DIGITAL MEASUREMENT USING SHIFT KEYED SYMBOLS

摘要

The transfer of information theory from data communications to digital measurement in the form of the coding theorems, descriptive languages and data patterns, has provided new digital signals. In this paper, shift keyed symbols are used to design Symbolic Addition (SA), Phase Shift Keyed (PSK) and Frequency Shift Keyed (FSK) signals. These allow different aspects of a frequency response to be investigated with one signal and one experiment. Symmetrical versions of these signals allow a set of Multifrequency Identification Patterns (MIPs) which can capture and monitor different multifrequency characteristics. SA signals are useful for obtaining information at the phase crossover allowing the determination of controller settings in auto-tuning or adaptive control. PSK signals 'zoom in' and give accurate details of, say, a peak in the closed loop frequency response while FSK signals highlight two or more portions of the frequency response. This allows the system parameters to be continuously monitored and analysed. These shift keyed signals are applied to different systems where an MIP or frequency information may be obtained.