[email protected] writes: > I found a correlation formula between the RFM69 frequencies and my EU > trial-and-error frequency set. > > rtldavis frequency = (RFM69 frequency -40000000) * 1,048319523 > > These calculated rtldavis frequencies DO work! > > Excel gave the following equation: y = 1.0439x - 4E+07, but the factor was > not precise enough. > > The results: > > RFM69 rtldavis > 868066711 868078500 > 868181885 868199238 > 868297119 868320041 > 868412292 868440779 > 868527466 868561518
It would be interesting to really understand what's going on. It seems like the "RFM69 frequencies" are what is programmed into the transmitter, and I wonder if that is the intended transmit frequency or if there is some IF involved. It would be interesting to also sniff the RFM69 receive chip frequencies at the console. And, to measure the actual frequencies with test equipment, or something that can be relied upon to be reaosnably accurate because of calibration. When I saw the formula above, I suspected a 40 MHz IF and was suspicious of the 1.048ish factor. But I wonder what that would look like if it were fit with different assumptions about the base formula. Overall, something seems wrong in code somewhere, as a change of 12 kHz offset to a 35 kHz offset over 500 kHz does not seem plausible. I'll try to run this and see if I can spot anything.
