The online dissolved oxygen sensor of the optical method uses the fluorescence method to measure the dissolved oxygen content in water. The dissolved oxygen probe uses advanced optical technology to achieve high-precision dissolved oxygen measurement. The response speed is fast, and it can monitor the change of oxygen in water in real time. The optical dissolved oxygen sensor has high stability and can work stably for a long time. The protection level is IP68, and it can work continuously underwater. The maintenance and calibration of the dissolved oxygen sensor is relatively simple. The optical method does not require electrolyte and routine maintenance. The service life of the fluorescent cap is about 1 year, and the reliability is high. The optical dissolved oxygen sensor is small in size, light in weight, easy to install, and suitable for various water body environments. We have three types of Optical Dissolved Oxygen Sensors, PPS housing with 1 inch mounting thread and Titanium for marine aquaculture use. These dissolved oxygen sensors are all digital output, which is convenient for users to integrate into different systems.
Online Dissolved Oxygen Sensor,Digital Dissolved Oxygen Probe,DO Probe Suzhou Delfino Environmental Technology Co., Ltd. , https://www.daruifuno.com
This article will analyze the RFID system by introducing the basic components and working principles of the RFID system. Combining the problems encountered in the practical application of the RFID system and the reasons for the low read rate of the system due to factors such as blind spots in the reader reading range, redundant data stored in different reading points, and mutual interference between readers, Optimize hardware configuration, improve software design, play the role of middleware and integrate other technologies to improve the data reading rate of RFID system.
First, the basic composition of the RFID system
The RFID system consists of at least an electronic tag (E-Tag/Transponder, also known as a smart tag) and a reader (Reader/Interrogator, also known as a reader).
The electronic tag is a data carrier of the radio frequency identification system, and the electronic tag is composed of a tag antenna and a tag-dedicated chip. Electronic tags are classified into active tags, passive tags, and semi-passive tags according to different power supply modes. They are classified into low-frequency electronic tags and high-frequency electronic tags according to different frequencies. , UHF electronic tags and microwave electronic tags; according to the different packaging styles are divided into labels, linear labels, paper labels, glass tube labels, round labels and special-purpose shaped labels; according to their working patterns are divided into active Labels and passive tags.
The reader is a device for reading or writing electronic tag information, and can be designed into a plurality of products according to the specific use environment and needs. The reader wirelessly communicates with the electronic tag through the antenna, and can read or write the electronic tag identification code and the memory data.
A typical reader includes a high frequency module (transmitter and receiver), a control unit, and a reader antenna. Of course, in practical applications, RFID systems also require support from other hardware devices such as computers and software.
Two, the RFID system as a basic model <br> <br> between the electronic tag reader and a radio frequency carrier spatial (non-contact) coupled to a radio frequency signal by the coupling member, in the coupling channel according to the timing relationship, to achieve energy transfer , the exchange of data.
Third, the RFID system read rate problem
Through the introduction of the RFID system, we believe that the reason for the low reading rate of the RFID system is mainly because there are blind areas in the reading range of the reader, redundant data in different reading points, and mutual interference between readers. In response to the above problems, we will explore the following four aspects.
1. Reasonable optimization of hardware configuration In terms of hardware, it is first necessary to clarify a problem. That is what your real "what is the demand." Don't blindly think that "the price is high, the reading range is larger, and the higher the frequency, the better." The so-called "tailor-made", "fit" for yourself is the best. Based on this knowledge, you can choose hardware devices that match your actual needs.
At the same time, consider all RFID tags and readers as a complete "data network" to optimize the hardware configuration to maximize the overall system. Taking the access control system as an example, in order to prevent the blind reading area of ​​the reader from being hidden, which may lead to missed reading, it is possible to compensate for the defect of the blind spot in the reading range of the reader by increasing the number of readers or antennas; The readers interfere with each other and can be spatially isolated from the reader or antenna to avoid mutual interference. In addition, according to actual needs, the data reading rate of the RFID system can also be improved by appropriately adjusting the antenna layout and the antenna transmission power.
2, improve the software design At present, through the optimized configuration of the RFID system hardware facilities can basically meet the data read rate needs, and as the reader price drops, the end users can easily deploy a large number of readers in their application sites, This not only solves the missed reading problem, but also gets more useful information from these systems. But the new problem that comes with it is: redundant data read in or cross data read in. A brief description of this problem is that "a label that should not be read at a location is read by a reader that should not read the label."
The core of LV positioning logic is based on "picking out the required read data from the spatial location while filtering out unwanted read data." The result is that the correct and accurate label position is extracted from the results obtained by all RFID readers. In short, LV positioning logic is a software algorithm based on the elimination of "excess" readout data based on the data set that resides throughout the reader system. The Colorwave algorithm gives a good solution to the problem of conflicts between multiple readers due to overlapping working ranges.
