2. A new application method of 45G active radio frequency technology-real-time positioning system for personnel and articles
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2.45G active radio frequency electronic tag (card) is a new category in the field of RFID application technology. Due to the extremely low transmission power of this type of electronic tag, and the wireless data transmission distance in the air can reach nearly 100 meters, and the external environment has little influence on its transmission performance, it has begun to receive great attention from users in the field of radio frequency. As people’s application data for the personnel management and logistics distribution, warehousing and transportation, vehicle channel management and other systems of the 2.45G active radio frequency electronic tag within a limited range can be transmitted through the SMS platform or the Internet, this type of product has shown Very broad application prospects.
With the popularization and application of 2.45G active radio frequency electronic tags, people have discovered that this type of electronic tags (which can encapsulate card shapes for various applications) has many advantages over other RFID products. For example, the induction direction of this type of electronic tag is not obvious. If this type of tag is attached to a metal surface, the impact will be relatively small. This type of tag can also be made into a read-only type and a readable and writable type. If the special data anti-collision method is used to read the sensor, it can also read more than 100 tags at the same time in a short period of time. In the process of applying 2.45G electronic tags, people’s pursuit of product perfection is endless. For example, in the management of migrants in a small area (such as hospital inpatients, kindergarten children, etc.), sometimes managers not only need to know which reading sensor the tag has been read at this time, but also want to know more about this time. Where does the label move at this moment (XN, YN), that is, the label is at the coordinate position originally set at this time. The essential requirement is that such labels are required to have a spatial positioning function. In this way, the passive managers of small-scale activities and the specific locations of the goods in storage and transportation can provide reliable location information to the management system in time, which brings great convenience to the management work.
To realize the positioning function of 2.45G electronic tags, the system must have a widely distributed, simpler, and low-cost address code generator in addition to the data processing part, the reading sense recognition part and the electronic tag. When the person wearing the tag enters the positioning area, the electronic tag receives the address code sent by the address code generator, and immediately sends the address code and the original ID number of the electronic tag to the reader, and the reader is processed The data is transferred to the control system. Through the electronic map, you can know where the person wearing the electronic tag is at this moment at any time. Of course, if someone is equipped with a handheld PDA-type reader at this time, and the electronic tag on the cargo box of the storage system is located, you can use the PDA or the computer network connected to the PDA, and you can also know the specific location of the cargo box. Up.
From this point of view, the system adds an address code generator, which is an indispensable device for a locating RFID system. Its main function is to transmit the programmed address code and to the electronic tag, and at the same time the electronic tag is required to transmit the address code and the ID number of the tag. The key to achieving this function lies in what frequency is used to transmit the address code. After many studies, experiments, and comparisons, it is found that there are multiple frequencies that can be achieved. There is a low frequency (LF) frequency band, and the commonly used ones are 125K～134K. High frequency (HF), commonly used are 433M～445M. And ultra high frequency (UHF) frequency band, even microwave frequency. Using low-frequency carrier frequency as the address code for transmission, low frequency, high power consumption, larger equipment size, and more accurate distance, but the electronic tag identification address code has more obvious directionality, which will affect the use. If high-frequency UHF is used as the carrier frequency to transmit address information, the address range is large, which is not convenient for precise positioning. At the same time, if it is used as a receiving electronic tag, the volume will be larger, and it is not suitable for large-scale promotion and application.
After comparison and practical application, a frequency above 2G is used as the address signal transmission frequency. The directionality of the electronic tag is not obvious, the distance is more accurate, and the volume and cost of the electronic tag are not too high, and the application prospect is relatively broad. Now the RFID real-time positioning system has also been used in small batches in hospitals, schools, underground mines and prisons, and has shown its great application potential. In order to solve the problem of address boundary crossing of electronic tags, system developers have many different methods to solve it. If you add the anti-re-reading address code, it will not be transmitted again after the number of repetitions. When only the address code is changed, the position of the electronic tag will be re-evaluated. Even when the electronic tag leaves the boundary address, an alarm signal will be sent to the location of the guard on duty. Increase the safety of the persons and objects being guarded.
Compared with passive radio frequency electronic tags, the cost of 2.45G active electronic tags is relatively high. However, due to the excellent performance of 2.45G active electronic tags, and the successful application in various fields, good social and economic benefits have been achieved, far exceeding the former. We have reason to believe that the 2.45G RFID instant positioning system has a broader application prospect.
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