Synchronized Clocks in Electronic Access Systems
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Solution Overview
Problem
Electronic access systems for secured rooms or containers face challenges in reliably logging access events chronologically and securely storing time-stamped data, especially in self-sufficient configurations that lack a permanent interface to a control system, making it difficult to prove authorized or unauthorized access in case of breaches.
Innovation Solution
The system incorporates both an external and a control unit with synchronized clocks and memories to store time-stamped access data, ensuring secure and synchronized time information, and uses a microprocessor for clock generation without a separate real-time clock, with encryption and pairing for enhanced security, allowing for redundant data storage and plausibility checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the access system is made self-sufficient without a permanent interface to a control system, then security against external attacks is improved, but the ability to reliably log and record access events chronologically deteriorates
Solution Approach 1:
The system is divided into two separate units: an outdoor unit that captures user IDs and logs access events locally, and an indoor control unit that provides secure time synchronization and additional logging. This segmentation allows the outdoor unit to maintain security independence while the indoor unit ensures reliable chronological recording through synchronized timestamps.
Solution Approach 2:
A wireless time synchronization mechanism acts as an intermediary between the outdoor and indoor units. The indoor unit transmits time information wirelessly to the outdoor unit, enabling the outdoor unit to stamp logged events with accurate chronological timestamps without requiring a permanent physical interface, thus maintaining both security and logging reliability.
2Reliability
If separate memories are provided in both outdoor and control units for redundant data storage, then reliability of access logging is improved, but device complexity increases
Solution Approach 1:
The outdoor and control units are merged into a single integrated access system with coordinated logging functions. Both units maintain memories for redundant storage, but they operate as part of a unified system with synchronized timekeeping, reducing overall complexity compared to completely independent systems while preserving the benefits of redundant logging.
3Measurement precision
If clock generators in both outdoor and control units are synchronized, then plausibility checking of timestamps is improved, but use of energy increases
Solution Approach 1:
Time synchronization between the outdoor and control units is performed periodically rather than continuously. The indoor control unit transmits time information to the outdoor unit at regular intervals, which is sufficient to maintain timestamp accuracy for logging purposes while significantly reducing energy consumption compared to continuous synchronization.
Data Source
Figure 1
Figure 2
Figure 3~4A
AI summary
The present invention relates to an electronic access system comprising at least one outdoor unit (2) and a separate control unit (3), wherein the outdoor unit (2) has an input device (21) and an evaluation logic (23), and the evaluation logic (23) compares a user identifier captured by the input device (21) with at least one reference in order to assess, by comparison, whether the captured user identifier entitles the user to access or not, and the control unit (3) is configured to receive a release signal from the outdoor unit (2) if the captured user identifier entitles the user to access, and in response to this to generate a control signal as a result of which access is granted to a user of the access system (1).According to the invention, it is particularly provided that both the external unit (2) and the control unit (3) have a clock generator (232, 302) and that the clock generators (232, 302) are synchronized with each other to provide a matched internal timestamp for the access system (1).