RFM69HW 868MHz working on 915MHz



  • Anyone here with experience on using RFM69HW radios marked or 868MHz tune via software to operate on 915MHz?
    I ordered several of them to replace some long-distance NRF24L01 sensors that I had problems with, and it seems they interfere with my wireless alarm system, which constantly complains about possible interference and starts blaring at odd times...
    I know they work, but I don't know if it is advisable to operate at a different frequency, either for transmitter life expentacy, or spurious harmonics and what not.
    Thanks in advance.



  • @kted The chip can work on different frequencies, but the discrete parts and the antenna are tuned for this frequency.
    As the frequencies you want to try are quite close, the discrete parts are the same and changing the frequency is a matter of settings in the chip. So a different sketch. And perhaps cut your antenna a bit.

    check https://youtu.be/soaE5X6_aRk



  • @electrik They work fine if I just change the frequency definition from RFM69_868MHZ to RFM69_915MHZ, but I don't know if the frequency actually changes. Currently I'm waiting for an RTL-SDR dongle to arrive, so I can make some tests to be sure...



  • @kted did it make a difference with the interferences you had?



  • @electrik I didn't modify the whole network, just two nodes as a receiver and transmitter. I'm waiting for the SDR-RTL first...



  • @kted Felix @ lowpowerlab sells only 915Mhz (and 433Mhz) as he says it is the same as 868Mhz variant. You may want to ask at lowpowerlab forum, but there is no downside at all.



  • I accidentally used a 915 MHz part at 433 MHz and even that worked, albeit at substantially reduced range.


 

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