Analysis of Acoustic Signatures from Moving Vehicles UsingTime-Varying Autoregressive Models

  • Authors:
  • Kie B. Eom

  • Affiliations:
  • Department of Electrical Engineering and Computer Science, The George Washington University, Washington, DC 20052

  • Venue:
  • Multidimensional Systems and Signal Processing
  • Year:
  • 1999

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Abstract

Time-varyingautoregressive (TVAR) modeling approach for the analysis of acousticsignatures from moving vehicles is presented in this paper. Acousticsignatures from moving vehicles are nonstationary, and featuresextracted under the stationary assumption often result unsatisfactoryperformance. In TVAR modeling approach, the time-varying parametersare expanded as a linear combination of deterministic time functions.In this paper, the TVAR parameters are expanded by a low-orderdiscrete cosine transform (DCT), since DCT is known to be closeto the optimal Kahrunen-Loève transform when the signalis Markov. The maximum likelihood estimation and order selectionin TVAR models are also discussed. Many attributes of vehicleactivities, such as vehicle type, engine speed, loading, roadcondition, etc., may be inferred from the estimated model parameters.The performance of the TVAR modeling approach is tested withboth synthetic and real acoustic signatures. A synthetic signalcontaining multiple time-varying sinusoids are used to comparethe performances in the estimation of time-frequency distributionwith other approaches. In the experiment with acoustic signaturesfrom moving vehicles, it is shown that the TVAR models can beeffectively used to determine vehicle activities and types atclose range and cruising speed.