@ Dennis,
The short answer is the same way I sorted out the what/where/how for the tx/rx frequency bytes, a lot of perseverence, spreadsheet tables, and some serendipitous luck.
If spreadsheets were actually sheets of paper and I owned a paper mill, I'd be my best customer, and broker than I already am.
Finding what/where/how the RSS dealt with PL data was a big part of it. First, I had to get the hex data associated with the entered PL code and the RSS wasnt giving that secret up without a fight.
With the indexed delete/shuffle/move and orphaning of PL codes, the more I changed the codeplug to see a difference, the more cluttered it got with identical, but non indexed values in memory locations that made no sense.
Once I established an abreviated table of codes=values, I could see no association with the X's formula. Even inverting some/part/all, swapping bytes, nothing lined up.
I gave up on that path shortly since the tx/rx freq storage was so different why expect the PL method to match either.
Foutunately the RSS allows .1hz resolution entry which let me build formulas in Excel that could be tightly incremented and analyzed.
Excel is good with that because you can do a dectobin or hextobin conversion and see bit level changes and patterns you cant (or at least I cant) envision in hex or decimal.
I knew there had to be a multiplier like the X does, so I just started with different sets of values until things began to line up.
The cool thing about Excel is it really good like that in that once you set up your formulas, you can do a lot of columns of "drag to increment" and convert the data to columns of various formats at the same time.
I guess you could call it a form of brute force attack.
I dont recall if it was the tx or rx first but I hit pay dirt when the the lower half of byte1 and all of byte2 started consistantly matching the RSS value. It took a while longer to get the other mutiplier but it finally worked out.
I had to experiment quite a bit with the resolution as Excel's floating point function is about as good as a $8 calculator from Walmart.
The math cosistantly adds up to the RSS calcs so it must be close.
