The frsky D4R-II features:
Telemetry enabled for RSSI indication and sensor output.
1) Firmware upgradeable
2) One external analog telemetry port and one digital data-stream port (connect to FrSky Sensor Hub FSH-01)
3) RSSI (PWM) and CPPM output – If CH3 and CH4 are connected by a jumper, CH1 will output CPPM for CH1~CH8, and CH2 will output RSSI (PWM)
4) Lighter weight and physically smaller than other similar receivers.
5) Alarm warning on low voltage, poor reception, etc.