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In scenarios such as industrial automation, smart medical care, and logistics warehousing, real-time positioning systems (RTLS) have become a key tool for improving operational efficiency. Its core component, the positioning tag, uses different technical principles to achieve precise tracking from centimeter level to regional level, supporting diverse needs from equipment management to personnel safety.
UWB ultra-wideband tag: "spatial ruler" for high-precision positioning
UWB tags transmit nanosecond narrow pulse signals and use two-way time of flight (TW-TOF) or time difference of arrival (TDOA) algorithms to achieve positioning. Its core advantages lie in sub-meter accuracy and strong anti-interference capabilities. In complex electromagnetic environments, UWB signals can penetrate metal obstacles and resist multipath effects to ensure positioning stability. On the technical level, UWB tags need to cooperate with anchor base stations to calculate three-dimensional coordinates by measuring the signal flight time, with an accuracy of 10-30 cm, which is suitable for high-precision scenarios such as surgical instrument tracking and AGV navigation. Its power consumption is high, but it can achieve 1-3 years of battery life through low-power design, becoming the preferred solution in Industry 4.0 scenarios.
BLE low-power Bluetooth tag: a cost-effective "smart button"
Based on the Bluetooth 5.0/5.1 protocol, BLE tags achieve positioning through received signal strength indication (RSSI) or angle of arrival (AOA) algorithms. Its core value lies in low cost and easy deployment. The price of a single tag is only 1/5 of that of UWB, and it can reuse existing Wi-Fi infrastructure and achieve rapid networking through Bluetooth gateways. Technically, BLE tags use the 2.4GHz frequency band to transmit data. The positioning accuracy is greatly affected by environmental interference and is usually 1-3 meters, but it can be improved to 0.5 meters through the AOA algorithm. Its IP67 protection level and 12-18 months of battery life make it an ideal choice for large-scale deployment scenarios such as retail shelf management and asset inventory.
RFID active tags: long-lasting "invisible guards"
RFID active tags have built-in batteries, actively transmit radio frequency signals, and achieve positioning by measuring signal arrival time difference (TDOA) or area coverage. Its core advantages lie in its ultra-long battery life and multi-tag concurrent reading capability. A single tag can last for more than 5 years and can read hundreds of tags per second. Technically, RFID active tags operate in the 860-960MHz or 2.4GHz frequency bands. The positioning accuracy is affected by the tag density and reader layout, usually 3-5 meters, but can be increased to 1 meter by densely deploying readers. In scenarios such as animal husbandry ear tags and library book management, RFID active tags have become the first choice for long-term tracking with their "zero maintenance" characteristics.
Wi-Fi tags: an "economical choice" for infrastructure reuse
Wi-Fi tags use existing wireless network infrastructure to achieve positioning by measuring signal transmission time (TOA) or strength (RSSI). Its core value lies in zero additional hardware investment. Enterprises only need to enable the positioning function in the AP to upgrade the existing Wi-Fi network to a positioning system. Technically, Wi-Fi tags support the IEEE 802.11mc standard and achieve a positioning accuracy of 1-2 meters through the fine timing measurement (FTM) protocol, but are greatly affected by interference in the 2.4GHz frequency band. In scenarios such as shopping mall customer navigation and nursing home personnel monitoring, Wi-Fi tags have become a typical case of infrastructure reuse with their "low cost and wide coverage" characteristics.
Ultrasonic tags: "penetration experts" in non-line-of-sight positioning
Ultrasonic tags emit high-frequency sound waves above 20kHz and use the reflection time difference to calculate the position. Its core advantages lie in strong penetration and non-line-of-sight positioning capabilities. Ultrasonic signals can penetrate obstacles such as walls and shelves to achieve a positioning accuracy of 1-3 meters in complex environments. Technically, ultrasonic tags need to be paired with receivers to calculate the distance by measuring the propagation time of sound waves. They are suitable for scenarios such as underground mine personnel positioning and cold chain transportation temperature monitoring. They have low power consumption, but are greatly affected by environmental noise, and signal quality needs to be optimized through filtering algorithms.
The selection of RTLS tags needs to comprehensively consider accuracy requirements, cost budgets, and environmental adaptability. For high-precision scenarios such as automotive manufacturing, UWB tags are the only choice; in large-scale deployment scenarios such as retail and logistics, BLE tags have significant cost-effectiveness advantages; and Wi-Fi tags are suitable for low-cost upgrades for companies that already have a well-developed wireless network.
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