Figure 3.

Communication in presence of noise. Principle limitations of communication in presence of noise are given by Shannon’s theorem, which shows the relation between bandwidth, signal-to-noise ratio and theoretical capacity of a communication channel. Curves displayed in the graph show comparison of frequency bandwidths required for communication under given noise circumstances. Each line corresponds to certain speed of information transfer. Signal-to-noise ratio was calculated for average emission of 100 photons/second.