Real-time, 45 MHz, split-aperture phased array beamformer with efficient sign coherence grating lobe suppression
Why this work is in the frame
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Bibliographic record
Abstract
A digital variable sampling high-frequency beamformer implementing real-time grating lobe suppression is described. The system is tested using a semi-kerfed 64 element 45 MHz phased array with 1λ element pitch. The grating lobe suppression is facilitated with the sign coherence factor (SCF) and split-aperture transmit beamforming techniques. A new split-aperture transmit technique called “sub-aperture probing” (SAP) is described, experimentally validated, and compared to previously developed split-aperture techniques with respect to grating lobe suppression. Grating lobe levels were suppressed to be 49 and 60 dB below the main lobe when using 2 split-apertures with a SCF weighting factor of 1 and 2. These levels were further suppressed to 51 and 66 dB below the main lobe when splitting the aperture into 4 evenly sized apertures. When using SAP with 16 elements for the sub-aperture, grating lobes were suppressed to 49 and 64 dB below the main lobe. SAP with 8 elements yielded improved results compared to SAP with 16 elements; suppressing grating lobe levels to 49 and 65 dB below the main lobe for the associated SCF weighting coefficients. Finally the grating lobe suppression performance was tested on a wire target embedded in a tissue phantom and the signal to tissue speckle levels were characterized.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it