Category: Blog

About the author

15Teemu Ainasoja

I am VP, Marketing and Sales at Voyantic. I have over 15 years of experience from the RFID industry in Europe and the USA. I have two master's degrees: in industrial engineering and in marketing, and two patents in auto-ID technology. I am actively participating in RAIN RFID alliance activities.

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Best Practices for RAIN RFID Label Quality Testing

Oct 06, 2025

RAIN RFID, aka UHF RFID aka EPC RFID, is the technology used in connecting billions of everyday items to the Internet. RAIN tag production is forecasted to reach 115 billion units by 2028. We are seeing this strong growth continue. As a result, huge amounts of new production capacity will be needed, which means that 

  • more machines are needed,
  • single-lane machines need to be converted into multilane machines, and
  • machine lane speeds must be increased.

At the same time, RAIN RFID users have started to pay more attention to their RFID label quality.

In this article, I will share Voyantic’s experiences and views on RAIN RFID quality testing:

  • What is essential in planning quality testing in RAIN RFID label manufacturing?
  • What are the current best practices in RFID quality testing?

What does good manufacturing quality mean for RAIN RFID tags?

At the very basic level, the good manufacturing quality of RAIN RFID tags could be defined as: “Manufactured RAIN RFID tags are not defective.” This definition is easily understandable, but it does not offer much practical help. In fact, it is misleading.  Sometimes “not defective” is interpreted as “can be read”, and that leads to problems. When RAIN tags start to break, their read range gradually decreases and, only at the very end, the tags become entirely unreadable. 

A better definition of good RAIN RFID manufacturing quality is: “Manufactured RAIN RFID tags’ sensitivities are within set variation limits”. This definition is a bit more technical, but let’s break it down:

  • Tag sensitivity describes how much power is needed for waking up a tag. Tag sensitivity is at the background of all practical performance features. For example, if a tag’s read range has changed, also its sensitivity has changed. If a tag’s orientation pattern (read range in different angles) has changed, also the sensitivity has changed. If a tag’s response strength (backscatter) has changed, the sensitivity has also changed. Shortly – any change in a tag’s performance can be seen as a change in the tag’s sensitivity. Or the other way around – if the sensitivities of two individual tags of a model are the same, they will perform similarly in every way.
  • Variation refers to consistency. Tag designs are different. Some tags are designed to have lower sensitivity (shorter read range) than others. The consistency of the performance within a tag model is important for the users. 
  • Within set limits implies that there are limits, but offers some freedom for setting the criteria. Some applications require exact read ranges – an item moving past a reader on a conveyer belt may require read ranges within some centimeters. Shorter range causes missed reads, and a longer range would risk stray readings – reading unwanted items that are not on the belt but nearby. Some applications have a higher tolerance, and a read range variation of a couple of meters may not be a problem.

RAIN RFID manufacturing quality is good when “Manufactured RAIN RFID tags’ sensitivities are within set variation limits”. This definition also works from a practical point of view.

What does the RF performance of RAIN RFID tags mean?

From a practical point of view, the RF performance of a RAIN RFID tag defines 

  • how far the tag is readable
  • at different angles
  • when the tag is attached to an item.

In tag datasheets, these are commonly described with graphs.

  • An orientation pattern shows how well a tag can be read when it points to a reader from different angles.
  • A threshold curve shows the tag sensitivity – how much power is needed to wake up the tag at different frequencies. A version of the threshold curve may show read range instead of power. 
Picture: Threshold sweep and orientation graphs from Tageos EOS-500 datasheet

Good quality manufacturing produces tags that have consistently similar orientation patterns and threshold curves. The good news for manufacturers is that full measurement is not needed to check that the tags are similar to each other. In fact, this can be checked with minimal test procedures.

How should RAIN RFID tag quality be tested in manufacturing?

It should be kept in mind that one method does not fit everyone. However, RAIN RFID industry seems to be converging towards the following methodology. 

These are the current best practices:

  1. Far-field performance of the tag is tested
  2. Test recipe that separates good and bad tags efficiently
  3. Cross reading is reliably prevented

These best practices may seem simple and obvious, but there are details to consider. Let’s look at these key points in detail.

1. Far-field performance of the tag is tested

In production machines tags are close to each other. Close proximity reading is needed for preventing cross-reading, and for practical reasons. At the same time, a quality test needs to address the far-field performance of the tag. A common near-field antenna cannot be used. Voyantic has solved this close proximity vs. far-field conflict with the patented Snoop Pro antenna concept. This unique antenna requires the tag to use its far-field properties in close proximity.

