researResearch - Télécom Bretagne
researResearch - Télécom Bretagne
researResearch - Télécom Bretagne
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<strong>researResearch</strong><br />
difficulties tied to the importing of this microwave<br />
technique into a more geophysical context led to<br />
the elaboration of innovative solutions for<br />
maintaining the coherence of the simulations.<br />
Currently, the simulator is operational and in the<br />
test phrase for the simulation of airborne SAR<br />
results (cf. Figure 1).<br />
is not possible without taking into consideration<br />
the spatial diversity of some sensors, such as<br />
multifaceted sounders through the techniques of<br />
goniometry and calibration. A prospective study<br />
is underway with IFREMER on the topic for an<br />
overview. Additionally, a synergy is slowly<br />
starting to develop with Kongsberg Maritime<br />
(world's biggest builder of multifaceted<br />
sounders) with the sabbatical of one of our<br />
permanent employees in their research center in<br />
Norway, and the financing of a thesis on the topic<br />
for September 2009.<br />
Figure 1 : Simulation of radar observation of an ocean surface by combining<br />
a ray launcher with a local and discrete propagation calculation<br />
on a meshed surface<br />
b. « Sonar »<br />
138<br />
1. Interferometry<br />
From the beginning of the IEM anchor project,<br />
the principal approach relative to bathymetry has<br />
been based on the notion of triangulation based<br />
on interferometry and, more generally, on<br />
antenna processing. Our most recent efforts in<br />
this area have mainly to do with techniques that<br />
could make it possible to increase resolution and<br />
precision. Two theses in partnership with<br />
IFREMER demonstrated that it is possible to<br />
create high resolution digital terrain models with<br />
lateral interferometric sonar or multifaceted<br />
sounders. A conference paper was given on this<br />
problem concerning the formalization of a<br />
method dedicated to remove phase 2πambiguities<br />
between received signals (also<br />
called Vernier method) at Océans 2008. The<br />
problem with these digital models is their noise<br />
level. Today, industrial players are focusing on<br />
resolution and precision. Sonar users want more<br />
and more a highly multi-purpose system that<br />
makes it possible to do bathymetry, image and<br />
high-resolution bathymetry on obstructions. This<br />
High resolution bathymetry computed from data collected over the ERIKA<br />
wreck.
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