Your goggles show you OSD data. Your radio screen can show you everything else — and it does it without cluttering your video feed. ELRS telemetry sends battery voltage, link quality, GPS position, and flight mode back to your transmitter at up to 250Hz. With the right Lua script, you get a second dashboard that works even when your goggles are off or your video feed drops. I started using radio-side telemetry during long-range flights and now I won’t fly without it.
ELRS Telemetry: What Gets Sent and at What Rate
ExpressLRS sends telemetry in the same packet stream as RC commands. The telemetry ratio is configurable — it determines how many telemetry packets are sent per RC packet cycle.
At the default 1:128 ratio on 500Hz packet rate, you get roughly 4 telemetry updates per second. That’s fine for battery voltage and GPS coordinates, which change slowly. For RSSI and link quality — where you want sub-second response to signal drops — switch to a 1:32 or 1:16 ratio. The tradeoff is slightly higher CPU load on the receiver and reduced maximum range, but on any modern ELRS receiver the difference is negligible below 1:8.
Key Telemetry Sensors
The ELRS Lua script exposes these sensors to EdgeTX:
– RxBt: Receiver battery voltage (on the quad side — shows pack voltage if Rx is VBAT-powered)
– RSSI: Signal strength in dBm (negative values; above -50 is excellent, below -100 is critical)
– LQ: Link quality as a percentage (0-100). Below 80%: you’re pushing range. Below 50%: turn back now.
– GPS: Latitude, longitude, altitude, ground speed (requires a GPS module connected to the FC receiving ELRS telemetry via MSP)
– FM: Flight mode from Betaflight (useful for confirming GPS Rescue activated)
EdgeTX Lua Script Setup
Step 1: Flash the ELRS Lua Script
The ELRS Lua script is not pre-installed on most EdgeTX radios. Download elrsV2.lua from the ExpressLRS Configurator’s releases page and copy it to the SD card’s /SCRIPTS/TOOLS/ directory. On a Boxer or TX16S, the path is /SCRIPTS/TOOLS/elrsV2.lua.
To verify it’s installed: press the SYS button, navigate to the Tools page, and confirm “ExpressLRS” appears in the list. If it doesn’t, the script is in the wrong directory or the filename doesn’t match what EdgeTX expects.
Step 2: Configure Telemetry Widgets
EdgeTX supports telemetry widgets on the main screen. On a TX16S color screen, you can display 4 widgets simultaneously. The most useful configuration I’ve found:
- Top-left: RxBt (pack voltage) — large font, always visible
- Top-right: RSSI (dBm) — with color thresholds (green > -80, yellow -80 to -95, red < -95)
- Bottom-left: LQ (%) — same color thresholds
- Bottom-right: GPS altitude or distance from home
Set the widget update rate to match your telemetry ratio. If you’re running 1:32, the widgets can update 15 times per second — no need for screen refreshes faster than that.
Step 3: Audio Callouts for Critical Thresholds
This is the feature that changes how you fly long range. In EdgeTX’s Special Functions menu, configure audio callouts triggered by telemetry values:
- When LQ drops below 80%: play “Link quality warning” (one-time, repeat every 10 seconds)
- When RxBt drops below 3.5V per cell: play “Battery low” with the actual voltage value
- When RSSI drops below -100dBm: play “Signal critical” and vibrate
These callouts work even when you’re looking at your video feed. You hear the warning before you see the OSD flash — and in a long-range flight, a 2-second earlier warning from your radio can be the difference between turning back with margin and losing the link.
Parameter Comparison Table
| Telemetry Sensor | Update Rate at 1:128 | Update Rate at 1:32 | Best Display Method | Critical Threshold |
|---|---|---|---|---|
| RxBt (voltage) | ~4 Hz | ~15 Hz | Widget (large) + callout | 3.5V/cell |
| RSSI (dBm) | ~4 Hz | ~15 Hz | Widget + callout | -100 dBm |
| LQ (%) | ~4 Hz | ~15 Hz | Widget | Below 80% |
| GPS Lat/Lon | ~4 Hz | ~15 Hz | Widget (small) | N/A |
| GPS Altitude | ~4 Hz | ~15 Hz | Widget (small) | N/A |
| Flight Mode | ~4 Hz | ~15 Hz | Widget (small) | GPS Rescue active? |
Common Mistakes & What Most Pilots Get Wrong
Mistake 1: Assuming LQ and RSSI Are the Same
RSSI measures raw signal strength. LQ measures the percentage of successfully received packets. You can have RSSI at -60dBm (strong signal) and LQ at 20% (massive packet loss) if there’s interference from another pilot’s VTX blasting on a nearby frequency. RSSI tells you how loud the signal is. LQ tells you whether your receiver can actually decode it. Always trust LQ over RSSI for go/no-go decisions.
Mistake 2: Running Full Telemetry Ratio on a Race Build
A 1:16 telemetry ratio on 500Hz packet rate means roughly 31 telemetry packets per second. On a race quad where every millisecond of link latency matters, those telemetry packets compete with RC data packets for airtime. Drop the telemetry ratio to 1:128 or disable telemetry entirely (-DENABLE_TELEMETRY=false in the receiver firmware) for racing. You don’t need battery voltage on your radio when the quad is 50 meters away on a track.
Mistake 3: Configuring Audio Callouts Without Hysteresis
EdgeTX plays an audio callout every time a telemetry value crosses a threshold. If your RSSI is bouncing between -98 and -102 dBm, you get “Signal critical” every time it dips below -100 — which could be 3-4 times per second during a flight. Set hysteresis in the logical switch: trigger at -100, clear at -94. The 6dB gap prevents chatter. Without it, your radio screams at you for the entire return leg.
⚠️ Regulatory Notice: The flight recommendations 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, and registration before flying. Regulations vary significantly between the FAA (US), EASA (EU), CAA (UK), CAAC (China), and other authorities. ELRS output power above 100mW may require an amateur radio license in certain jurisdictions — check your local requirements before enabling dynamic power or high-power modes.
Internal Links
ELRS telemetry only works if your receiver is properly bound — our ExpressLRS binding methods guide covers the three binding methods and how to verify the connection before you rely on telemetry data inflight.
For GPS-dependent telemetry, you need a solid GPS lock with reliable rescue configured — our Betaflight GPS Rescue setup guide walks through the complete configuration so your telemetry data is backed by a working return-to-home system.
Joshua Bardwell’s EdgeTX telemetry setup video is the best walkthrough for widget placement and audio callout configuration — he covers the hysteresis trick and per-model telemetry screen setups.
The Radiomaster Boxer ELRS with its built-in 1W transmitter and large monochrome screen is the ideal radio for telemetry-heavy flying — uavmodel.com stocks the Boxer with AG01 gimbals and pre-configured EdgeTX so your telemetry widgets are ready to go out of the box.