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Top 5 Reasons Why Your RFID Reader Does Not Work

rfid in warehouse

Designing and using a RFID reader can also be a huge challenge. If you are not familiar with RFID technology, you might don’t know how to apply it in your field.

The following are the most common pain points we have found in providing RFID services and testing solutions to our customers for more than 10 years.


1. Reader sensitivity


The scope limitation of RFID tags is a thing of the past.

Today’s state-of-the-art labels require very little energy and can be powered over a range of more than 20 meters.

To achieve these ranges, readers need to be able to pick up even faint signals from more distant tags.

The industry has seen an improvement in tag sensitivity, so RAIN RFID applications have become a limit for returning links.

This means that the reader cannot hear the tag answer due to the weak backscattering range, which is one of the main reasons for deployment failure.

Therefore, in many successful RFID projects, the sensitivity of the reader is a key task.

In order to overcome this challenge and improve the accuracy and reading rate of readers, a new generation of readers need to be highly sensitive and able to cope with changes in tag parameters, such as the tolerance of backscatter link frequency (BLF), as well as changes in system parameters, such as phase shift.


2. Lack of standardization of readers and writers


RAIN RFID readers must comply with ISO and GS1 standards as well as radio rules.

Pre-testing existing standard readers is not only difficult, but also a long and time-consuming process.

In fact, only some of the tests are done reasonably and effectively.

The engineering team struggles with time pressure, lack of automation, or simply knowledge of the standards required for normative testing.

This can easily lead to insufficient test coverage of the reader.

In order to make all the readers on the market more comparable based on the values defined by the Gen2 protocol, and to improve the performance of RFID deployment, the measurement of link timing, physical layer and RF envelope parameters is essential.


3. Reader gap


The word “Reader Gap” first appeared in 2017, when the new generation of RAIN RFID tag chips had a reading range of more than 20 meters.

While this has aroused great enthusiasm among system designers, there is soon a disadvantage that the overall scope of implementation is usually much lower than this.

Due to the low performance of the reader receiver, the “reader gap” determines the loss of the working range of the RAIN RFID system.

The working scope is the actual range or distance that can be achieved in the application.

The minimum distance of the forward link from the reader to the tag is determined by the maximum transmit power, which is usually limited by radio rules and the minimum operating power Pmin of the tag.

The return link from the reader to the tag is determined by the tag backscatter power Pback and the reader receiving sensitivity.

In order to build a bridge between the tag and the reader, the reception sensitivity of the reader is an important parameter, which depends on the signal phase, frequency (BLF) and antenna gain.

Frequent 6db changes mean a loss of half the range.

reader gap

Figure 1 shows the operating range when using a high-end gate reader (sensitivity-85 dBm), a conventional fixed reader (sensitivity-75 dBm), and frequently using a handheld low-cost reader (sensitivity is only-65 dBm).

These values range from 25 meters to 12 meters to less than 6 meters in free space, which is even lower in harsh conditions.

This gap in the scope of work is caused by the reader, so it is also known as the reader gap.


4. The speed at which the protocol is lost


Understanding and correct use of RAIN RFID air interface protocols, namely ISO/IEC18000-63 and GS1 UHF EPC Gen2, as well as all its commands and parameters, is essential for high-speed access to readers and successful RFID applications.

When deploying a RAIN RFID system, read this interesting white paper from the RFID Alliance on air interfaces and protocol considerations.

According to the RAIN Alliance, there will be 28 billion tags on the market by 2021, and these tags require advanced air interface processing to effectively read the tags needed in the application.

For example, it takes about 5 milliseconds to read RAIN luggage tags, however, if the box contains five pairs of shoes with RAIN tags embedded, a dozen new clothes, a conference badge and more, then a suitcase moves 1 meter instead of 5 centimeters on the conveyor belt until it is identified.

For this reason, the understanding of air interface communication, the selection of correct protocol parameters and the use of protocol software routines are the key to successful application.

Sniffing tools can show whether filtering instructions about data content (such as IATA baggage AFI 0xC1), such as Select and Query, are correctly applied and used in the air interface.


5. Reading rate


People usually have strong expectations for the reading rate.

The effect depends on the selection of the correct tag and reader, tag placement, reader antenna, environmental parameters, but also depends on the priority of the application.

Will it be significantly faster to identify all tags first, or to miss some tags?

To this end, it is important to understand how collision arbitration works and whether the label cannot be read because of a weak signal.

While ensuring that there is less interference with the use of multiple readers, pay attention to the minimum radio frequency energy of the transmission power of the reader.

Testing is another key factor in achieving a high reading rate.


In addition to RFID readers, sometimes if you cannot detect the RFID tag, it might be the problem with your tags. Click here to learn the 6 main reasons why your RFID tag stopped working


Click here to learn more about the products that you can use in your project. If you are not sure, welcome to contact us any time.

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