Designing multifrequency adaptive digital signals using symbolic addition

Multifrequency testing by a microcomputer uses discrete interval periodic multifrequency test signals to interrogate a system with the aim of system identification in a non-parametric frequency response form. It involves one multifrequent experiment which combines the traditional monofrequent experiments. Data measurement, which is the precision measurement analogy of data communication, allows identification coding theorems and symbolic operations to be successfully applied in the design of a variety of data measurement signals. The three main symbolic operations are symbolic coding, symbolic phase shift keying and symbolic addition. In certain kinds of experiments the most suitable multifrequency test signal should be adapted so that the signal-to-noise-power-ratio at the output is the same for each test frequency. Commonly the noise at the system output has a uniform power spectral density. This paper examines the use of weighted symbolic addition of square waves in the design of multifrequency adaptive digital test signals for this situation. These precision test signals have complementary multisymbol codes determined by the DAC output levels