| 摘要 |
PURPOSE:To reduce the digital operation quantity to avoid complication of the device, by performing N/2-point Fourier conversion twice in stead of one-time N-point Fourier conversion in the device which receives the multichannel amplitude modulation signal multiplexed orthogonally. CONSTITUTION:The receiving signal input to input terminal 12 is sampled in sampler 13 by the sampling frequency 1/NTHz and is separated into sample value sequences for every T/2sec by multiplexing separating circuit 14, and the n-th sample value is input to input terminal 15n. This sample value is subjected to frequency shift by preprocessing circuit 16 and becomes N/2-point complex sample values 17i and 18i. These complex sample values 17i and 18i are constituted by N/2-number actual low-pass filters where the one-side effective band width is 1/2THz and only the linear phase inclination is different in steps. They are subjected to N/2-point offset Fourier conversion at every T/2sec through polyphase circuits 19 and 20 by offset Fourier converters 23 and 24 and are output from post-processing circuit 27. |
