--- title: "Empirical BLE-trained holdover — PToB research" description: "W12 frozen-clock experiments: a 64 s sampled device frontier and a separate 75 s fixed-cohort result, with later 24 s windows, failures and observation gaps retained." url: "https://ptob.dev/research/empirical-ble-holdover/" language: "en" robots: "index, follow, max-image-preview:large, max-snippet:-1, max-video-preview:-1" representations: {"application/json":"https://ptob.dev/research/empirical-ble-holdover/?format=json","text/markdown":"https://ptob.dev/research/empirical-ble-holdover/?format=markdown"} format_description: "https://ptob.dev/agent-formats.json" --- # Empirical Sub-Microsecond Holdover on BLE-Trained Software Clocks Approved research draft 30 October 2026 7 pages · PDF How long can a frozen BLE-trained software clock retain sampled sub-microsecond P99 error? [Read PDF](https://ptob.dev/papers/preview/?file=%2Fpapers%2Fptob-empirical-sub-microsecond-holdover-20261030.pdf)[Cite this edition](https://ptob.dev/research/empirical-ble-holdover/#citation) ## Overview This MCXO-inspired W12 study freezes a software clock model and evaluates its worst sampled error in each run prefix against later authenticated BLE witnesses. The longest fully replayed rolling device frontier reaches 64 seconds across 128 prefixes, with P99 760 ns and maximum 879 ns. ## What this paper covers - Distinguish a rolling device frontier from a fixed mature cohort and a final capture-end window. - Read P99 across per-run worst sampled errors with failures, unknowns, censoring and witness gaps retained. - Reproduce the numeric prefixes from compact public evidence without accessing hardware. ## Research scope A separate fixed mature 128-run cohort passes 75 seconds at P99 983 ns and fails at 76 seconds. Later rolling capture-end windows fall to 24 seconds. These populations are not interchangeable. Temperature is shadow-only; sampled BLE-relative error does not establish continuous accuracy, calibrated UTC, physical output or GM-transition acceptance. ## Read it in context The approved seven-page draft measures W12 v0.2.33. Its schematic audits v0.2.34 separately. CoreSE has its own shadow instrument and a separate ≥1.75-second sampled result; W12’s duration cannot be transferred to that target. [Inspect the dated holdover results](https://ptob.dev/research/#w12-holdover)[Source, compact evidence and offline replay](https://github.com/yantisj2/PToB/tree/main/papers/mcxo-holdover-duration)[Explore the CoreSE instrument](https://ptob.dev/hardware/#corese) ## Cite this edition Jonathan Yantis. Empirical Sub-Microsecond Holdover on BLE-Trained Software Clocks. 30 October 2026. Approved research draft. [Original PDF](https://ptob.dev/papers/preview/?file=%2Fpapers%2Fptob-empirical-sub-microsecond-holdover-20261030.pdf). Summary permalink: [https://ptob.dev/research/empirical-ble-holdover/](https://ptob.dev/research/empirical-ble-holdover/) Jonathan Yantis leads protocol design, hardware development and research. GPT 6.1 contributes implementation, analysis and documentation. This page summarizes the linked edition; retain its original evidence dates and measurement references. ## The full paper The original document includes the technical detail and references behind this summary. [Read PDF](https://ptob.dev/papers/preview/?file=%2Fpapers%2Fptob-empirical-sub-microsecond-holdover-20261030.pdf) [Cite this edition](https://ptob.dev/research/empirical-ble-holdover/#citation) [Paper sources on GitHub](https://github.com/yantisj2/PToB/blob/main/papers/README.md) ## Continue exploring [Affordable timing from Starlink over WiFi](https://ptob.dev/research/starlink-wifi-timing/)[Trustworthy timing in Zephyr](https://ptob.dev/research/zephyr-hardware-timestamps/)[Low-level timing on ESP32-S3](https://ptob.dev/research/esp32-s3-event-capture/)[BLE timing tails and multipath](https://ptob.dev/research/ble-timing-tails-multipath/)[From BLE to a Pi NTP/PTP gateway](https://ptob.dev/research/pi5-mhat-time-gateway/)[From USB frames to a macOS clock](https://ptob.dev/research/usb-macos-time-transfer/)[ESP32-S3 causal clock