Fm demodulating device using an extended kalman filter

Abstract

This invention provides an FM demodulating device for robustly demodulating a received FM signal even under a jammed communication condition through the use of an improved extended Kalman filtering scheme, which is applied to the FM communication system exhibiting a random occurrence of cochannel. The device includes a memory for providing scale factors stored therein at an appropriate time, an observation determining unit for analyzing the reliability of the received signal based upon error computation results and scale factors to determine whether or not the received signal contains an interfering signal, and for correcting the received signal, a state predictor predicting states for the corrected observations, a state estimator receiving the error computation results, for producing the calculations performed for the state estimation, and an error computing unit receiving the predicted states from the state predicting means, for calculating the errors, and then outputting the calculated errors to the observation determining unit and state estimator.