Jens David wrote: > You use the shannon formula for channel capacity, insert 15 dB S/N > and 25 KHz bandwith. This gives you a theoretical maximum capacity > of about 125 Kbps. You you know of any amateur radio equipment which > is able to achieve this? The answer is for sure no. The truth is, > this capacity is vitally unreachable. However, by means of high > efficient channel coding (e.g. turbo codes) you can reach that > limit by about 0.5 dB (S/N). At our current setup, if you receive You are assuming an AWGN channel model. With amateur FM transceivers, this model is very inaccurate. First, there is quite severe nonlinear distortion in the modulator, second, the noise after the FM demodulator is not gaussian. Tom