discipline](https://ptob.dev/research/esp32-s3-causal-clock-discipline/)[Timing information and power scheduling](https://ptob.dev/research/awake-timing-power-scheduling/)[All research & evidence](https://ptob.dev/research/) ## Structured data ```json { "@context": "https://schema.org", "@graph": [ { "@type": "WebSite", "@id": "https://ptob.dev/#website", "url": "https://ptob.dev/", "name": "PToB", "alternateName": [ "Precision Time over BLE", "Precision Time over Bluetooth" ], "description": "Bluetooth and USB software clocks: W12 60.3 ns relative-PPS RMS over 522/600 observations, separate 64 s sampled holdover, and CoreSE diagnostics.", "inLanguage": [ "en", "de" ], "publisher": { "@id": "https://ptob.dev/#jonathan-yantis" } }, { "@type": "Person", "@id": "https://ptob.dev/#jonathan-yantis", "name": "Jonathan Yantis", "url": "https://github.com/yantisj2/PToB/blob/main/CREDITS.md" }, { "@type": "Project", "@id": "https://ptob.dev/#project", "name": "PToB", "alternateName": "Precision Time over BLE", "url": "https://ptob.dev/", "description": "An independent protocol project researching precision time transfer across Bluetooth-enabled microcontrollers and USB clients.", "sameAs": "https://github.com/yantisj2/PToB", "member": { "@id": "https://ptob.dev/#jonathan-yantis" }, "knowsAbout": { "@id": "https://ptob.dev/#protocol" } }, { "@type": "Thing", "@id": "https://ptob.dev/#protocol", "name": "Precision Time over BLE", "alternateName": "PToB", "description": "An experimental PTP-inspired protocol proposal for wireless clock synchronization over Bluetooth Low Energy." }, { "@type": "WebPage", "@id": "https://ptob.dev/research/empirical-ble-holdover/#webpage", "url": "https://ptob.dev/research/empirical-ble-holdover/", "name": "Empirical BLE-trained holdover — PToB research", "description": "W12 frozen-clock experiments: a 64 s sampled device frontier and a separate 75 s fixed-cohort result, with later 24 s windows, failures and observation gaps retained.", "inLanguage": "en", "keywords": [ "Bluetooth clock synchronization", "Precision Time over BLE", "Implementation & time transfer" ], "isPartOf": { "@id": "https://ptob.dev/#website" }, "author": { "@id": "https://ptob.dev/#jonathan-yantis" }, "about": { "@id": "https://ptob.dev/#protocol" }, "dateModified": "2026-10-30", "image": "https://ptob.dev/social/ptob-timing-v3.jpg", "breadcrumb": { "@id": "https://ptob.dev/research/empirical-ble-holdover/#breadcrumbs" }, "mainEntity": { "@id": "https://ptob.dev/papers/ptob-empirical-sub-microsecond-holdover-20261030.pdf#article" } }, { "@type": "BreadcrumbList", "@id": "https://ptob.dev/research/empirical-ble-holdover/#breadcrumbs", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "PToB", "item": "https://ptob.dev/" }, { "@type": "ListItem", "position": 2, "name": "Bluetooth and Starlink timing research and results", "item": "https://ptob.dev/research/" }, { "@type": "ListItem", "position": 3, "name": "Empirical BLE-trained holdover", "item": "https://ptob.dev/research/empirical-ble-holdover/" } ] }, { "@type": "ScholarlyArticle", "@id": "https://ptob.dev/papers/ptob-empirical-sub-microsecond-holdover-20261030.pdf#article", "url": "https://ptob.dev/research/empirical-ble-holdover/", "headline": "Empirical Sub-Microsecond Holdover on BLE-Trained Software Clocks", "name": "Empirical Sub-Microsecond Holdover on BLE-Trained Software Clocks", "description": "W12 frozen-clock experiments: a 64 s sampled device frontier and a separate 75 s fixed-cohort result, with later 24 s windows, failures and observation gaps retained.", "author": { "@id": "https://ptob.dev/#jonathan-yantis" }, "datePublished": "2026-10-30", "dateModified": "2026-10-30", "inLanguage": "en", "creativeWorkStatus": "Approved research draft", "about": { "@id": "https://ptob.dev/#protocol" }, "mainEntityOfPage": { "@id": "https://ptob.dev/research/empirical-ble-holdover/#webpage" }, "image": "https://ptob.dev/social/ptob-timing-v3.jpg", "encoding": { "@type": "MediaObject", "contentUrl": "https://ptob.dev/papers/ptob-empirical-sub-microsecond-holdover-20261030.pdf", "encodingFormat": "application/pdf" }, "isPartOf": { "@id": "https://ptob.dev/research/#webpage" } } ] } ```