# Glossary

## Technical words with explanations¶

Below you can find a list of terms you might not be sure about, as well as some common abbreviations:

• BL: Bootloader, loads the FW
• CRSF: TBS Crossfire, more specifialy in our case most often refering to the communication protocol between TX and TX module and RX and FC respectively
• ESC: Electronic Speed Controller
• FC: Flight Controller
• FW: Firmware
• LQ: Link Quality, percentage of expected packets received. Our preferred method of measuring the quality of the control link
• Lua: Means "Moon" in Portuguese. As such, Lua is the correct way to write and not all uppercase. The ExpressLRS Lua script can be installed on a OpenTX radio, to easily alter TX parameters like Packet rate, Telemetry ratio and Output power. But also shows if the radio (OpenTX) is communicating correctly with the module. ( e.g. 0:50, 0:150, 0:200 and so on.)
• MCU: Micro Controller Unit, generally denotes an embedded system controller as opposed to big iron cpu
• OSD: On Screen Display, refer to this page for instructions for setup in BF
• OTA: Update your device Over The Air (wifi)
• OTX: OpenTX
• RSSI: Received Signal Strength Indicator, "arbitrary" scaled version of RSSI dBm or LQ. Signal Health: LQI and RSSI Explained
• RSSI dBm: Measure of power level measured in dBm. Basically, how strong the signal being received is
• S.Port: SmartPort, sometimes referred to as sport. FrSky "telemetry" protocol. The S.Port also gets used for updating FrSky receivers.

To be continued.