The Fessenden Oscillator: The first sonar transducer
Bibliographic record
Abstract
When the RMS Titanic sunk in 1912, there was a call placed forth by ship owners for inventors to offer solutions for ship collision avoidance methods. Canadian born inventor Reginald A. Fessenden answered this call while working at the former Boston Submarine Signal Company with the invention and development of the first modern transducer used in a sonar. The Fessenden oscillator was an edge clamped circular metal with a radiating head facing the water on one side while the interior side had a copper tube attached that moved in and out of a fixed magnetic coil. The coil consisted of a direct-current (DC) winding to provide a magnetic field polarization and an alternating-current (AC) coil winding to induce the current into the copper tube and thus translate the magnetic field polarization to the radiating plate with vibrations that translated from the radiating head to the water medium. The prototype and early model versions operated at 540 Hz. Later developments included adaptation of this same transducer for use in underwater communications, obstacle avoidance with WW I retrofits onto British submarines for both transmitting and receiving applications including mine detection. This presentation will discuss design details including a modern numerical modelling effort.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.004 |
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".