Patent ID: 6215828
Filing Date: 2001-04-10
Classification: H03H,H04J,H04L

Abstract:
An apparatus for transforming a real digital wideband high-frequency signal into a set of complex digital baseband signals, comprising:a set of complex digital bandpass filters for filtering the real digital wideband high frequency signal into a corresponding set of complex signals, each complex signal having an I component and a Q component, wherein each complex digital bandpass filters is formed by a real digital lowpass filter that has been transformed into a complex digital bandpass filter through a transformation of its digital lowpass filter transfer function into a complex digital bandpass filter transfer function, and has substantially non-overlapping narrow passbands for separating said real digital wideband high-frequency signal into a set of complex digital narrowband high-frequency signals; andmeans for converting said set of complex digital narrowband high-frequency signals into said set of complex digital baseband signals by first down-sampling and then low-pass filtering each complex digital narrowband high-frequency signal into a corresponding complex digital baseband signal.