This invention relates to signal processing, and more particularly to a digital signal processing apparatus.
A sensed video signal or a detected signal, for example, an electrocardiogram signal is in many cases subjected to a special filtering process, for example, a differentiation filtering process and a smoothing filtering process for various analyses. These filtering processes are carried out at present using digital techniques. In order to filter a digital signal represented by a discrete time-series signal, multiplication and division processes are generally required. When such filtering process is done by means of software with a minicomputer or a microcomputer in accordance with a prior art technique, the filtering process such as the multiplication and division processes is performed by repeated calculation steps, which require a great deal of processing time. Therefore, it is difficult to carry out such filtering process in real time base by the software. On the other hand, when such filtering process is performed by means of a specific hardware, a complicated circuit configuration is required. Further, since a computation speed is influenced by data length of the digital signal, highly-accurate computation circuit elements are required.
In the prior art described above, different circuit configurations are required for different filtering processes, such as differentiation and smoothing processes. Since such different circuit configurations require different processing times, output signals having different time phases are delivered therefrom when an input digital signal represented by the time-series signal is inputted into different filters at the same instant. In other words, it is difficult to synchronize these output signals delivered from the different filters with each other.