Patent ID: 8243776

Claim:
A communication device, comprising: a communication antenna that receives a transmission signal where a spectrum spread signal subjected to a spectrum spread is modulated; an intermediate frequency converting unit that converts the transmission signal received by the communication antenna into an intermediate frequency signal having a predetermined frequency; an analog to digital converting unit that discretizes the intermediate frequency signal and outputs a discretization signal; a noise removing unit that detects a noise other than a normal thermal noise included in the discretization signal and removes the detected noise from the discretization signal; wherein the noise removing unit includes: a Fourier transforming unit that performs a fast Fourier transform on the discretization signal; a frequency detecting unit that detects a frequency whose amplitude is a predetermined value or more as a peak frequency of the noise, based on a result of the fast Fourier transform in the Fourier transforming unit; a notch filter that sets the peak frequency detected in the frequency detecting unit as a notch frequency, and outputs a discretization signal where a frequency component corresponding to the set notch frequency is attenuated based on the discretization signal; and an adaptive filter that outputs a discretization signal that minimizes a mean squared error with respect to an ideal discretization signal in an ideal state not including the noise; a demodulating unit that demodulates the spectrum spread signal, based on the discretization signal that is output from the noise removing unit; a level detecting unit that detects an average value or an integration value in a predetermined time of the discretization signal; and an adjustment signal output unit that outputs an adjustment signal to selectively operate the notch filter and the adaptive filter, based on the average value or the integration value detected by the level detecting unit and a predetermined threshold value.