Patent ID: 6583906
Filing Date: 2003-06-24
Classification: H04B

Abstract:
A signal pre-processor for laser communications, comprising:a source of an output signal, the output signal having high frequency positive and negative excursions in amplitude with respect to an average amplitude, with an extent of some excursions being larger than other excursions; a preshaper that is configured to transform the output signal, including reducing the extent of larger negative excursions with respect to other excursions in the output signal, to produce therefrom a transformed signal that includes a transformed portion of the larger negative excursions that facilitates a reconstruction of the larger negative excursions at a receiving system, so as to increase a modulation index associated with a modulation of the output signal; a bias device that is configured to bias an average amplitude of the transformed signal by approximately a minimum amount required, to produce therefrom a biased transformed signal so that an amplitude of the biased transformed signal during negative excursions does not fall below a predetermined minimum positive amplitude, to produce therefrom a biased and transformed output signal that is suitable for modulating a laser beam to produce therefrom a modulated laser beam.