Patent ID: 8036100

Claim:
A digital signal demultiplexing apparatus for demultiplexing an input signal in which signals of a plurality of channels are frequency-multiplexed, comprising: a first unit configured to perform discrete Fourier transform on the input signal to output samples of the frequency domain; a second unit configured to output, for each channel of the plurality of channels, all samples existing within a frequency band of the respective channel from the samples of the frequency domain, the frequency band corresponding to a frequency and a bandwidth of the respective channel, the plurality of channels including at least one channel having a number of samples different from a number of samples of another channel; a third unit configured to add samples such that a number of samples of each channel output from the second unit becomes a power of two; a fourth unit configured, for each channel of the plurality of channels, to perform, on the samples of the respective channel made to be the power of two, discrete inverse Fourier transform of a length that is equal to the number of the samples of the respective channel so as to output a time domain signal into a memory corresponding to the respective channel; and a fifth unit configured to output a signal of each channel demultiplexed from the input signal by reading out the time domain signal from the memory corresponding to the respective channel at a rate corresponding to the bandwidth of the respective channel.