Patent ID: 7652527
Filing Date: 2010-01-26
Classification: H04L

Abstract:
1. A demodulator comprising: a plurality of demodulating units configured with gain setting units for outputting gain setting signals that set gains in adjusting the signal levels of inputted orthogonal frequency division multiplexing signals to predetermined signal levels, the plurality of demodulating units for demodulating inputted orthogonal frequency division multiplexing signals whose levels have been adjusted to the predetermined signal levels, and outputting demodulated signals; comparing units for comparing the gain setting signals outputted from the gain setting units in each demodulating unit; noise component calculating units provided for each demodulating unit, for calculating noise components included in the demodulated signals outputted from corresponding demodulating unit; channel profile calculating units provided for each demodulating unit, for calculating channel profiles based upon the demodulated signals outputted from corresponding demodulating unit; transmission channel decision units for determining transmission channels based upon the channel profiles; reliability information generating units for generating reliability information indicating reliability of the demodulated signals outputted from each demodulating unit, based upon the results of the comparison by the comparing unit, upon the results of the determinations by the transmission channel decision units, and upon the noise components; a weighting factor calculating unit for calculating, depending on the reliability information, weighting factors used in combining the demodulated signals outputted from each demodulating unit; and a combining unit for combining, in proportion to the weighting factors, the demodulated signals outputted from each demodulating unit, wherein each of the noise component calculating units comprises: a pilot signal extracting unit for extracting pilot signals from the demodulated signals outputted from each of the demodulating units; a signal error calculation unit for calculating a plurality of differences between the signal levels of the pilot signals and the signal levels of predetermined given signals; and an average error calculation unit for averaging the plurality of differences calculated during a predetermined time period in the signal error calculation unit, and for outputting the averaged result as one of the noise components.