The digital control of swept sine-wave tests and the associated theory needed for swept sine-wave synthesis and analysis will be discussed. This type of testing requires that the digital vibration control system drive the actuator subsystem with an analog signal. This signal is a low-distortion sine wave with a smoothly varying frequency and amplitude. The testing also requires that the controller be able to measure the response of this type of excitation by way of a control transducer mounted at some chosen point on the device under test. This paper will concentrate on the details of output signal generation to enhance its accuracy and suitability for complex heterodyne generation. The complex heterodyne is used in conjunction with 0-Hz intermediate frequency detectors to implement a digital tracking filter. Digital low-pass filters are used to implement 0-Hz intermediate frequency detectors. The tracking filter is used for time-variable spectral analysis6 (i.e., determining the instantaneous complex amplitude of a sweeping sine wave as encounted in swept sine testing).

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