Application of DICOM standard in portable medical equipment1 IntroductionRadio frequency refers to the electromagnetic wave with a certain wavelength that can be used for radio communication. Radio frequency identification technology is a non-contact automatic identification technology rising in the 1990s. It uses the transmission characteristics of radio frequency signal and spatial coupling (inductive or electromagnetic coupling) or radar reflection to realize the automatic identification of the identified object. However, at present, there are still many bottlenecks in the development of RFID, and the low data reading rate is one of the main bottlenecks.

This paper will analyze the RFID system by introducing the basic composition and working principle of the RFID system. Combined with the problems encountered in the practical application of RFID system and the reasons for the low reading rate of the system due to the blind area in the reading range of readers, redundant data in different reading points, mutual interference of readers and other factors, this paper puts forward from the following aspects: reasonably optimizing the hardware configuration, perfecting the software design Play the role of middleware and integrate other technologies to improve the data reading rate of RFID system.

2. Basic composition of RFID systemRFID system at least consists of electronic tag (e-tag / transponder, also known as smart tag) and reader (reader / interleaver, also known as reader / writer).Electronic tag is the data carrier of RFID system. Electronic tag is composed of tag antenna and tag special chip. Electronic tags are divided into active tag, passive tag and semi passive tag according to different power supply modes; It can be divided into low-frequency electronic tag, high-frequency electronic tag, UHF electronic tag and microwave electronic tag according to different frequencies; It is divided into * label, linear label, paper label, glass tube label, circular label and special-purpose special-shaped label according to different packaging forms; According to their different working modes, they are divided into active tags and passive tags.

Reader is a device used to read or write electronic tag information. It can be designed into many kinds of products according to specific use environment and requirements. The reader communicates with the electronic tag wirelessly through the antenna, which can read or write the electronic tag identification code and memory data.A typical reader consists of a high frequency module (transmitter and receiver), a control unit, and a reader antenna. Of course, RFID system needs the support of computer and other hardware equipment and software in practical application. Figure 1 shows the composition of a typical RFID system.3 basic model of RFID system

The basic model of RFID system is shown in Figure 2. As the radio frequency carrier, the electronic tag and the reader realize the spatial (contactless) coupling of the radio frequency signal through the coupling element. In the coupling channel, the energy transmission and data exchange are realized according to the timing relationship.Discussion on reading rate of RFID systemThrough the introduction of RFID system, we believe that the main reasons for the low reading rate of RFID system are: there are blind areas in the reading range of readers, redundant data in different reading points, mutual interference of readers, etc. In view of the above problems, we discuss them from the following four aspects.

4.1 reasonably optimize hardware configurationIn terms of hardware, we must first clarify a problem. That's what you really need. Don't blindly think that "the price is expensive, the larger the reading range and the higher the frequency, the better". It is the so-called "tailor-made" that "what suits you" is the best. Based on this understanding, you can choose hardware devices that meet the actual needs.

At the same time, consider all RFID tags and readers as a complete "data network", so as to reasonably optimize the hardware configuration, so as to maximize the efficiency of the whole system. Taking the access control system as an example, in order to prevent the blind area in the reading range of the reader, resulting in missing reading, the number of readers or antennas can be increased to compensate for the defect of blind area in the reading range of the reader; In order to prevent mutual interference between readers, the method of relatively isolating readers or antennas in space can be adopted to avoid mutual interference. In addition, according to the actual needs, the data reading rate of RFID system can also be improved by properly adjusting the antenna layout and antenna transmission power.

4.2 improve software designAt present, the hardware facilities of the optimized RFID system can basically meet the needs of data reading rate. With the decline of reader price, end users can easily deploy a large number of readers in their application sites, which not only solves the problem of missing reading, but also obtains more useful information from these systems. But the new problem is: redundant data reading or cross data reading. A simple description of this problem is that "a tag that should not be read in a certain position is read by a reader that should not read this tag".The core of LV positioning logic is based on "picking out the required readout data from the spatial location and filtering out the unnecessary readout data". The result is that the correct and accurate tag position is extracted from the results obtained by all RFID readers. In short, LV positioning logic is a software algorithm based on eliminating "redundant" readout data according to the data set resident in the whole reader system. Colorwave algorithm gives a good solution to the conflict between multiple readers due to overlapping work ranges.

For electronic tag collision, in the high frequency band, the classical ALOHA protocol is generally used as the tag anti-collision algorithm. The tag of ALOHA protocol is used to avoid conflict by selecting the method of transmitting information to the reader after a random time; In UHF band, tree bifurcation algorithm is mainly used to avoid conflict. In addition, other optimization settings can be made for the software. For example, in the e-ticket system, the scanning time interval of the reader can be designed by software to adaptively adjust the scanning time. In case of large traffic, the scanning frequency of the reader can be accelerated through software control to prevent missing reading; In the case of less traffic, the scanning frequency can be relatively reduced, so as to avoid the emergence of redundant data.

4.3 play the role of MiddlewareRFID middleware is the nerve center in various RFID industrial applications. RFID middleware is a message oriented middleware (MOM). Information is transmitted from one program to another or more programs in the form of messages. RFID middleware plays an intermediary role between RFID tags and applications. From the application side, it uses a set of general application program interfaces (APIs) provided by the middleware, that is, it can connect to the reader and read tag data.Therefore, even if the database software or back-end application program storing RFID tag information is added or replaced by other software, or even the type of RFID reader is increased, the application end does not need to be modified. This not only effectively solves the problem of data reading rate, but also saves other problems such as the maintenance complexity of many to many connections. RFID middleware will have very good development prospects in service-oriented architecture (SOA) and business information security applications in the future.

