fastphenotrack vision processing  (SRI International)

Journal: IEEE transactions on ultrasonics, ferroelectrics, and frequency control

Article Title: Correction for Hydrophone Spatial Averaging Artifacts for Circular Sources

doi: 10.1109/TUFFC.2020.3007808

Figure Lengend Snippet: Simulated waveforms at four different levels of local distortion parameter, σq, before (left column) and after (right column) accounting for spatial averaging effects due to reception by a membrane hydrophone with a geometrical sensitive element diameter of 500 μm (by application of the SAF). The source has a center frequency of 5 mHz, diameter of 19 mm, and a focal length of 38 mm. The nonlinearity index values were σq = 0.6, σm = 0.5, SI = 0.06 (top row), σq = 1.0, σm = 0.8, SI = 0.11 (second row), σq = 2.3, σm = 1.9, SI = 0.32 (third row), and σq = 4.6, σm = 3.9, SI = 0.45 (fourth row).

Article Snippet: Inverse filtering with the SAF (“Decon Sens + SAF”) significantly suppresses spatial averaging effects. shows that measurements made with the high-resolution HGL-0085 hydrophone ( d g = 85 μ m) that were not corrected for spatial averaging (“Raw RF” or “Decon Sens”) were consistent with the trends of measurements made with the membrane hydrophones that were corrected for spatial averaging (“Decon Sens + SAF”).

Techniques: Membrane

Journal: IEEE transactions on ultrasonics, ferroelectrics, and frequency control

Article Title: Correction for Hydrophone Spatial Averaging Artifacts for Circular Sources

doi: 10.1109/TUFFC.2020.3007808

Figure Lengend Snippet: Effects of spatial averaging on measurements of peak compressional pressure (pc), peak rarefactional pressure (pr), and pulse intensity integral for the 25 transducer/hydrophone combinations. The plots show: 1) raw data (“Raw RF”); 2) data deconvolved for hydrophone sensitivity only (“Decon Sens”); and 3) data deconvolved for hydrophone sensitivity and inverse filtered using Sp(nf1) over all harmonics with sufficient SNR (see Fig. 8) (“Decons Sens + SAF”). Data are plotted as a function of hydrophone nominal geometric sensitive element diameter, dg. Error bars (which are so small they are difficult to discern) denote standard deviations. Linear and exponential fits to data are also shown.

Article Snippet: Inverse filtering with the SAF (“Decon Sens + SAF”) significantly suppresses spatial averaging effects. shows that measurements made with the high-resolution HGL-0085 hydrophone ( d g = 85 μ m) that were not corrected for spatial averaging (“Raw RF” or “Decon Sens”) were consistent with the trends of measurements made with the membrane hydrophones that were corrected for spatial averaging (“Decon Sens + SAF”).

Techniques:

Journal: IEEE transactions on ultrasonics, ferroelectrics, and frequency control

Article Title: Correction for Hydrophone Spatial Averaging Artifacts for Circular Sources

doi: 10.1109/TUFFC.2020.3007808

Figure Lengend Snippet: Membrane hydrophone simulation results (open circles and squares) for percent error in estimates of peak compressional pressure (pc), peak rarefactional pressure (pr), and pulse intensity integral, when: 1) no spatial averaging correction is applied (“Without SAF”) and 2) the full SAF inverse filter correction is applied (“With SAF”). Measurements are shown in asterisks and x’s. All simulation and experimental data were inverse filtered to deconvolve the effects of hydrophone frequency-dependent sensitivity. Simulation data without SAF are fit to functions of the form – 100% × [1 − exp(−αx)], where x = dg/(λ1F#) and α is a fitting parameter. Standard deviations for measurements are less than 1%.

Article Snippet: Inverse filtering with the SAF (“Decon Sens + SAF”) significantly suppresses spatial averaging effects. shows that measurements made with the high-resolution HGL-0085 hydrophone ( d g = 85 μ m) that were not corrected for spatial averaging (“Raw RF” or “Decon Sens”) were consistent with the trends of measurements made with the membrane hydrophones that were corrected for spatial averaging (“Decon Sens + SAF”).

Techniques: Membrane

Journal: IEEE transactions on ultrasonics, ferroelectrics, and frequency control

Article Title: Correction for Hydrophone Spatial Averaging Artifacts for Circular Sources

doi: 10.1109/TUFFC.2020.3007808

Figure Lengend Snippet: Needle/fiber optic hydrophone simulation results (open circles and squares) for percent error in estimates of peak compressional pressure (pc), peak rarefactional pressure (pr), and pulse intensity integral, when: 1) no spatial averaging correction is applied (“Without SAF”) and 2) the full SAF inverse filter correction is applied (“With SAF”). All simulation data were inverse filtered to deconvolve the effects of hydrophone frequency-dependent sensitivity. Simulation data without SAF are fit to functions of the form −100% × [1 − exp(−βx2)], where x = dg/(λ1F#) and β is a fitting parameter.

Article Snippet: Inverse filtering with the SAF (“Decon Sens + SAF”) significantly suppresses spatial averaging effects. shows that measurements made with the high-resolution HGL-0085 hydrophone ( d g = 85 μ m) that were not corrected for spatial averaging (“Raw RF” or “Decon Sens”) were consistent with the trends of measurements made with the membrane hydrophones that were corrected for spatial averaging (“Decon Sens + SAF”).

Techniques: