Then I will talk about some frsky receivers from the series d I hope it helps you as it serves me   in this hobby 

1st D8R-XP

                       

The D8R-XP is a special receiver that is identical to the D8R-II Plus, but was to added the RSSI and CPPM outputs commonly used for aircraft FPV.CPPM can reduce wiring some drivers flight a single servo extension can be all 8 channels to the flight computer. Additionally the CPPM output can be used as a wireless trainer system (wireless trainer cable). The RSSI output is used with on-screen display (OSD) systems that are common in first person view ( FPV) vehicles . (All Frsky telemetry receivers they send RSSI levels back to the transmitter, but this receiver can generate this data for use with an OSD).

Among its main functions they have the following points:

  • Two external analog telemetry ports (A1 & A2) are connected by a digital data stream ( Rx ) port
  • 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)
  • When the side port pins of A1 and X are connected by jumper A1 it will change from the external analog telemetry port to the internal built-in battery voltage sensor.
  • Upgradeable firmware
  • Low voltage alarm warning, bad reception, etc ... 

Among its specifications are

  • Dimension 55 * 25 * 14mm. Its weight is 12.4g. Its operating range is full range ( > 1.5km) .Its operating voltage range is 3.5 to 10V. Its operating current is 100mA. Number of channels it has of 8ch.

2nd D8R-II plus

                     

D8R-II supports PPM signal. It is an upgrade from the previous D8R-II providing a now added internal voltage sensor, as well as the use of an external voltage sensor, The internal voltage sensor provides packet monitoring for glider pilots and IC +. An external sensor facilitates the provision of flyers EP.

 

Among its main functions they have the following points:

  • Two analog telemetry ports (A1 & A2) and one digital data stream port ( Rx )
  • When the side port pins of A1 and X are connected by the jumper, A1 will switch from external analog telemetry port to internal built-in battery voltage sensor
  • Convenient Upgrade - No need to open the receiver box when upgrading D8R-II anymore
  • Low voltage alarm, bad reception, etc.

Among its specifications are

  • Dimension 55 * 25 * 14mm. Its weight is 12.4g. Its operating range is full range ( > 1.5km ) .Its operating voltage range is 3.5 to 10V. Its operating current is 100mA. Number of channels it has of 8ch.

3rd D4R.II

                    

At a glance this D4R-II is a full size mini 4 channel receiver by frsky. What makes this receiver different from the D4FR? The D4R-II's data port allows you to connect a sensor hub so you can connect GPS, variometer , temperature , RPM, and all the big frsky sensors . It also has 2 detachable full-length antennas. All this is available in one package a little more bigger than the D4FR.

Among its main functions they have the following points:

  • Upgradeable firmware
  • One external analog telemetry port and one digital data stream port ( connect to frsky sensor Hub FSH-01
  • 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)
  • Weight more lighter and physically more small
  • Alarm warning low voltage, poor reception, etc ..
  • Among its specifications are

 

Among its specifications are

  • Its dimension is 40 * 22.5 * 6mm. Its weight is 5.8g / 5g ( naked). Its operating range is full range  ( > 1.5km), Its operating voltage range is 3.5 to 10V. Its operating current is 60mA. Number of channels is 4ch.

4th TFR4

                          

TFR4 supports CPPM and RSSI (PWM) output: if CH3 and CH4 are jumpered, CH1 will output CPPM for CH1-CH8 and CH2 will output RSSI (PWM).
TFR4 has two selectable failsafe configuration options.

Among its main functions they have the following points:

  • CPPM and RSSI (PWM) output - If CH3 and CH4 are jumpered, CH1 will output CPPM for CH1-CH8, and CH2 will output RSSI (PWM ) Lighter weight and physically smaller  
  • Two selectable failsafe configuration options (use native failsafe on radio side or set failsafe on TFR4 side)

Among its specifications are

  • Your Compatibility Air systems (7CH mode / multiple mode) 6EX, 7C, TM-7, TM-8, T8FG, T10C, TM-10, T10CG, T12Z, T12FG, TM-14, T14MZ, etc.

              Surface systems (C1 mode) 3PK, 4PK, etc

  • Its dimension 34 * 19 * 8mm
  • Operating voltage range is 3.5 to 10V
  • Number of 4ch channels
  • Operating temperature range -10oC to 80 oC