In view of the current working frequency of RFID systems, various standards and large gaps, and not suitable for the simultaneous application of multiple tags, the idea of ​​designing RFID readers based on software radio and LabVIEW is proposed. By loading different software codes, simulation reading The device can read and write RFID tags that meet different standards and meet different standards. By comparing with the reading results of the standard reader, the simulation reader realizes reading the information carried by the RFID tag, saving various configurations. The cost of different types of readers. 3 Reader performance test According to the working principle of RFID system and the frequency of working in AAR S-918 standard, firstly, the program of transmitting excitation wave is programmed by LabVIEW software, the carrier frequency is set to 915 MHz, the sampling rate is 800 kHz, and the emission is set. The gain is 30 dB. The front panel of the program and the system block diagram are shown in Figure 3 and Figure 4, respectively. When the tag enters the recognition area of ​​the reader, the information carried by itself is transmitted back to the reader through electromagnetic reflection, and the simulated reader demodulates the reflected ASK signal according to the AAR S-918 standard specification, and according to The encoding rule of the AAR S-918 standard decodes the information carried by it, and the signal processing and decoding procedure of the reader is shown in Fig. 5. Heat Exchanger Accessories is a wide area.It has many parts.We are mainly strong in the air conditioning parts such as radiator,condenser,evaporator,inter cooler,oil cooler,charge air cooler parts in the gas car.Also Trumony is strong in new energy car battery cooling parts,such as heat pipe,brazing water cooling plate,extruded water cooling plate or roll bond water cooling plate.We can also offer engineering solution for the design of the battery cooling unit if you want.A detailed technic communication is very important to understand about your requirement.Bring technology to the ground is the target we are always persuing.Trust in harmony,we care what our clients care. Extruded Aluminum Bar,Aluminum Extrusion Bar,Structural Aluminum Profiles,Heat Exchanger Accessories Trumony Aluminum Limited , https://www.szaluminumcoil.com
0 Introduction Radio Frequency Identification (RFID) is a technology that uses the spatial coupling and backscattering characteristics of radio frequency signals to automatically identify and exchange data with target objects. Therefore, the identification process does not require manual intervention, and has high precision and long life. Easy to operate and other features.
UHF RFID (UHF RFID) has been used more and more in the fields of logistics management, transportation management, factory production control, etc. due to its long recognition distance (up to 10 m). Currently, RFID standards are complicated. There is no more general application standard, so it is necessary to develop a reader that can support multiple RFID tag standards for applications with a wide variety of tags and RFID technology research and development institutes. The characteristics of software radio will be different. The RFID standard is implemented by software code. By loading different software codes, the RFID tags that meet different standards can be read and written. It can be easily solved by purchasing different readers to read and write different types of RFID tags. The problem.
Software radio is a brand-new design idea that has gradually emerged since the 1990s. Its core is to convert different communication modes by loading different communication software on a universal modular and programmable hardware platform. The design idea makes the radio station in communication adapt to different communication modes. The good compatibility and programmability of software radio makes the development of communication system mainly become the research of digital signal processing software. Based on this idea, we can try to put RFID Various standards are implemented in the form of software code, which enables the implementation of RFID readers that conform to various standards by loading different software.
This article uses LabVIEW software developed by National Instruments to write software radio code. LabVIEW is one of the most widely used data acquisition and control development environments in the world. It plays an important role in communication simulation. It uses a graphical programming language. (also known as "G" language) to write programs, the generated program is in the form of a block diagram. LabVIEW is also a general-purpose programming system, there is a huge library of functions to complete any programming tasks, including data acquisition. GPIB. Serial port control. Data analysis. Data Display and data storage, etc. can enhance the ability of researchers and developers to build their own scientific and engineering systems, and provide a convenient way to implement instrument programming and data acquisition systems.
1 Software-based RFID reader model RFID tags need to be first to obtain the excitation signal, and then convert the RF signal transmitted by the reader into a DC regulated power supply through a voltage regulator. Therefore, software radio is required. (simulation reader) first emits the excitation wave. In some safe RFID application protocols, it also includes the security authentication and the process of operating the tag. This requires adding some operation instruction code to the excitation wave to get from the tag. Obtain the corresponding information. The reflected signal of the tag carries its own information. During the reception of the reflected signal, the channel fading, multipath effect, and the receiver itself introduce noise. Therefore, it needs to be filtered before the information is parsed. These effects. The simulation reader uses the same carrier frequency as the excitation wave for coherent demodulation. The framework of the entire RFID simulation reader is shown in Figure 1. 
2 Analysis of tag information This paper reads the RFID tag that complies with the AAR S-918 standard. This standard specifies the operating frequency, transmission/reception bandwidth, modulation mode, transmitter power and coding scheme of the RFID system. . 
The coding scheme is shown in Figure 2. As can be seen from Figure 2, each user data bit is replaced by 8 sub-bits, that is, user data "1" is replaced by "10101100", and user data "0" is used. 11001010" instead. The data frame identification header is "1010101010101100". After filtering the signal reflected by the label, demodulating and other signal processing, the original signal of the baseband is restored. Next, the label carrying information is restored. AAR S-918 standard Using the unique 6 b ASCII encoding, the correspondence of the encoding is shown in Table 1. 
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