| Dual-Frequency RFID Technology |
Introduction: Smart City Infrastructure and Manhole Cover Safety
Municipal engineering is closely related to public safety and daily urban operations. In the ongoing development of smart cities, the intelligent management of municipal infrastructure has become an essential component of urban governance.
With the increasing maturity of radio frequency identification (RFID) technology, its applications have gradually expanded from logistics and manufacturing to public infrastructure management. Based on power supply methods, RFID systems can be classified into active and passive types. Based on operating frequency, they can be divided into low frequency, high frequency, ultra-high frequency, and microwave systems.
This solution combines the long-distance communication capability of active RFID with the low cost and maintenance-free characteristics of passive ultra-high frequency (UHF) RFID, forming a dual-frequency RFID system suitable for large-scale municipal deployment. The system is applied to municipal manhole cover management, enabling scheduled status reporting, abnormal displacement alarms, and optimized inspection routing, effectively reducing safety risks caused by missing or displaced manhole covers.
Overall System Architecture for Municipal Manhole Cover Management
The dual-frequency RFID manhole cover management system consists of two core components:
- RFID perception subsystem
- Backend municipal management platform
RFID Perception Subsystem
The RFID subsystem includes:
- Dual-frequency RFID tags installed on manhole covers
- Integrated active RFID readers deployed in the field
- Handheld UHF RFID terminals for routine inspections
Under normal conditions, the dual-frequency tag periodically transmits a status signal to the integrated reader. The reader aggregates the data and uploads it to the backend server via a wired or wireless network. Management personnel can view the real-time status of all manhole covers through the monitoring platform.
For daily inspections, handheld UHF RFID devices guide staff along predefined inspection routes and allow them to record on-site conditions. When abnormal movement occurs, the tag immediately triggers an alarm signal, which is forwarded to the backend system for real-time analysis and response.
Because active RFID supports long-distance communication, a single reader can manage multiple manhole covers simultaneously, significantly reducing deployment and operational costs.
Dual-Frequency RFID Subsystem Design
Dual-Frequency RFID Tag Design
The tag design integrates:
- Passive UHF RFID, used for manual inspection and information storage
- Active radio frequency communication, used for periodic reporting and abnormal event alerts
The passive component supports data storage for manhole cover identification, category, and management area. The active component supports low-power wireless transmission for scheduled reporting and emergency alerts.
The system adopts an ultra-low-power design strategy. Under normal conditions, the tag remains in deep sleep mode and is activated only during scheduled reporting or abnormal events. This design enables long-term operation exceeding ten years without battery replacement, meeting the durability requirements of municipal infrastructure.
Tag data frames include identification information, timestamps, location codes, category codes, battery status, and verification data to ensure transmission integrity.
Integrated RFID Reader Design
The integrated reader functions as a data concentrator, managing multiple manhole covers within its coverage area. It receives active RFID signals through an omnidirectional antenna and forwards the collected data to the backend system via a network interface.
This architecture enables centralized monitoring and reduces the number of required field devices, improving system scalability and reliability.
UHF RFID Handheld Devices for Manual Inspection
Handheld UHF RFID devices are used for routine inspections and emergency verification. Inspection tasks are downloaded from the backend system to the handheld terminal. Staff follow the predefined route, read the RFID tag on each manhole cover, and record its status.
After completing the inspection, the collected data is uploaded to the backend platform and used for performance evaluation, maintenance planning, and audit records.
Backend Platform Functions and Manhole Cover Positioning
The backend management platform provides the following core functions:
- Data collection and storage
- Abnormal status analysis
- Inspection route planning
- Maintenance record management
An electronic map is integrated into the system, marking the precise location of each manhole cover. When abnormal data is received, the system automatically identifies the responsible area and personnel and sends notification alerts for emergency handling.
The platform also performs daily statistical analysis of reporting data. If a manhole cover fails to report within the expected period, the system locates the asset and initiates an investigation. Battery status trends are analyzed to identify potential device failures in advance.
Based on real-time system data, the platform automatically generates optimal inspection routes and distributes them to handheld terminals, ensuring efficient use of inspection resources.
Conclusion: Applicability in Municipal Engineering Projects
Field stress tests demonstrate that the proposed dual-frequency RFID manhole cover management system is stable, cost-effective, and suitable for large-scale deployment. The tags support long service life, low maintenance requirements, and reliable operation in complex outdoor environments.
The system significantly improves the efficiency of municipal facility management, reduces operational costs, and enhances public safety. Due to its standardized architecture, low deployment threshold, and strong scalability, it is well suited for municipal engineering projects at city, district, and county levels, supporting the long-term development of smart city infrastructure.
