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AssigneeFairwinds Technologies, LLC
InventorsPavlo Bobrek, Keith Adams
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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.
A method for generating the coefficients for a digital filter that concurrently performs bandlimiting, channel frequency equalization and fractional delay compensation including:
A method for dynamically tracking and compensating for delay variations between two channels that are to be coherently combined to improve the signal to noise ratio for downstream receiving modems, including using an adaptive delay estimator.
A system configured to generate the coefficients for a digital filter that concurrently performs bandlimiting, channel frequency equalization and fractional delay compensation, including:
A system for dynamically tracking and compensating for delay variations between two channels that are to be coherently combined to improve the signal to noise ratio for downstream receiving modems, including an adaptive delay estimator to provide a coarse delay estimate between two input channels of a digital combiner.
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