Understanding decoding unknown protocols from 433mhz receivers.

[optoisolated]

Hi all,

I'm trying to understand how best to go about trying to decode and understand an relatively unknown serial bitstream I'm receiving on a 433MHz receiver, extracted from Fine Offset WH3018 Weather Station. I've seen similar projects for the WH1080 series, but this model seems very different. It's not helped that I've not really tried to decode unknown bitstreams before, or even how to capture it using something like an Arduino to prototype a replacement display for it.

The receiver module has the 3 obligatory pins; Data, VCC and GND. I've powered it, and connected data to an Arduino module and to a Logic Analyser. I'm struggling to understand the packet structure though. They seem to come in big of 6 second blocks. Or at least there's a blanking period of about ~140ms every 6 seconds. I seriously doubt the packets are that big, but i can't see any logical delineation for the ending of the bitstream so I don't really know where to start decoding this thing. I've attached some screenshots of the logic analyser output for example.



I am expecting to see something along the lines of this, with perhaps one or two extra nibbles for the Solar reading, which the 1080 lacks. It makes sense it would be similar to the 1080 as it's just an evolution of the same unit.



I have a rough idea of the sort of data that will be coming in (basic weather info from the transmitter outside, including wind speed, wind direction (in the form of one of 8 directions NNE, NE etc), outside temp, humidity, solar output, battery check, and I believe (if it's anything like the 1080, starting with a preamble, an ID, and then ending with some form of checksum).

Any guidance or advice on how to approach this problem would be greatly appreciated.

Thanks

[optoisolated]

I've done some more digging and I think I may be approaching this the wrong way. I am going to deconstruct the transmitter and see what I can glean from that end; i think these transmitters are going to be hard to sort out actual data from general noise as I don't see any way for it to do any carrier discrimination when the unit isn't being transmitted to. Once I get my head around how the transmitter is being triggered and what the data packet actually is (Especially the header) I will be in a far better position to figure out the receiver.

[electricMN]

I'm not sure if this will help but I'll throw it out there in hopes that it will.

https://www.sevenwatt.com/main/wh1080-protocol-v2-fsk/