I want to decode the exchange between two HC-12, but I can not decode the sequence. I am doing a FSK2 demodulation the spectrum analyser img:

and I arrive at this binary sequence:

But I can not find my basic message, I decode the sequence at the right speed (I make a measurement on the smallest bit) in this case the synchronization sequence.

In the @Mark Hughes tutorial he finds the initial message well, you can see it :

Thank's for your help

Théo

 

Hi Théo @Kanar LeCanard ,
Glad you were able to make a thread! BTW -- is this something you're doing for fun? Part of a larger project?

So a couple of quick things for anyone picking up on the thread later on. The two images linked above intercept the signal at different OSI levels. The second image (Black background with green trace) is Layer 1 -- Théo is intercepting the radio transmissions directly. The third image (Black with AllAboutCircuits shown above binary sequence) is the decoded data after it passes through the radio and the mcu. So the question is how to use the tools that he has to interpret the layer 1 data.

Here is a reference for the packet handler in the Si446: https://www.silabs.com/documents/public/application-notes/AN626.pdf

The published general packet structure is shown below.


Now here comes the fun bit. The spectrum appears to demonstrate a 2(G)FSK spectrum. However, it is unknown whether or not data whitening is enabled, manchester encoding is used, or if there are any other gotchas in the raw data.

Here's some API documentation for the chip as well. http://www.silabs.com/documents/public/application-notes/EZRadioPRO_REVB1_API.zip

Théo -- what tools do you have available to you? Can you capture an entire packet? Do you have access to GNURadio, a JTAG debugger (to read the bitmap in the chip), anything else?

Thanks,
Mark

@ericgibbs This thread may/may not interest you.

 

Hello @Mark Hughes
It is a project for the pleasure that I take seriously.

Ahhhh okay, I understand better how is structured the link, I will study the various documentations and try to decode again with your information.
I'll come back to you as soon as possible.

thanks again.

 

Hi @Kanar LeCanard ,
I don't know if it will be useful to you or not -- but I did an article a little while back on BLE5 bit data paths -- not entirely relevant, but there is a section on data whitening you might find useful.
https://www.allaboutcircuits.com/te...distance-bluetooth-low-energy-bit-data-paths/
I look forward to hearing about your progress. With any luck an RF engineer on this site who has worked with the chip might see this thread and chime in.
Best,
Mark