| 摘要 |
PROBLEM TO BE SOLVED: To form a sub-band having an optional frequency width from an optional frequency, reduce the sampling frequency so as to be flexibly respondable to applications. SOLUTION: From the input signal from a terminal 101, high-pass side signal is taken out by a LPF(low pass filter) 102 and a subtracter 106, and this signal is FFT-processed by a FFT(fast Fourier-transformation) circuit 161, converted into a signal on frequency axis, and shifted to the other position of other band on frequency axis by a frequency shift circuit 162. A reverse orthogonal transformation is performed by a reverse FFT circuit 163 to convert the signal into a signal on time base, and the signal on time axis subjected to reverse orthogonal transformation is coded, whereby a coding processing can be performed at a low sampling frequency. |
