Ieee gold2010 sermi

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Ieee gold2010 sermi

  1. 1. Coordinate Registration of OTHR-SW Remotely-Sensed Data by Sea-Land Transitions Identification Università di Firenze Dipartimento di Elettronica e Telecomunicazioni F. Sermi, F. Cuccoli, L. Facheris, D. Giuli IEEE Gold 2010 29, 30 April 2010 – Naval Academy, Livorno, Italy Consorzio Nazionale Interuniversitario per le Telecomunicazioni (centro RaSS)
  2. 2. OTHR-SW <ul><li>Main feature: </li></ul><ul><li>Huge Surveillance Area (comparable in surface with that of satellite constellations or airborne radar networks ). </li></ul><ul><li>Main Problem: </li></ul><ul><li>Eterogeneous & Unstable nature of the Ionosphere introduces uncertainty in the evaluation of the actual signal path. </li></ul>The coordinate registration (CR) procedure allows to associate digital data to coordinates that determine univocally its position on the Earth surface. Without a correct CR procedure OTHR-SW data are useless. The radar echo needs to be geo-referenciate! 1/8
  3. 3. Remote sensing with HF radars 1/8 The huge surveillance area of OTHR-SW systems and the interaction between EM waves in the HF band and sea swells can be employed to gather environmental data on a very large scale. Since the ‘70s several methods have been proposed to extract sea-state information from the OTHR-SW echo. Like other measurements, environmental data are useless without an appropriate CR.
  4. 4. Typical CR Method 2/8 <ul><li>the updating time is generally longer than the coherence time of the Ionosphere, hence the ionospheric model is generally approximated. </li></ul>Remarks: <ul><li>a dense network of ionosondes (displaced within the surveillance area) is needed to account for the ionospheric heterogeneity; </li></ul>
  5. 5. Proposed CR Method 1/2 3/8 <ul><li>the CR process basically consists in a cross-correlation (hence low computational cost) and can be applied for every echo involving at lest a sea/land transition. </li></ul>Remarks: <ul><li>there is no need for data from sources external to the system; </li></ul>
  6. 6. Proposed CR Method 2/2 4/8 <ul><li>Besides the coastline profiles, other geo-morphological features of the surveillance area could be employed as reference by this method. </li></ul>In other terms… <ul><li>The proposed CR method employs the a priori knowledge of the coastline profiles within the surveillance area in order to geo-referenciate the OTHR-SW received echo; </li></ul><ul><li>The CR process basically consists in the cross-correlation between the received echo and the clutter profile of the surveillance area for the selected azimuthal direction; </li></ul><ul><li>The method can be applied to every echo relative to a radar footprint characterized by at least one sea/land transition; </li></ul><ul><li>Its relatively low computational cost allows the CR process to be directly introduced in the OTHR-SW system radar routine; </li></ul><ul><li>The process could allow to gather real time information about the Ionosphere in order to continuously update an opportunely parametrized ionospheric model. </li></ul>
  7. 7. OTHR-SW Scenario & Parameters 5/8
  8. 8. HF signals and the Ionosphere 6/8 <ul><li>The interaction between HF signals and the Ionosphere depends on the couple [  , f ], (namely incidence angle and frequency). </li></ul><ul><li>In the simulated scenario we supposed to operate with constant frequency and we hypothesized negligible the differences of  within the same 3dB radar beam. </li></ul><ul><li>Nevertheless this effect needs to be taken into account in a real scenario … </li></ul>
  9. 9. Radar Footprint Reconstruction 7/8 Reconstructed radar footprints: A : the Ionosphere is modeled as a perfect reflecting mirror at a given height; B : a locally-homogeneous electron density profile is associated to the Ionosphere . Simulated echoes: The black curve is associated to A , while the red one is associated to B .
  10. 10. Results and Conclusions A simplified OTHR scenario confirms that the sea/land transitions can be profitably used for the real time CR of the OTHR-SW signals . The method is jet to be tested in a scenario that accounts for the dependence of the ionospheric reflection height from the incidence angle of the ray. The developed method is optimal for the application in a complex coastline profiles scenario . 8/8 After the analisys of the surveillance area by the OTHR-SW system, other geomorphological features (beside the coastal profiles) could be employed in the CR method.
  11. 11. Coordinate Registration of OTHR-SW Remotely-Sensed Data by Sea-Land Transitions Identification Università di Firenze Dipartimento di Elettronica e Telecomunicazioni F. Sermi, F. Cuccoli, L. Facheris, D. Giuli IEEE Gold 2010 29, 30 April 2010 – Naval Academy, Livorno, Italy Consorzio Nazionale Interuniversitario per le Telecomunicazioni (centro RaSS)

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