Telemetry

Telemetry is data sent back from the drone to your radio transmitter, giving you real-time information without looking at the OSD. It’s a second layer of awareness beyond what’s displayed on your FPV feed.

What Telemetry Provides

Data	Source	Why It Matters
Battery voltage	FC/ESC current sensor	Know when to land
Current draw	FC/ESC current sensor	Monitor power consumption
mAh consumed	FC/ESC current sensor	Most accurate “fuel gauge”
RSSI / Link Quality	Receiver	Know your radio link health
GPS coordinates	GPS module	Find your drone after a crash
GPS speed	GPS module	Speed awareness
Altitude	GPS / barometer	Height awareness
Flight mode	FC	Confirm what mode you’re in
Satellite count	GPS module	GPS reliability indicator

How Telemetry Works

CRSF (ELRS / Crossfire)

CRSF is a bidirectional protocol — the same serial link that sends stick data to the drone also sends telemetry back. Telemetry is built into the protocol with no extra wiring.

Telemetry data is interleaved with control packets. The telemetry ratio setting determines how often telemetry is sent relative to control packets:

• 1:2: One telemetry packet for every 2 control packets (fastest telemetry updates, slight control overhead)
• 1:4: Default. Good balance.
• 1:8: Less frequent updates, maximum control bandwidth
• 1:16: Minimal telemetry. Maximizes control link reliability at extreme range.

SBUS + SmartPort (FrSky)

Older FrSky systems use separate wires for control (SBUS) and telemetry (SmartPort/S.Port). Requires an additional UART connection on the FC.

Setting Up Telemetry

In Betaflight

1. Telemetry is generally enabled by default for CRSF
2. In the Configuration tab, ensure Telemetry is enabled
3. Specific sensors can be enabled/disabled in the CLI if needed

In EdgeTX

1. Go to Model > Telemetry
2. Click Discover Sensors — the radio scans for available telemetry streams
3. Sensors will appear as they’re received (Battery, RSSI, GPS, etc.)
4. Name and organize sensors as desired

Voice Alerts

EdgeTX can speak telemetry values aloud — extremely useful since you can’t look at the radio screen while wearing goggles.

Common voice alerts:

• “Battery low”: When voltage drops below a threshold
• Voltage readout on button press: Press a button, radio speaks current battery voltage
• Timer announcements: Periodic alerts (e.g., every 30 seconds) to track flight time

To configure:

1. Go to Model > Special Functions (or Global Functions)
2. Create a function: Switch = button/logical switch
3. Action = “Play Value” or “Play Sound”
4. Source = the telemetry sensor you want to announce

Telemetry Screens

EdgeTX supports custom telemetry screens on the radio’s display:

• Bar graphs for voltage
• Numeric readouts for multiple sensors
• GPS coordinates for finding a crashed drone

Configure under Model > Telemetry > Screens.

Practical Uses

Finding a Crashed Drone

If your drone crashes in tall grass or woods:

1. Note the last GPS coordinates from telemetry
2. Enter them in your phone’s maps app
3. Walk to the location
4. Combine with the drone’s beeper for audio location

This is one of the best reasons to have GPS + telemetry even on freestyle builds.

Battery Management

Voice alerts for battery voltage let you fly by feel without constantly checking the OSD:

• Set an alert at your landing voltage (e.g., 21.0V for 6S)
• Set a critical alert 1V below (e.g., 20.0V)
• Train yourself to land at the first alert

Link Quality Monitoring

LQ (Link Quality) telemetry tells you how healthy your radio link is:

• 100%: Perfect — all packets received
• 80-99%: Good — minor dropouts
• 50-80%: Warning — start heading back
• Below 50%: Critical — return immediately or expect failsafe

Telemetry Sensors Reference (CRSF)

Sensor Name	Unit	Description
RxBt	V	Receiver battery voltage (from FC)
Curr	A	Current draw
Capa	mAh	Cumulative energy consumed
GPS	lat/lon	GPS coordinates
GSpd	km/h	Ground speed
Alt	m	Altitude
Sats	count	GPS satellite count
RSSI	dBm	Signal strength
RQly	%	Link quality (ELRS)
RSNR	dB	Signal-to-noise ratio
FM	text	Flight mode string