Communication device, noise removing method, and program

A noise removing method that can use a communication device comprising a display unit, an operating unit coupled to the display unit, a communication antenna coupled to a control unit, wherein the communication antenna receives a transmission signal where a spectrum spread signal subjected to a spectrum spread is modulated, at least one processor, coupled to the operation unit and the display unit, configured to convert the transmission signal received by the communication antenna into an intermediate frequency signal having a predetermined frequency, and an analog to digital converting unit that discretizes the intermediate frequency signal and outputs a discretization signal, and removes a noise other than a normal thermal noise included in the discretization signal, the noise removing method comprising the steps of:

• performing a fast Fourier transform on the discretization signal and deriving a power spectrum based on a result of the fast Fourier transform;
• selectively outputting the result of the fast Fourier transform or the power spectrum derived from the result of the fast Fourier transform, based on the result of the fast Fourier transform and the power spectrum;
• outputting a discretization signal that minimizes a mean squared error with respect to an ideal discretization signal in an ideal state not including the noise, based on the discretization signal derived from the power spectrum and a reference power per unit frequency, when the power spectrum is output;
• and
• performing an inversed fast Fourier transform on the result of the fast Fourier transform or the discretization signal.

A non-transitory, computer-readable medium having stored thereon a computer program that, when executed by a computer, causes the computer to perform a method, the method comprising:

• performing a fast Fourier transform on a discretization signal and deriving a power spectrum based on a result of the fast Fourier transform;
• selectively outputting the result of the fast Fourier transform or the power spectrum derived from the result of the fast Fourier transform, based on the result of the fast Fourier transform and the power spectrum;
• outputting a discretization signal that minimizes a mean squared error with respect to an ideal discretization signal in an ideal state not including noise, based on the power spectrum and a reference power per unit frequency, when the power spectrum is output;
• and
• performing an inversed fast Fourier transform on the result of the fast Fourier transform or the discretization signal.