BLE Clock Synchronization for Household Time Drift
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Solution Overview
Problem
Existing devices often experience time drift and fail to automatically update for daylight saving time, and methods like WWV/WWVH services and precision time protocols are expensive and not relevant for household applications, leading to inaccuracies in time synchronization across devices.
Innovation Solution
A system and method using a short-wavelength, ultra-high frequency radio communications protocol for synchronizing clocks within a network, where a master device advertises its time to other devices via Bluetooth Low Energy, allowing them to discipline their clocks and maintain accurate time, including adjustments for daylight saving time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PTP or NTP protocols are used to synchronize clocks, then time synchronization accuracy is improved, but device cost and power consumption increase
Solution Approach 1:
The patent uses Bluetooth Low Energy (BLE) advertisements instead of expensive PTP/NTP infrastructure. The master device periodically broadcasts time information via BLE ads, and slave devices periodically synchronize by listening to these ads. This disposable, lightweight approach replaces complex time protocol infrastructure with simple, low-cost BLE communication, achieving sufficient accuracy for household applications without the high power consumption of continuous protocol operation.
Solution Approach 2:
The system implements periodic time synchronization where the master device periodically advertises time information through BLE advertisements, and slave devices periodically wake up to listen for and process these advertisements. This periodic action pattern reduces power consumption compared to continuous synchronization protocols while maintaining acceptable time accuracy for household devices.
2Measurement precision
If WWV/WWVH time services are used for clock synchronization, then time accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent introduces a master device as an intermediary between external time sources (like WWV/WWVH or internet time servers) and slave devices. The master device receives time information from external sources and redistributes it to all slave devices via BLE advertisements. This intermediary approach simplifies slave device complexity while maintaining time accuracy, as slaves only need to listen to local BLE ads rather than implementing complex radio receivers for WWV/WWVH or full NTP clients.
Solution Approach 2:
The patent extracts the complex time reception and processing functionality from individual slave devices and consolidates it into a single master device. Slave devices are simplified to only need basic BLE advertisement listening and clock discipline capabilities, while the master device handles external time source communication and time distribution logic.
3Device complexity
If devices maintain independent clocks without external synchronization, then device simplicity is improved, but time drift and desynchronization increase
Solution Approach 1:
The system implements self-service time synchronization where slave devices autonomously wake up at scheduled intervals, listen for BLE advertisements from the master device, and automatically discipline their clocks based on the received time information. This self-service approach maintains device simplicity while ensuring time synchronization reliability, as each device independently manages its own clock without requiring manual intervention or complex centralized control.
Solution Approach 2:
The patent implements feedback-based clock discipline where slave devices compare their local clock time against the time received in BLE advertisements and automatically adjust their clocks to minimize drift. This feedback mechanism ensures time synchronization reliability by continuously correcting clock deviations while maintaining simple device architecture through automated adjustment algorithms.
Data Source
AI summary
A method for synchronizing time within a local, networked system including a first device and a least one second device. The first device uses a short-wavelength, ultra-high frequency radio communications protocol to advertise a time that is being maintained by a first clock of the first device. The second device uses the received time to discipline a second clock of the second device such that the second clock of the second device is generally synchronized to the first clock of the first device.