3DR Radio Telemetry Kit 433Mhz Module Open source for APM 2.5 2.6 2.8 Type: Other Accessories Features: Very small size,light weight 433Mhz frequency band Receiver sensitivity to -117 dBm Transmit power up to 20dBm (100mW) Transparent serial link Air data rates up to 250kbps Range of approx 1 mile with supplied antennas Demonstrated range of several kilometers with a small omni antenna Can be used with a bi-directional amplifier for even more range MAVLink protocol framing and status reporting Frequency hopping spread spectrum (FHSS) Adaptive time division multiplexing (TDM) Support for LBT and AFA Configurable duty cycle Built in error correcting code (can correct up to 25% data bit errors) Open source firmware AT commands for radio configuration RT commands for remote radio configuration Adaptive flow control when used with APM Based on the HopeRF HM-TRP radio module, featuring an SiLabs Si1000 RF microcontroller.