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merbanan / rtl_433

Program to decode radio transmissions from devices on the ISM bands (and other frequencies)
GNU General Public License v2.0
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Wmbus device type 104, using different frequency and different transmission speed #2857

Closed jacksonlancaster closed 8 months ago

jacksonlancaster commented 8 months ago

I have a wireless mbus device that uses 915MHz and 250kbps transmission rate. It sends data in C1 format. Since it's non standard freq and speed, how would I read this? Any parameters I can change or code I can modify to accommodate this?

zuckschwerdt commented 8 months ago

Frequency is no problem, just use a fitting -f.

The rate is pretty high, you'd need to adjust short and long here: https://github.com/merbanan/rtl_433/blob/master/src/devices/m_bus.c#L1217 and then use a high sample rate.

jacksonlancaster commented 8 months ago

I changed the short width. Any idea what the long_width should be set to in the case of 250kbps?

.short_width = 25, // Bit rate: 250kb/s .long_width = 10, // NRZ encoding (bit width = pulse width)

ProfBoc75 commented 8 months ago

Hi @jacksonlancaster : this is less, at 250kb/s the pulse duration is 4 µs, and because of PCM , short = long = 4 it's very short, as @zuckschwerdt said you have to increase the sample rate too with -s 2048k for example.

jacksonlancaster commented 8 months ago

Do I also need to change the .reset_limit = 500 to a different value?

ProfBoc75 commented 8 months ago

Yes, you can reduce with r = 200 to keep same ratio. Up to you to update the value.

If you want to test, you can use the flex decoder until you have a good result then you apply your findings into the decoder. Because each time you update the c file you need to compile, then to test, correct again , compile , test, .... Lot of time to get the figures.

jacksonlancaster commented 8 months ago

Thank you guys so much. I was able to get it to read!