Iridium communication and PX4 in an airship

Hi, am considering using a PX4 and an Iridium satellite unit to operate my airship. I have read trough the instructions on the PX4 user guide, but would like to hear if anyone have tested it out in actual operations, and give me a first idea of how easy or difficult it would be to integrate into an airship operation, based on their experience.


Sorry for the late response.
We have used the module and satellite communication for several flights with our airplanes. I think I improved the integration from the software side quite a bit but you still might have issues. Depending on the hardware you are using the wiring is not trivial as you need a high power serial port or an external power source to power the module.

If you have any issue in setting up the satcom system just let me know and I check how I can support you.

Hi Florian
Fantastic! My project has just wasted one and half year, and to me, substantial funds on a proprietary autopilot solution. We just decided that enough is enough and set out to find an alternative.
I think we realized that the chance of getting a response was slim, so we are grateful to have your response.

When I say “we”, I refer to myself and my partner/tech. support Mr. Bradley Nel at Industratech. I am located I Bergen Norway and he is based in Durban South Africa. I started the project five years ago purely as a one man operation on my spare time, and Bradley joined in, three years back. I have set up a webpage to keep interested parties informed. You find it here: Solairship.

Mr. Nel just received the PX4 last week and is looking into the configuration. I will invite him in now that we have made contact, and he will have questions I am sure.

Pretty cool to hear about your project. It is definitely a challenge from the hardware and software side but based on the experience from our lab I think the biggest issue might be getting the approval to execute the flight. The goal of one our projects (AtlantikSolar) was also to cross the Atlantik from Portugal to Canada. However, eventually we abandoned it because getting the permission to fly would require to much paperwork and would also cost too much.

Hi acfloria

Well nice to meet you! I have received the PX4 and been attempting to set the unit up and learn about the interfaces and all its functionalities. Having a few issues to start. I wonder if you could assist in any way.

I was thinking of leaving the irridium module till last and just get all the other bits and pieces working as per normal. I have managed to do the following:

  • Link to PC upgrade firmware in QGC. (developer master)
  • Link to Ardu Pilot mission planner.
  • link the receiver and set that up on standard plane mode 2.
  • Connect PM07 Power module, calibrate voltage and current to correct reading in mission planner.
  • Link up the SIK Radios and get comms.
  • Connect GPS and get a fixed position.

Items Im just not getting right

  • I2C Airspeed sensor or pressure sensor to be found?
  • Airspeed used is a 4525D tried with and without a level converter but even if i scope the I2CA & B channels on the PX4 i only get a +3.3VDC on SDA and SCL lines with which seems like no comms also scoped sensor and dont get anything either. 2 sensors tested both same results. Cannot seem to find a way to look at the I2C from QGC or see results of fail?
  • Pressure and humidity sensors are the BMP180 and BME280. Same test as above same result.
  • Have not dealt with the servo out yet but that seems straight forward.
  • Also battling to find info on the physical layout of the PX4 like plug pin out descriptions. Any links to that?

Once i have this up and running I can install into the ship test functionalities and start on the irridium units.

Your assistance would be greatly appreciated as I am an electronic engineer but new to the PX4 system.


Just to clarify: Pixhawk is the hardware. PX4 would be the autopilot used together with QGC (the ground station software). However, you write that you use the ArduPilot mission planner. So are you also using the ArduPilot autopilot software?

If yes then this is the wrong forum because it is about the PX4 autopilot. But you might want to consider switching because I don’t know if the Iridium module is supported in ArduPilot.

With respect to the hardware make sure that you have hardware supported by the PX4 flight stack. I assume by 4525D you mean MS4525 and the BME280 should actually mean BMP280, if yes, then there exist drivers in the PX4 flight stack.

I would suggest that you open a new post with all those issues because now it is not really anymore about the iridium communication.

Ok well I will definitely get back to you then when I start with the irridium.

With regards to Ardupilot I just wanted to see whether I could get the sensors running through another user interface but yes I am using the Pixhawk 4 hardware with QGC and the firmware I loaded onto the Pixhawk hardware was through QGC.

Airspeed yes it is the MS version and with regards to the other sensors it was a package we bought from HolyBro and just checked the pressure sensor again it is clearly a BME marking on the board.

Ok so I will open up another topic and get back to you when I reach the irridium part. Thanks


Just a note to check where I would start on the iridium setup. I have the following. QGC on a PC with a Pixhawk 4. Installed software I am trying to upgrade to version 1.9 but as it does not appear in the upgrade list and the custom firmware upgrade is looking for .px4 file or .bin if i recall. The software I downloaded off Github is just a group of folders which QGC does not recognize.

Ok so the sattelite modules are as follows:

Ground Unit
RockBlock +
12/24VDC, RS232
FCC ID Q639602A

Air Unit
Iridium Satelite LLC
Rock Seven
Rockblock V2.B

Before I get stuck in some tips and tricks and starting point Would be great!


If you download the code from github you first have to build the code and then flash it to the Pixhawk. You could find the instructions here.

By Rockblock V2 you refer to the MK2, right? The implemented system works with the MK2 and the 9603. A ground unit is not really required if you use our system. The documentation can be found in the github repo.

Ok Great let me look into the documentation as the above info I have got off the Units themselves so definitely V2.B is written on the board.

But let me read your docs and build the software and once flashed and the docs gone through I can give you a shout.

Hi great read the docs on the irridium setup but really short and as I have not done this before is there any more detailed docs for a step by step setup?

Looks as if my irridium module is a 9602 will this work?

If it is this one it will work, we used it before we switched to the new version.

Yes thats it.

Ok just loaded Ubuntu and Q Ground Control. Linked up the PX4 to PC and now busy with linking the irridium module to the Pixhawk.

I did install the master firmware onto the Pixhawk 4. Anything I missed?

Ok been trying to find some sort of wiring diagram for the 9602, has pin outs but nothing that clearly indicates UART, rather TX and RX is this it and what logic level does the 9602 operate from? 5V or 3.3V if 5V then a converter would be necessary. I have this not a problem but could not get the UART ports to function on the pixhawk and can see myself having the same problem here.

Connection diagram from the irridium to pixhawk would be great.

Thanks for all the help.

After reading the docs I think the 9602 needs to be powered with 5V. The 9603 could be powered by 3.7V.

However, the power source cannot be the Pixhawk as most of the ports cannot provide enough power (5V with up to 0.5 A required). We use a custom power board to power the all our avionics. It is important that the Pixhawk and the 9602 have the same ground level because otherwise the communication might fail. Apart from the power source you only need to connect the TX and RX to the respective ports on the Pixhawk. Just be careful because they do not follow the standard naming of the TX/RX pins.

Unfortunately we do not have a connection diagram.