Claude Jauffret

A new tracker for multiple frequency line

The acoustic surveillance by a passive sonar is the topic of that paper. We propose an automatic detection and tracking procedure of several frequency lines present in a frequency-time representation (called lofargram). Each frequency line being modeled as a first order Markov chain, we adapt a classic algorithm (Forward-Backward) in the literature of the Hidden Markov Models (HMM) to satisfy that need.

Observability: range-only vs. bearings-only target motion analysis for a leg-by-leg observer's trajectory

The aim of so-called range-only target motion analysis (ROTMA) is to estimate the trajectory of a target by a single platform collecting range-only measurements.We focus on the observability analysis when the target is in constant-velocity (CV) motion. More precisely, the observability conditions are established when the observers trajectory is composed of one or several legs. We establish a link between the Fisher information matrix (FIM) and the observability, after having proven the similarity of this matrix with the FIM encountered in bearings-only target motion analysis (BOTMA). We compare observability statuses in BOTMA and ROTMA in the paper.

IMM-UGHF-NJ for continuous wave bistatic sonar tracking with propagation delay

Acoustic propagation delay has not been investigated for a continuous wave multistatic sonar tracking system except for the recent study conducted by Jauffret et al. [4], which estimates the trajectory of a constant velocity target. The results showed that the estimate bias caused by the propagation delay is not negligible, especially for a bistatic system. This paper develops an interacting multiple model unscented Gauss-Helmert filter with numerical Jacobian (IMM-UGHF-NJ) to track a maneuvering target with propagation delay using a bistatic sonar system. The IMM-UGHF-NJ can overcome the two tracking challenges introduced by the delay, namely, implicit state transition model and lack of analytical expression of the Doppler shifted frequency in the measurement model. Simulation tests have been conducted, and the results show that the IMM-UGHF-NJ can reduce the estimation error significantly, especially for fast moving targets.