System and method for characterizing the resonant responses of a plurality of rotating blades in a turbo machine. The system comprises a plurality of controllable fluid jets disposed about a blade row for exciting rotating blades with selectable frequencies of vibration. The sequential excitation of blades at a plurality of narrowly spaced frequencies and the simultaneous sensing of blade responses sufficiently resolves the resonant center frequencies and harmonics thereof in order to detect changes in characteristic blade resonances.
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