Subspace system identification framework for the analysis of multimoded propagation of THz-transient signals

Galvao, R. K. H., Hadjiloucas, S. ORCID: https://orcid.org/0000-0003-2380-6114, Becerra, V. M. and Bowen, J. W. (2005) Subspace system identification framework for the analysis of multimoded propagation of THz-transient signals. Measurement Science & Technology, 16 (5). pp. 1037-1053. ISSN 0957-0233 doi: 10.1088/0957-0233/16/5/001

Abstract/Summary

We provide a system identification framework for the analysis of THz-transient data. The subspace identification algorithm for both deterministic and stochastic systems is used to model the time-domain responses of structures under broadband excitation. Structures with additional time delays can be modelled within the state-space framework using additional state variables. We compare the numerical stability of the commonly used least-squares ARX models to that of the subspace N4SID algorithm by using examples of fourth-order and eighth-order systems under pulse and chirp excitation conditions. These models correspond to structures having two and four modes simultaneously propagating respectively. We show that chirp excitation combined with the subspace identification algorithm can provide a better identification of the underlying mode dynamics than the ARX model does as the complexity of the system increases. The use of an identified state-space model for mode demixing, upon transformation to a decoupled realization form is illustrated. Applications of state-space models and the N4SID algorithm to THz transient spectroscopy as well as to optical systems are highlighted.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/15226
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Department of Bio-Engineering
Uncontrolled Keywords	ultrafast measurements, spectroscopy, far infrared, spectral, discrimination, PROGRAMMABLE DISPERSIVE FILTER, FEMTOSECOND OPTICAL PULSES, FREQUENCY-RESPONSE DATA, FIBER BRAGG GRATINGS, WAVE-FORM GENERATION, STATE-SPACE MODELS, TERAHERTZ PULSES, LASER-PULSES, SPECTRAL, INTERFEROMETRY, CHIRP COMPENSATION
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