Few days ago I've mentioned in other thread about new project of alternative transmission.

Now - more details.

Phase 1:

Universal RC/data transmission module - 434/868 MHz, 500 mW (27dBm) regulated power.


- RF-SMA for antenna,

- PPM in and out

- 9 channels - servo type as in standard RC Rx,

- serial interface - hardware and software compatible with 3DRadio,

- miniUSB - parallel to serial.

Software, after power-on, is "listening" on PPM-in port - if there is correctPPM signal - then "ground module" procedures are activated, if no - "air module". 

Configuration - via Mission Planned / 3DRadio config software / dedicated PC/Mac/IOS/Android applications.

RF power regulation - 3-position switch (micro=range check/binding, std=100mW, hi=500mW

RF Module - Dorji DRF4432F27

CPU - STM32F103CBT6.

Phase 2:

500 mW, 5.8 GHz video tx with additional functions:

- 3 switchable video inputs: 2 - composite video and 1 HDMI. Switching by standard RC servo-type interface,

- photo camera trigger - IR/relay/OC transistor

RF Module - Airwave


Phase 3: Integration.

Products from phases 1 and 2 with some more on single boards:

"Ground" - functions from module phase 1 and: interface for potentiometers and switches/buttons for build stand alone (without RC tx) solution; drivers for antenna tracker - 2 servos/2stepper motors with "polulu protocol" for Mission Planner compatibility, GPS/IMU for antenna position (for moving ground stations), 5.8 GHz diversity receiver, MinimOSD compatible OSD with outputs: "pure video" / video+OSD / OSD only.

"Air" - functions from modules phase 1 and 1 and: output for servo for pan tracking for video tx antenna, GPS module for GPS+Glonass satelites, power measurement (current/voltage) used by video and data transmission, GSM/GPRS for SMS message with lat/lon sending in case of system failure, lost control, etc.


Phase 1 - PCB design almost finished, All parts on the table, Monday will sent it to production - 2 weeks and 5 sets for beta tests will be ready <- betatesters welcome...

Phase 2 - next month - now waiting for HDMI-to-composite IC's for finishing design.

Phase 3 - few units for beta tests - January 214.

All comments, ideas - welcome.

to be continued/updated...

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Schematic drawing for module phase-1 almost ready...

Comments welcome!

Hardware possibilities:

- transparent serial channel. P15-serial and P16-USB as interfaces.

- up to 12 PWM servo-type channels (50/100/200/400 Hz - software selection)

- servo channel 12 - configurable: servo or RSSI output (software+CB2)

- transparent PWM channel - P13 - PPMin/out

- RF power - via 3 position switch connected to P18 or via servo channel - configurable by software setup

- DC power - can be delivered from servo rail or separate servo and electronics (via serial interface) (CB1)

- JTAG interface (P19)  and boot selectors (P17) - only for prototyping/test modules.

- binding - via bind button (S2) and/or software (possible one-to-many, one-to-one, many-to-many RX/TX)

- PPM output can work concurent with servo channels.


Schematic drawing for phase - finished.
This is single module - for both ground and air use.
After discussion with potential users and some research - here are basic hardware features:

1. RF module 500 mW - 434 or 868 MHz version, RP-SMA socket for antenna, can be soldered horizontally or vertically

2. 3-pin goldpin connectors (also vertical or horizontal mounted) :

  • 1 pc - PPM in/out - input or output of PPM signal. Input - ground module, output air module - for autopilot connection
  • 9 pcs - Servo - 9 channels for servo contol, same as normal RC receiver (for ground version - optional connection for 9 inputs from ground station, 5 of its can be defined as analog - from potentiometers (gimbals), all as digital - from buttons switches. Additional software defind option is to connect headtracker signals (PPM or PWM) and mix its with RC channels => PPM expander),
  • 2 pcs - Servo - two channels for antenna tracker (pan/tilt) in ground module and channels 10 and 11 in air module
  • 1 pc - RSSI/LQ (GND, RSSI, LQ) - analog output (from DAC IC's) for RSSI and quality L/Q. Min-max standard selectable by on-board switch 0-3.3 or 0-5V.
  • 1 pc - connector for 3-position switch for RF power selection (micro, low, high). RF power can be also regulated via one of standard RC channel (1 to 11) - selection by software contigurator and/or by MAVLink/extended AT commands.

3. Other connectors:

  • 1 pc USB mini typ A - fot data transmission and configuration
  • 1 pc goldpin 6-pin - serial port for data transmission
  • 1 pc 2x10 pin - JTAG for program/debug - only in test/prototype modules
  • 1 pc 4-pin interface I2C for future I2C external modules (IMU, GPS, voltage, current, etc)

4. Module is also equipped with:

  • 2 LED (green and red) for status display (that is for test version. In final version - probably one will be enough, and second will be replaced by transistor/relay/IR diode for camrea trigger, etc.
  • 2 buttons - reset and bind.
  • 1 buzzer frequency controlled - as a status, lost packets, vario, model finder, etc.
  • 1 circuit breaker for RSSI/LQ voltage level selection
  • 1 circuit breaker for boot type selection - only for test modules.

General - in design was used all pins of STM32F103 IC. This module will be an universtal start-up for software development. Both internal soft, and external - configurator, state display, etc - for PC/MAC/IOS/Andriod/etc

I will make 3-5 sets of such modules for beta-testers and those who wish to cooperate with software development. Everyone is interesting - please PM/e-mail me.

Hi Marek,

What is the development status of your modules? Is Phase 1 already tested and commercially delivered ?

Is any price estimate yet?

Too much features for me to betatest easily ;-)

Hi Marek,

what is the status of this project?

I think there are still many people waiting for something just like that!

This sounds too good to be true :P In fact it sounds very much like what we would call a "egg laying wool milk sow" XD

Well I hope that you aren't going megalomaniac.. but I sure hope that you succeed building it! It would be the perfect solution for the problem I'm facing now.. even though I'd prefer 2.4Ghz VTX :D

Keep us updated!

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