> Your insight on noise and nonlinearity caught my attention. I have written a
> link budget fora University of Colorado satellite to be launched some time next
> year, and I have assumed AGWN and linearity.
Alexander Kurpiers has made simulations about this AFAIR.
> The setup is for GMSK (G3RUH) modulation @ 9600 bps, and I will be using an
> Icom 821H transceiver.
> I am wondering if you are familiar with how nonlinearities an non-white noise
There are two typical transceiver circuits in use:
- crystal oscillator modulated with a varactor. There, the nonlinearity
stems quite directly from the varactor characteristic
- PLL: here, the PLL compensates the low frequency part of the
modulation,
while a circuit tries to compensate this by modulating the reference
oscillator. I have no model for this, though it seems that you cannot
operate with a linearized PLL model here. And the effects seem to be
strongly dependent on the adjustment of the circuit...
Tom