There are many parts to an RFID system and a long list of factors that can affect its performance. Often, a system failure creates a chain of responsibilities extending from the end user to the manufacturer, assuming that the reader is defective if the problem cannot be resolved immediately. In fact, many RFID failures are not caused by the reader itself, but by system design, hardware, setup, environment, and other influences entirely within the control of the end user. However, with so many potential sources to choose from, it can be nearly impossible to decide where to start your search, especially if you are not familiar with the ins and outs of RFID systems and operations. Here, we detail the first places to look when troubleshooting a poorly performing RFID system:
Hardware and interference
A good starting point for troubleshooting reads is the basic hardware of the system, as incorrect and/or misplaced components are common causes. Fortunately, they are usually easy to fix too.
The first step in determining if the hardware is the source of the failure is to check the level of electrical noise interfering with any HF system using a tool provided by the manufacturer or some other noise measurement device.
Cable length and type are a common concern for those using RFID systems and a common misplaced location. While 50-ohm antenna cables are standard, not all cables are created equal. Care must be taken to ensure that the ones you choose provide the desired signal and are installed as efficiently as possible.
For HF antennas, the cable length is important; while shorter cables are generally considered to provide a better performance, cables in HF applications suffer from higher losses as they shrink. Instead, they should exactly match the recommendations given by the manufacturer.
In contrast, UHF antenna cables perform best on the shortest possible cables, but specific types of cables need to be carefully selected based on their attenuation. Cables at the lower end of the market have much greater attenuation, causing most of the signal to be lost.
With RFID, the main responsibility of the antenna is to communicate with the transponder to determine the range in which the tag can be detected. It is important to choose the size and type of transponder that meets your system needs.
All HF systems use loop antennas, which generate a symmetrical magnetic field whose magnitude can be adjusted based on the signal strength and the size of the antenna. At the same time, UHF systems use antennas that generate directional fields, the specifications of which vary depending on the respective design. Of the two, the UHF environment is more likely to be the source of poor antenna performance, as the directional field is easily corrupted by objects within its beam angle, resulting in reflections and read holes and islands.
The frequency with which a reader operates forms the basis of its competence. HF and UHF are the two most common passive RFID frequencies, each with unique mechanisms to transfer energy and perform coupling between the reader and transponder. The high frequency of 13.56MHz uses magnetic fields or inductive coupling to perform these tasks, while the UHF between 860 and 960 MHz in FCC countries uses an electric field called backscatter coupling. While choosing the right frequency for your application may seem simple, the truth is that many people don't realize the complexities of possible failures.
To determine if you have chosen the ideal frequency for your application, consider the following factors:
RFID reception is heavily influenced by the materials that the frequency must pass through in order to pass information to the reader; in particular, their density is an important determinant of the frequency best suited for your application. Materials such as water, human bodies, and metals can cause reflections and absorption when using the incorrect frequencies, which can result in poor reader performance.
Applications involving high-density materials are best served by lower frequencies using magnetic couplings, such as HF and near-field UHF.
Again, tag density is a major determinant of the appropriate frequency one should use. If your application needs to read a large number of closely-bundled tags (such as a pile of documents or poker chips) that are collected in a small area, using the incorrect frequency may cause the antenna to detune, thereby detuning the reader No tags could be detected.
Although read speeds for various RFID frequencies can be found from various sources across the market, they are often far from what is observed in real life. In UHF, the same goes for EPC Class 1 Gen 2 transponders, which are generally considered to read up to 1,000 tags per second. In testing, we found that each performed well below these estimates in real-world settings.
When purchasing an RFID reader, people often require direct knowledge of the range capability of a particular reader. However, it is nearly impossible to provide an accurate estimate without first testing the reader in the intended application. This is because the reading distance is affected by many factors: environmental factors, activity density, sensitivity, tag type, size and location, and more.
For example, in the case of collecting multiple low-density tags in a small space, HF and near-field UHF respectively appear as options. However, if there are unrelated tags nearby, HF will prove to be the most suitable; unlike UHF antennas, the range of HF antennas can be precisely controlled.
One area that can be overlooked when trying to track and troubleshoot RFID failures is system security. While this may not be a problem in applications such as inventory tracking, where no private data is logged, in many applications choosing the proper protection for your system is a key concern.
There are several security strategies available for RFID systems, the least of which is password protection of the data collected by the transponder. Among other things, encryption keys can be used to lock user memory or data; however, these keys must be kept carefully to prevent compromise of the entire system. Cryptographic authentication is the highest level of security available, utilizing a transponder running a cryptographic engine or processor, allowing each reader to uniquely encrypt transponder interactions.
In most cases, the failure of RFID systems is not due to a misunderstanding of the technology, wrong setup, or omission of important factors, but rather a failure to realize that there are multiple options on the market, especially when many companies only offer one flavor of RFID technology. If you continue to experience reader glitches that the manufacturer can't fix, it's possible that they simply don't have the best solution for your needs. At the end of the day, gathering application details and using them to guide your decisions will always be the best way to achieve optimal RFID performance.
The above mainly describes the main troubleshooting tips for RFID system failure, if you want to buy a new RFID reader, please contact us
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