New real-time algorithms for arbitrary, high precision function generation with applications to acoustic transducer excitation

A system is described for the design, downloading and execution of arbitrary functions, intended for use with acoustic and low-frequency ultrasonic transducers in condition monitoring and materials testing applications. The instrumentation comprises a software design tool and a powerful real-time digital signal processor unit, operating at 580 million multiplication-accumulations per second (MMACs). The embedded firmware employs both an established look-up table approach and a new function interpolation technique to generate the real-time signals with very high precision and flexibility. Using total harmonic distortion (THD) analysis, the purity of the waveforms have been compared with those generated using traditional analogue function generators; this analysis has confirmed that the new instrument has a consistently superior signal-to-noise ratio.