You see this stuff by jimmie wong?
it’s with the nRF sdk but good info and code insite…
HTH
GL 
PJ
This is the secret sauce IMO
Fig 4. BLE coding and modulation schemes
For 1Mbs and 2Mbs this remains the case, however for the longer range options (LE coded) of
500kbs and 125kbs, this changes. As can be seen in fig 4. The payloads have multiple symbols
for each bit, S = 2 for 500kbs and S = 8 for 125kbs (where S is the symbol/bit rate), this in
essence means more symbols per bit allows more tolerance with a poor signal to noise ratio,
and still provide a recoverable data stream. In short this allows a receiver to correct bit errors
on the receiving side of a communication link.
This process happens entirely in hardware and is transparent to the developer.
The required data rate is chosen and packets arrive and are delivered by the
SoftDevice to the application in the same way regardless of on-air data rate.
Fig 5 shows the system blocks for data processing for uncoded and coded
PHY on the TX and RX sides.
Good basic short video of Coded PHY and the more power required because transmitter is on long to sen dat at lower 125k rate.
