TX module and receiver) reset the telemetry sensor list on EdgeTX radios. Pilots update, fly, and wonder why all their widgets show zeros.
Fix: After every ELRS firmware update — TX module or receiver — go into the model’s telemetry page and run “Discover new sensors” again. Takes 15 seconds, saves a flight of troubleshooting.
Mistake 3: Confusing RSSI dBm With RSSI Percentage
CRSF telemetry sends RSSI in dBm (where -40 is strong, -95 is weak). Some OSD configurations still show an RSSI percentage bar that maps dBm to 0-100%. If you see RSSI showing “100” constantly, your OSD is using the percentage scale but reading dBm values — a -40 dBm signal registering as 40%.
Fix: In Betaflight OSD tab, use the “RSSI dBm” element instead of “RSSI Value.” dBm is the native CRSF format and is more informative — you can tell the difference between “fine” (-60) and “getting marginal” (-85).
Mistake 4: Running 250Hz Packet Rate With 16-Channel Switch Mode
At 250Hz with 16 channels enabled, the ELRS link has almost no room for telemetry. The telemetry ratio effectively drops to near-zero. Your OSD values freeze and your radio’s telemetry screen stops updating.
Fix: Drop to 8-channel switch mode if you’re on 250Hz. If you must have 16 channels, drop the packet rate to 150Hz or 100Hz to reclaim telemetry bandwidth.
⚠️ Regulatory Notice: The flight recommendations and radio operations in this article should be followed in accordance with the latest 2026 drone regulations in your country or region. Always verify local laws regarding flight altitude, no-fly zones, remote ID requirements, radio frequency licensing (2.4GHz and 900MHz), and registration before flying. Regulations vary significantly between the FAA (US), EASA (EU), CAA (UK), CAAC (China), and other authorities. ELRS operates in the 2.4GHz ISM band and 900MHz band — verify your region’s maximum allowed transmission power.
ELRS telemetry builds on the fundamentals of the ELRS protocol. If you’re still getting your receiver bound, see our ELRS binding and receiver setup guide. For the EdgeTX side of things, our EdgeTX switch mixing tutorial covers logical switches and voice alerts in detail.
ELRS receivers with full telemetry support are the heart of a reliable control link. We stock ELRS 2.4GHz and 900MHz receivers at uavmodel with diversity antennas and VBAT sensing — check the receiver collection for current options.