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Compression for Synthetic Aperture Sonar Signals

Compression for Synthetic Aperture Sonar Signals. Thomas Higdon MDDSP May 1, 2008. What is synthetic aperture processing?. Collect sensor data at a series of physical locations. Aggregate the data and process it to form an image. Typical SAS Image. Edge detection Speckle noise reduction.

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Compression for Synthetic Aperture Sonar Signals

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  1. Compression for Synthetic Aperture Sonar Signals Thomas Higdon MDDSP May 1, 2008

  2. What is synthetic aperture processing? • Collect sensor data at a series of physical locations. • Aggregate the data and process it to form an image.

  3. Typical SAS Image • Edge detection • Speckle noise reduction

  4. Why compression is needed • Data for a typical sonar array might arrive at many megabytes/sec. • Storage on autonomous vehicles is limited. • Compression might allow data to be reasonably transmitted via underwater communication links.

  5. SPIHT [Said, Pearlman,. 1996] • Wavelet transform-based • Transmits wavelet coefficients with more information first. • Capable of very low bit rates by recording only decisions made by the encoder. • Capable of arbitrary bit rates.

  6. Basic SPIHT Algorithm • ci,j – wavelet coefficients • μn – number of coefficients in the range

  7. Spatial Orientation Tree • Each pixel has four descendants. • SPIHT uses each pixel’s descendants to decide if a pixel is significant.

  8. Wavelet Packet Transform • Each subband is divided further, based on some metric.

  9. Wavelet Packet Transform • The irregular tree structure makes the spatial orientation tree more complex than in traditional SPIHT.

  10. 0.1 bpp, 80:1 compression

  11. JPEG @ 0.1 bpp

  12. .025 bpp 320:1 compression

  13. .015 bpp, 533:1 compression

  14. 0.05 bpp, 160:1 compression

  15. 0.01 bpp 800:1 compression

  16. PSNR

  17. WSNR

  18. UQI

  19. Questions

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