Method for simultaneous equalization, fractional delay and filtering for coherent combining of distributed antenna signals

Abstract

Systems and methods are provided that derive dynamically adjustable fractional delay, frequency equalization and bandpass filtering for coherent combining of distributed antenna signals. The systems and methods include functions that dynamically adjust the coefficients of a single filter component of a signal channel to adapt to current environment variables affecting signals both resident within a single channel and resident across multiple channels being combined. This includes measuring frequency response characteristics at an output of an intermediate frequency channel and deriving sets of coefficients. Each set of coefficients provides a unique delay that is a fraction of a sample clock period that when loaded in a digital filter induces a fractional delay in a signal being filtered by the digital filter. Preferably, weighted average filtering of equally spaced intermediate frequency spectral frequency measurements is included.