Hisato Fujisaka

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The paper describes a digital circuit technique to process directly bit-stream signals from sigmadelta modulation based analogue-to-digital converters and the application of the technique to communication systems. The newly developed adder and multiplier are fundamental processing circuit modules. Using the fundamental modules and up/down counters, other(More)
Recently time-frequency interferometry (TFI)OFDM has been proposed as a channel identification scheme. TFI-OFDM system can multiplex the same impulse response in twice on the time domain without overlapping to each other. In this case, the required pilot signal is only one. Moreover, by averaging of these impulse responses, the accurated channel impulse(More)
A digital wave filter operating on bandpass sigma-delta (SD) modulated signals is presented in this paper. The filter is obtained by a z-domain transformation of a baseband SD domain filter which is a binary-quantized discrete model of an analog distributed parameter filter (ADPF). Thus, the design properties of various ADPFs can be utilized for(More)
This paper presents a sigma-delta domain bandpass digital filter built by using single-electron tunneling (SET) devices. The filter is a spatiotemporally discretized and binary quantized model of analog distributed parameter filters. The discretized and quantized model naturally has local connection structure and fault tolerance of transient device errors.(More)
This paper describes a deterministic two-layer cellular array in which many virtual particles move pseudorandomly. The motion of the particles is defined by a two-state Markov chain. A parameter of the cellular array determines the eigenvalue of the transition matrix which defines the Markov chain. Thus, the cellular array can generate pseudorandom binary(More)
In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. In such channels, severe fading of the signal amplitude and inter-symbol-interference (ISI) due to the frequency selectivity of the channel cause an unacceptable degradation of error performance. Orthogonal frequency division multiplexing (OFDM) is an(More)