スプライン関数による適応形デルタ変調を用いた時間関数発生法

抄録

As a zero order hold for a D/A conversion of a conventional digital time function generator is used to approximate a signal between two consecutive sampling instants, many sampling points are necessary to improve the approximation of the continuous signal. Consequently, the frequency range of the generated functions is restricted. For this problem the authors propose a new type of a time function generating method using delta modulation, which consists of a combination of the zero order hold of periodically sampled signals and the interpolation of the signal between its sampling points. In this method the signal between consecutive sampling points is interpolated by the sequences of the optimum positive and negative steps of the delta demodulator. Therefore, it is very important to decide the pulse height of the delta demodulator. The calculation of this pulse height is based on the spline function which estimates the signal between two sampling instants from five sampling data.
The proposed function generating method has such features that the operational circuit of the optimum pulse height can be constructed by only analog adders, since it is caluculated a linear combination of the five sampled data, and that a good accurately approximation of a function and wide frequency range of the generated function can be obtained also.