For electronic tag conflicts, in the high frequency band, the anti-collision algorithm of the tag generally adopts the classic ALOHA protocol. The label of the ALOHA protocol is used to avoid collisions by selecting a method of transmitting information to the reader through a random time; in the UHF frequency band, a tree branching algorithm is mainly used to avoid conflicts. In addition, other optimization settings can be made to the software. For example, in an electronic ticketing system, the reader's scan time interval can be designed by software to adaptively adjust the scan time. For the case of large traffic, software control keeps the reader's scanning frequency faster and prevents missed reading. In the case of less traffic, the scanning frequency can be relatively reduced, thus avoiding the occurrence of redundant data. .
3, play the role of middleware RFID middleware in the various RFID industry applications in the nerve center. RFID middleware is a Message-Oriented Middleware (MOM). Information is transmitted from one program to another in the form of a message. RFID middleware acts as an intermediary between the RFID tag and the application. From the application side, a set of common application programming interfaces (APIs) provided by the middleware can be connected to the reader to read the tag data.
Therefore, even if the database software or the back-end application storing the RFID tag information is added or replaced by other software, or even the type of the RFID reader is increased, the application side does not need to be modified. This not only effectively solves the problem of data read rate, but also saves other problems such as maintenance complexity of many-to-many connections. In the future, RFID middleware will have a very good development prospect in the application of Service Oriented Architecture (SOA) and commercial information security issues.
4, integration of other technologies and sensor technology integration In the next few years, an important application trend of RFID is the combination of RFID and sensors (such as sensors for measuring temperature and pressure), which has been implemented abroad. Due to the poor anti-interference of RFID and the effective distance is generally less than several 10m, this is a limitation for its application. Combining WSN (Wireless Sensor Network) with RFID and using the former with an effective radius of up to 100m to form a WSID network will greatly compensate for the shortcomings of the RFID system itself.
Integration with communication technologies such as WIMAX, 3G, and GPS. WiMAX (Worldwide Interoperability for Microwave Access) is simply defined as a wireless broadband data transmission system. WiMAX's wireless service range can be as long as several kilometers in the case of high data traffic in urban areas. Its performance far exceeds the existing wireless network technology. In the case of directional communication connection, the service range can maintain certain data traffic. Up to 50km, due to its extremely high performance, WiMAX technology is considered to be the best alternative for DSLUMTS connections.
The integration of WiMAX, 3G, GPS and RFID is constantly moving forward with the active participation of all parties. RFID tags are small in size, large in capacity, long in life, and reusable. They support fast reading and writing, non-visual recognition, mobile recognition, multi-target recognition, positioning and long-term tracking management. The cost savings and efficiency increase have made RFID technology an important entry point for informationization in various industries. They will build a wireless broadband network that can meet the needs of multiple application environments and generate rich applications, expanding the application field of RFID technology.
Fusion with biometrics. Biometrics technology is a solution to perform authentication by using automatic techniques to measure the physical characteristics or personal behavior characteristics of the system and compare these characteristics or features with the template data of the database. The biometric system captures samples of biometrics, and the unique features are extracted and converted into digital symbols that are stored as individual feature templates. People interact with the identification system to authenticate their identity to determine a match or a mismatch. Currently used biometric recognition technologies include fingerprints, palm prints, face, voice, retina, signature recognition, and the like.
In short, the integration of RFID systems with other technologies is imperative, and great results have been achieved. Solving the problem of low data reading rate of RFID system, it will definitely make RFID technology widely used, and will eventually be as deep as the bar code technology and slowly extend to all aspects of various industries, which is the key to improve the efficiency and economic efficiency of the industry. Sexual effects, thus promoting a new leap in the global economy, have a profound impact on human society.
Fourth, the conclusion
Overall, RFID systems will become better and better in the future. Although there are still some technical and application problems such as low read rate, we believe that hardware optimization, hardware design, and middleware are optimized. A series of measures, such as the role and integration of other technologies, are not difficult to overcome the current problems of RFID. Under the strong market orientation, RFID technology will surely cause a major change in the world. It will become a new economic growth point in the future, and will eventually become the largest information technology support for the development direction of Chinese enterprises. It is foreseeable that in the near future, as a global manufacturing base, China will be the world's largest RFID application market in the future. This will be a rare opportunity for domestic research institutions and enterprises. 
Radio Frequency refers to electromagnetic waves that have a certain wavelength for radio communication. Radio Frequency Identification (RFID) is a non-contact automatic identification technology that began in the 1990s. It uses radio frequency signals and spatial coupling (inductive or electromagnetic coupling) or radar reflection transmission characteristics to achieve identification. Automatic identification of objects. However, as far as the current situation is concerned, there are still many bottlenecks in the development of RFID, and the low data reading rate is one of the main bottlenecks.