For the C1121 what is the change in receiver sensitivity when changing from 2-GFSK to 4-GFSK ? (Assuming nothing else changes)
I get a figure of around 4.8dB based on the fact that 4-GFSK has 4 levels on the eye diagram and 2-GFSk only has 2. This means the impact of noise increases by about 3 times for GFSK.
This is only applicable if the frequency deviation is large to start with. If the modulation index is less then or equal to 1 is this still applicable? This would mean the inner symbols would have a modulation index of less then 0.33. Can the receiver still easily decode these sysmbols or are we getting to the point where thing start falling apart.
If we take this further and have GMSK (2-GFSK with modulation index of 0.5) and we change the receiver to 4-GFSK we get a modulation index of 0.165 for the inner symbols. Will the S/N drop still hold or is it going to be much bigger ?