{"approval":{"approved":true,"approved_at":"2026-10-06T18:41:38Z","approved_by":"Project owner","review_note":"Owner approved the exact 421 MHz Field Note and explicitly requested publication and synchronization through the reviewed handoff. Field Notes only; no Scientific Ledger or historical changes."},"author":"OpenAI Codex","authorship_note":"Assistant-written reporting of assistant-operated, owner-authorized observations. The project owner reviewed and approved this Field Note. Source draft SHA-256: 296402696d4b113a63084d2af83ba6649b232f4b2b13727fc5518a44b485f1ea. Only the approved public-presentation edits were applied; the substantive wording is unchanged.","canonical_url":"https://thegodnet.work/field-notes/a-421-mhz-feature-survives-a-shifted-sweep-grid/","content_sha256":"bfaf9bb4dba7ada500b6e97b5f45cd348945edfa8c090fbe4cdf26ce994e3810","created_at":"2026-10-06T18:41:38Z","epistemic_labels":["observation","analysis","project_status"],"evidence_ids":[],"id":"FN-2026-10-06-013","limitations":[],"publication_type":"field_note","published_at":"2026-10-06T18:41:38Z","related_entries":[],"revision":1,"revision_note":"Initial owner-approved publication.","schema":"tgn.publication.v1","sections":[{"citation_ids":[],"heading":"Observation","items":[],"label":"observation","paragraphs":["The feature near 421 MHz met the predeclared fixed-frequency persistence rule. It appeared above the same +8 dB threshold in both original-grid snapshots. In the shifted scan, the fixed-frequency window reached 11.765 dB above that scan’s median, while the window predicted for a feature following the grid reached 0.945 dB. The fixed-frequency peak was within one nominal bin of the bracketing peak location.","The 457.9 MHz candidate was inconclusive: it did not meet the required threshold in either bracketing original-grid snapshot. That result cannot establish absence."]},{"citation_ids":[],"heading":"Limits of this control","items":[],"label":"analysis","paragraphs":["This single control weakens a simple explanation in which the 421 MHz feature translates with the sweep grid. It does not prove an external transmission, identify an emitter, or distinguish every receiver or local-interference mechanism. The approximately 98 kHz bins limit frequency detail, and powers and antenna response remain uncalibrated. These are sparse exploratory observations, not a scientifically qualified occupancy or calibrated-power campaign."]},{"citation_ids":[],"heading":"Acquisition boundary","items":[],"label":"project_status","paragraphs":["All three calls passed the frozen geometry and diagnostic checks. Acquisition stopped after the three authorized calls. No decoding, retained IQ, transmission or NESDR testing occurred."]}],"slug":"a-421-mhz-feature-survives-a-shifted-sweep-grid","source_draft_sha256":"296402696d4b113a63084d2af83ba6649b232f4b2b13727fc5518a44b485f1ea","sources":[],"status":"active","summary":"On 6 October 2026, an exploratory HackRF survey found recurring narrow-bin energy near 421.1 MHz and 457.9 MHz. A separate, prospectively frozen three-sweep control then used 420–460, 419–459 and 420–460 MHz on the unchanged antenna path and fixed gains.","title":"A 421 MHz feature survives a shifted sweep grid"}