An analog/hybrid real-time continuous signal processing system based on an analog delay line is proposed and discussed. In this system the input signal f(t) is fed to the delay line to obtain the parallel signals f(t-nΔτ)'s from its intermediate taps, and then various operations are applied to those signals by parallel analog circuits under the supervision of a digital mini-computer. The system operates on the principle of the FFT-based signal processing technique used widely at present, and shares its merit. Besides, the parallel analog circuit is capable of continuous high speed processing of an input signal.
A delay-line-based nonrecursive convoluter is actually constructed. An electric circuitry to realize an accurate analog delay line is shown. The FFT-based method of determining values of weighting coefficients of the convoluter to approximate a desired frequency response is also shown. According to this method, filters having various frequency responses are synthesized by the convolutes. Some examples of synthesis are shown. These results agreed well with theoretical computations. It is concluded that such systems are practical, and especially advantageous in picture processing, though the pilot system is designed for audio frequencies.