2025_programme: Orthogonal Waveform Design for MIMO Synthetic Aperture Sonar

• Day: June 20, Friday
    Location / Time: B. ERATO at 08:50 - 09:10
• Last minutes changes: -
• Session: 30. Underwater Sensors Technology
  Organiser(s): N/A
  Chairperson(s): Yannik Steiniger
• Lecture: Orthogonal Waveform Design for MIMO Synthetic Aperture Sonar
  Paper ID: 2306
  Author(s): David Holmgren, Per Abrahamsson, Louise Fuchs, Andreas Gällström
  Presenter: David Holmgren
  Abstract: Synthetic aperture sonar (SAS) combines successively transmitted signals along a known track to increase along-track resolution. In order to fulfill the along-track sampling requirements, the receiver array typically moves half the total array length between pings, limiting the area coverage rate. In order to increase the area coverage rate without increasing the physical size of the receiver array, MIMO SAS has been suggested [1]. By transmitting different sonar pulses at the same time, it is theorized that MIMO SAS can double the area coverage rate. The key problem with implementing MIMO SAS is that the receiver needs to efficiently distinguish between the emitted pulses to avoid introducing artifacts in the final SAS image. By using so-called orthogonal waveforms, it could be possible to separate transmitted waveforms by a matched filter even if they utilize the same frequency band [2]. \n\nOrthogonal waveforms were evaluated based on their auto- and cross-correlation properties and ambiguity surface characteristics. The produced waveforms were implemented in a SAS simulator, evaluating the implications of using orthogonal waveforms in different acoustic environments. It was shown that the utilization of orthogonal waveforms can increase the coverage rate of SAS systems, but as two waveforms sharing the same frequency bands are never completely orthogonal, leakage occurred. When multi-target simulations were performed, it was shown that the leakage significantly affected the final image quality. To potentially reduce leakage, an alternative receiver design based on the least squares method was suggested.\n \n[1] Roy Edgar Hansen. “MIMO synthetic aperture sonar: Benefits and limitations”. In: Electronics Letters 59.2 (2023), e12723. \n[2] Antoine Blachet et al. “Multibeam Echosounder With Orthogonal Waveforms: Feasibility and Potential Benefits”. In: IEEE Journal of Oceanic Engineering 46.3 (2021), pp. 963–978\n
• Corresponding author: Mr David Holmgren
  Affiliation: Saab AB
  Country: Sweden