Broad-band, large delay range, high precision, and variable analog delay lines for a high-frequency phased array beamformer
Bibliographic record
Abstract
A set of prototype RF delay lines have been developed in order to meet the required bandwidth, delay accuracy, and delay range requirements for a previously developed 64 channel endoscopic phased array prototype. Each delay line is based on a planar PMN-32%PT pulse-echo transducer situated in a water bath, reflecting off a polished brass reflector. The pulse-echo transducers are mounted on individual in-house fabricated piezoelectric bimorphs, which are ‘simply’ supported. This creates an electronic delay time proportional to the distance between the single-element transducer and the reflecting surface in the water bath. When the physical length between the transducer and the reflecting surface is changed, the delay time also changes. A variable high voltage signal causes bimorph actuation and, in turn, the variable delays. The experimentally measured centre frequency and bandwidth for the pulse echo transducers was 45 MHz and 60% respectively. The pulse echo insertion loss without considering water attenuation or loss into the brass reflector was measured to be −20.8 dB, therefore one single low-noise amplifier with 20 dB gain was required for each delay line to have zero insertion loss. The signal-to-noise ratio was only decreased by 1.1dB with this amplifier in place. The total delay range measured by adjusting the bimorph voltage by +/− 80V was 1.4 µs, and the accuracy/repeatability of the pulse delay was less than 3ns. To date 16 channels of individually controlled parallel delays have been fabricated and the fabrication/testing of a full 64 channel system is ongoing.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".