1. FCC vs. EU-LBT
FCC (Global Standard)
The Federal Communications Commission standard. It allows for high output power and doesn't require the radio to "check" if a frequency is clear before transmitting. This is the standard used in the US.
- + Maximum Range
- + Lower Latency (no LBT check)
- - Illegal in many European countries
EU-LBT (European Standard)
LBT stands for "Listen Before Talk." In the EU, the 2.4GHz band is crowded. Radios must listen for a fraction of a millisecond to ensure they aren't stepping on someone else's signal before they blast their data.
- + Legal in the EU/UK
- + Better behavior in crowded environments
- - Lower legal power limits (100mW)
Power Output Comparison
Toggle region to see the difference in ELRS capability.
Max Legal Power
1000mW+
Spectrum Logic
Wide open. Maximum penetration and range.
Regional Scope
Legal in USA, much of Asia, and South America.
3. How LBT Works
The "Listen Before Talk" protocol adds a tiny amount of overhead. Every time the radio wants to send a packet, it performs a Clear Channel Assessment (CCA).
⚠️ THE BINDING TRAP
An ELRS receiver flashed with FCC firmware will not bind to a transmitter flashed with EU-LBT firmware. If your radio link feels "dead" after a firmware update, check that you selected the same Regulatory Domain on both devices in the ELRS Configurator.
4. Flashing ELRS
In the ELRS Configurator, the Regulatory Domain is a mandatory selection during the build process.
# Build Options
Regulatory Domain: ISM_2400 (FCC)
Regulatory Domain: EU_868 / EU_LBT (European)
# Ensure this matches on both TX and RX!