Patent ID: 9306718
Filing Date: 2016-04-05
CPC Classification: H04B,H04L

Claim Text:
1. A method for mitigating helicopter rotor blockage of communications comprising: receiving a signal comprising frames of data, wherein the frames of data contain regularly spaced pilot symbols; Fast Fourier Transforming (FFT) pilot symbols of one current frame of data of a series of at least one frame of data; implementing a time delay of one frame; applying a forgetting factor to an accumulated spectrum, wherein the forgetting factor is a factor of less than one, wherein the accumulated spectrum is a FFT of at least one previous frame of data of a series of at least one frame of data; performing a leaky coherent integration, wherein the leaky coherent integration adds a result of the FFT of the one current frame of data to the accumulated spectrum; calculating a threshold, wherein the threshold is based on a mean energy of all FFT bins in the accumulated spectrum, wherein FFT bins are characterized by a discrete range of frequencies along the accumulated spectrum; masking the FFT bins, wherein masking comprises retaining only FFT bins that exceed the threshold and above a minimum expected rotor blocking frequency and adjacent FFT bins; inverse FFT the accumulated spectrum; erasing pilot symbols below the threshold by removing the pilot symbols from signal parameter estimation; erasing data symbols that lie in a blockage by setting bit-log likelihood ratios to zero.