SIK Radio Setup Question

Haven’t touched SIK radios in a long time and running into a connection issue. Not sure what setting I need to change.


  1. From this link, which firmware to use and how one determines which firmware is for what SIK radio? The ones I have are I think are Chinese clones.

  1. SIK Radio receiver is connected to TELEMETRY 1 on Pixhawk.

  2. Using all 4 wires, that is GND, +5V, RX and TX.

  3. Should I be using MAVLINK 1 or 2? or NONE?

  4. baud rate should be 57 or 115?

Inside mission planner the TELEMETRY 1 settings are as follows:

If I recall from past discussions, the SIK receiver connected to Pixhawk firmware can only be updated using a USB to TTL converter. Am I right?

What software do I use to update the receiver SIK radio firmware? “or” just connect the SIK receiver to Laptop USB port and do an update?

1- Updates I do just from mission planner. They will do the latest SIK hardware.

2- You can connect the radios to any UART. So Telemetry 1 is perfect. That’s usually SERIAL1

3- Remember TX<>RX and RX<>TX.

4- Mavlink 1 or 2 will work. With the clones maybe 1 might be better, but you can try both.

5- Baud 57.

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MAVLINK2 is preferred since there’s features that dont work with MAVLINK1, and no downside to using it. Ardupilot defaults to MAVLINK2 now.
Probably one of the only devices that relies on MAVLINK1 is an old-style OSD add-on board.


@Allister @xfacta

Thanks guys…finally managed to make them work.

I switched back to 1.9 and the other mistake I was making that on the receiver radio, I did not have OPP resend and ECC boxes checked. After reading some documentation it is recommended not to enable ECC as it reduces the the Air Speed by half.

Save settings and power cycle is critical else nothing works.


I am going to now try 2.2 firmware and see what happens. It suppose to have some bug fixes.


  1. What is the purpose of these two features (circled in red)? not finding any documentation.

  2. On my computer it doesn’t let me check AES Encryption. Can guys enable it on yours?

“or” are these features only available for specific type of SIK radios supported by Ardupilot?

p.s. tested 2.2 version, works really well. makes a better stable connection compare to 1.9

In normal use you should NOT have op resend or ECC checked.
About the most we need to do is reread (download) a freshly uploaded mission to ensure the FC has what we expect, or reread parameters to ensure changes actually too place.
When not using RTS/CTS I also set BRD_SER1_RTSCTS,0 just to make sure the Auto value doesnt get mistaken and try to use RTS/CTS

  • Op resend - keeps resending any dropped/missing packets whenever possible - best to ignore missing packets in our case because the following packets contain all new data making the missed packets obsolete
  • ECC - error correction - does halve the effective amount of data that can be transmitted, see op resend reasoning

You would only use those two option in some high security / high reliability environment , and you would probably also increase the baud rate (and air rate) to suit.

The RCIN and RCOUT options are usually only available on the RFD radios, I’ve not seen any of the 3DR type radios (or copies) where you can use them. With the RFD900X and UX you can pass through your RC control and even specify PWM or SBUS differently at each end and the radios will convert. SBUS is preferred at both ends obviously. The advantage is you would have only one radio on your aircraft for both telemetry and RC control - the RFD radios give you diversity antennas and long range, much longer than any normal RC system.

Also, I’ve got old 433MHz radios running at 115k baud so you could try that too :slight_smile: although it might be that not all radios will allow setting of the required values. I cant say how it affected range because I dont fly with these radios, only ground testing. The RFD900X’s do long range with these settings.
SiK 2.2 on HM-TRP
Baud 115200
Air speed 128
Max Window 80

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Thanks. This is an interesting point you have raised. So this means inside mission planner SIK Radio settings when you uncheck the RTS/CTS doesn’t update the above parameter?

I am using these radios for a ROVER so long distance is not needed.

I do have some RFD900s which I use for VTOLs so totally agree with you on your suggestions and observations. I never tested these features though, I will try them. Thanks

By the way I wanted ask you and @Allister if you two would be interested in working on developing BiDou (Chinese Satellite system) SIK RADIO which provides FREE text messaging (tested by one guy in Australia) for BVLOS as a secondary telemetry data gathering. Yes, I am aware off the shelf system but its a paid subscription and gets very costly. I found a development board on AliExpress and BiDou has forum on FB to get development help.

Next we can work on SpaceX satellites (I have some connections there).

If interested we three can chat offline (I will provide funding for the hardware).

p.s. What about AES encryption? Is that feature also relevant to RFD900s?

I dont think I can do the Beidou messaging work, but I appreciate the offer.

The RFDs do handle encryption nicely.

Correct - the SIK radio settings are independent of the Ardupilot parameters, so it’s doubly easy to make everything stop working :slight_smile: got to get the baud rates and all matched.

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watch this video. He made it work with BeiDou. I asked him if he can provide some guidance but he is too lazy to respond :slight_smile:

I want to do similar mission with my solar glider just for the kicks and giggles!

Suppose to do 4hr flight with a single 2200mAh battery. I want to fly it over Lake Michigan.

Interesting idea. Out of my ability for development, but testing could be interesting. I have to admit I’m not sure I understand how you can text on BiDou. I always assumed that was just one-way GNSS system.



Its not similar to text messaging we are accustomed to. The packet length is restricted. Its basically short burst of SMS.m from a regular ground phone to the satellite and then you can receive it on the ground anywhere where the satellite signal can be received.

Watch the video I posted about my flydream. He managed to make it work. I exchanged emails with him last year but so far he is not providing any details on how he developed the link to work.

I found these great deals on AliExpress