4.4 integration of other technologiesIntegration with sensor technologyIn the next few years, an important application trend of RFID is the equipment that combines RFID with sensors (such as sensors for measuring temperature and pressure). At present, it has been implemented abroad. Because RFID has poor anti-interference and the effective distance is generally less than 10m, its application is limited. Combining WSN (Wireless Sensor Network) with RFID and using the effective radius of the former up to 100m to form wsid network will greatly make up for the shortcomings of RFID system itself.

Integration with WiMAX, 3G, GPS and other communication technologiesWiMax (global interoperability for microwave access) is simply defined as a wireless broadband data transmission system. The wireless service range of WiMAX can be as far as several kilometers under the condition of maintaining high data traffic in urban areas. Its performance far exceeds the existing wireless network technology. In directional communication connection, the service range can reach 50 km under the condition of maintaining certain data traffic. Due to its extremely high performance, WiMAX technology is considered to be the best backup scheme for DSL UMTS connection.

The integration of WiMAX, 3G, GPS and RFID is moving forward with the active participation of all parties. RFID tag has the characteristics of small volume, large capacity, long service life and reusable. It can support fast reading and writing, non visual identification, mobile identification, multi-target identification, positioning and long-term tracking management. The cost saving and efficiency improvement promote RFID technology to become an important entry point for various industries to realize informatization. They will build a wireless broadband network that can meet the needs of a variety of application environments and generate rich applications, expanding the application field of RFID technology.

Fusion with biometricsBiometric recognition technology is a solution to complete authentication by using automatic technology to measure their physical characteristics or personal behavior characteristics, and comparing these characteristics with the template data in the database. The biometric recognition system captures the samples of biometrics, and the unique features will be extracted and transformed into digital symbols, which are stored as personal feature templates. People interact with the identification system to authenticate their identity to determine whether they match or do not match. At present, the commonly used biometric recognition technologies include fingerprint, palmprint, face, voice, retina, signature recognition and so on.In short, the integration of RFID system with other technologies is imperative, and great achievements have been made. It solves the problem of low data reading rate of RFID system, which will inevitably make RFID technology widely used. Finally, it will go deep as bar code technology and slowly extend to all aspects of various industries, which plays a key role in improving operation efficiency and economic benefits of the industry, so as to promote a new leap in the global economy and have a far-reaching impact on human society.

5 Conclusion

On the whole, the development of RFID system will be better and better in the future. Although there are still some technical and application problems such as low reading rate, we believe that it is not difficult to overcome the current problems of RFID through a series of measures such as optimizing hardware configuration, improving software design, playing the role of middleware and integrating other technologies. Under the strong market orientation, RFID technology will cause a major change all over 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 can be predicted 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 scientific research institutions and enterprises.

Power supply standardIEC 60601-1:2005 and accompanying documents specify the safety and basic functional requirements of the power supply. The standard appears in the form of ANSI / AAMI document in the United States and in the form of "euronorm" in Europe and around the world, with some local differences. Since January 2021, the latest revision (a1:2012, a2:2020) has updated the standard, deleted outdated references, corrected errors and made it better consistent with IEC 62368-1. The current medical EMC standard IEC 60601-2 is the 4th Edition.Built in medical power standard

AC powered medical devices can have "built-in" power supplies or lower power external adapters. If it is an internal product, the product designer should consider high voltage and high energy, and usually choose to buy a "medically certified" power supply. However, the final product is the product certified for this application, so there are other considerations, such as labels, connectors, internal wiring of power supply and fuses.

Due to grounding, external wiring and interference from other noise sources, the built-in power supply conforming to EMC standards cannot be guaranteed to pass the test. A common practice is to add another EMI filter at the AC inlet, which may be included in the connector. However, it should be noted that the leakage current limit should not be exceeded. For the most stringent CF product rating, the leakage current limit can be as low as 10 a. The leakage of external filter may directly lead to the internal leakage of AC power supply, there is a risk of interaction between external filter and internal filter, and may even worsen EMI.

Secure power solutionsThe safe solution should select the target application and specify a power supply with 2 x MOPP certification and EMC compatible performance. For example, power supplies from recom racm230-g, racm550-g and the recently released racm-1200v series.Their peak or rated power is 230W, 550W and 1200W respectively. When fans are not allowed (usually in medical environments), these products can be floor cooled. All products have 2x MOPP / 250V AC rating to prevent leakage to ground (racm550 / 1200). The safety barrier in each recom power supply is shown in Figure 2.

Figure 2: safety fence racm230 / 550 / 1200 seriesFigure 3: a 2x MOPP DC / DC converter provides SIP / SOP isolationUsing a medically certified power supply (such as the power supply of recom) is a reliable way to ensure that the safety and EMC standards required by various medical application environments are met. It would be a lower overall cost approach if development, certification costs and time to market were taken into account.

Recom is a good choice when selecting AC / DC power supply for medical equipment. Eurotime electronics, as a distribution partner of recom, provides local inventory and technical support.Original title: eurotime classroom | AC / DC power supply in medical applicationsThe source of the article: WeChat official account: Euro time electronic RS] welcome to add attention! Please indicate the source of the article.