Spectrum agile radio

摘要

A spectrum agile radio having one or more variable digital filters is described. To quickly, yet accurately, retune the digital filter(s) a windowing function is applied to an ideal filter characteristic for each of one or more desired frequency bands to generate filter coefficients. Transitioning between coefficients of a previous filter and a current filter is handled to avoid problems associated with discontinuities in the signal processing.

主权项

1. A method for modifying coefficients of a digital filter in a communication node for filtering a signal present in a frequency sub-band the method comprising:
filtering the signal over a frequency band which includes the frequency sub-band; determining an ideal filter function for the frequency band; performing an inverse Fourier transform on the ideal filter function to generate initial coefficients; multiplying the initial coefficients by a windowing function provided for the frequency sub-band to generate final filter coefficients; and substituting said final filter coefficients for previous coefficients of said digital filter.