Patent ID: 6396881
Filing Date: 2002-05-28
Classification: H03D,H04L

Abstract:
An apparatus for complex demodulating a modulated information signal with a demodulation-reference signal, the apparatus comprising:(a) a phase adjuster constructed to receive a digitized version of the demodulation-reference signal, the phase adjuster comprising a first Hilbert transformer and being constructed to apply a phase angle shift to the digitized version of the demodulation-reference signal; (b) a second Hilbert transformer having an input that is operatively coupled to the phase adjuster, the second Hilbert transformer being constructed to generate an in-phase output signal and a quadrature output signal; (c) a gain-controlling circuit constructed to dynamically generate a gain factor to be applied to an output of at least one Hilbert transformer of the apparatus, the gain factor being dynamically generated by the gain-controlling circuit to maintain, during operation of the apparatus, a gain of the at least one Hilbert transformer of the apparatus at a predetermined value; and (d) a demodulator comprising: (1) a compensating delay element connected to receive a digitized version of the modulated information signal and to match a delay of elements (a) through (c) imposed by the apparatus; and (2) a pair of multipliers operatively coupled to the compensating delay element, the pair of multipliers being constructed to perform complex demodulation of the digitized version of the modulated information signal, using the in-phase output and the quadrature output from the second Hilbert transformer.