Thanks Mark for getting me to read this thread again.
I'm still overwhelmed by the volume of information and relationships between all the parameters, I am starting to understand a little more.
Since this part of my project will be hardwired, battery usage is not an issue. Also range is no as important but not negligible. I've managed to get the Semtech starter kit running but there are still some aspects of relationships that are still foggy. For example for a given bitrate, lets say 250 kbps, there is a range of valid FDev values but I don't quite get which way does what. what is the impact of having a Fdev value on the low side compared to having it on the high side of the valid Fdev range.
What I'm also struggling with is what to concentrate on first. There are many parameters to consider. Am I correct that I should learn in the order of the rules ?
Here what I understand and are some of the questions I'm trying to answer:
Rule 1) 0.5 <= 2 * Fdev/BR <= 10 (modulation index, MI)
This is for transmitting ?, do I want to be closer to 0.5 or to 10 ?
Rule 2) BR < 2*RxBw (bit rate)
This determines the maximum biterate relationship between the transmitter and the receiver. Having the BR closer to 2*RxBw rather than further away will have what consequences ?
Rule 3) RxBw >= Fdev + BR/2 (receiver bandwidth)
Pretty sure this sets the receiver settings limits. Should it be set as close to the limit as possible ?
Rule 4) RxBwAfc >= Fdev + BR/2 + LOoffset (receiver AFC bandwidth)
This rule is only applicable if AFC is enabled. I haven't looked into that much yet, so I'm not sure what AFC does except for the basic definition. But I think I can look into that last.
Rule 5) Fdev + BR/2 < 500kHz (maximum RxBw setting)
This one a simply a hard limit to the RxBw setting. I think that this rules means that what ever values you choose in the 4 previous rules This rule can't be broken.
What should I try to figure out first ?