Two different metal test frames are excited using the impact-hammer method. The force-input and specific acceleration-output time-histories were recorded, and through frequency-domain, and time-domain structural system identification methods, the systems were identified. Artifacts of the test method and equipment, in the input-output data are highlighted, and their effect upon the identification is diminished through digital signal processing techniques. With some explainable differences, the correspondence between the systems identified in the frequency-domain, the systems identified in the time-domain, and analytical models of the test structures was quite good. Structural system identification, particularly through discrete time-domain methods (due to the digital nature of future implementations), enables the calibration of synthesized finite element models using prototype data, is an excellent means of non-destructive damage evaluation, and is required for active structural control.