2. Test recipe that separates good and bad tags efficiently

Separating good and bad tags is an obvious requirement. But how to do it efficiently, at production speeds, when tags fly over the antenna at high speeds? A current best practice test recipe is often referred to as the “three-point test” or “3-point test”. The three-point test recipe includes 

  • testing the tag at three different frequencies across a wide frequency band (hence the 3-point test name)
  • checking that the tag sensitivities are within 3 dB from each other (+/- 1.5 dB)
  • checking that the tag’s EPC code can be inventoried

This is how the test recipe is created:

  • A good starting point is to set test frequencies to 820 MHz, 950 MHz, and 1080 Mhz
  • Adjust one of the points to match the tags’ lower resonance frequency
  • If possible, adjust another frequency to match with the tags’ upper resonance frequency. 
  • select third frequency so that the frequency spread is at least 100 MHz
  • at least one of the points should be an inventory test (for reading EPC)
  • at least one of the frequencies should be a sensitivity test, with 3dB between upper and lower limits
  • the power level for the points should be set so that tag sensitivity in each point is within 3 dB, or +/- 1.5 dB 

Considering the recipe, this 3-point test could be described as the current industry best practice.

Picture: 3-point test recipe as seen in the Tagsurance® 3 recipe builder

In the sample tag (above graph)  both resonance frequencies (868 MHz and 995 MHz) are in the available frequency range. The sensitivity test is set to the lower resonance frequency and the point test is set to the upper resonance frequency. Because the frequency spread is over 100 MHz, the third frequency is set in between. An inventory test is set to this frequency. 

In the above picture, the curve is a median performance tag’s threshold sensitivity curve (reference).

Shows sensitivity test frequency and power range, in addition, a 3 dB range is set for the acceptance criteria. the frequency is set to the lower resonance frequency.

Shows the point test frequency and power. The power level is set 1.5 dB above the threshold of a median performance tag.

Shows the Inventory test frequency and power (for reading EPC/UII code).

3. Prevent cross-reading

Cross-reading occurs when one tag is thought to be read, but in fact, data comes from another, nearby tag.

In normal use, RAIN RFID tags are inventoried. They are read with a speed of more than a hundred tags per second. Testing production quality is different. Tags are tested one at a time, and it is critical to be sure that the results are from the right tag, even if another tag is just millimeters away. And to add to the complexity, all has to happen while the tags move at high speeds across the antenna. 

Voyantic’s Snoop Pro antenna concept includes a method for completely preventing cross-readings. The antenna concept includes a shielding plate with dimensions matched to the inlay’s antenna and repeat length dimensions. This solution assures that cross-readings do not occur.

In addition to the above comments, 2 more notes can be added from the manufacturing point of view.

4. Speed

Production is about the combination of speed, capacity, and quality. Quality testing UHF RFID tags should not be the bottleneck for production. If any machine output needs to be limited because of quality testing, this would add to the cost of quality.

Voyantic Tagsurance 3 system is designed for high-speed production lines, for continuous production use. 

5. Automation

RAIN RFID tags are manufactured in volumes in different machines. Production runs are in millions, and any sample testing is not possible in practice. A common requirement is that tags of unknown quality are not accepted, this forces testing to cover 100% of the manufactured tags. 

The testing must be automated and integrated into the manufacturing machine. 

Voyantic Tagsurance 3 system can be easily integrated into any machine. 

Are there quality standards or specifications to follow? What about quality certifications?

Common quality standards and practices such as ISO9000 series standards and six sigma can be applied to RAIN RFID. However, these standards do not offer practical advice on acceptable quality limits. 

Exact quality limits have emerged within the RAIN RFID industry. The above-mentioned three-point test and tag sensitivity variation within 3dB is a commonly accepted good practice.

ARC RFID lab is offering quality certification for UHF RFID / RAIN RFID inlay manufacturers as a part of their tag certification program. Correctly implemented three-point test using Voyantic Tagsurace system meets these requirements.

The 3dB variation and three-point testing cannot be used every time – adjustments may be needed. The quality requirements arise from the RAIN RFID / UHF RFID users’ consistency requirements. If an RFID user needs very tight read range tolerances, a smaller variation limit may be needed, and in some cases, wider tolerances may be perfect for the customer. 

Learn more about 3-Point Testing with Tagsurance 3

On-Demand Webinar: RAIN RFID 101 for Label Converters

Watch the 60-minute crash course on RFID essentials

Why are your customers talking about RFID now?  What specifically is RAIN RFID? How can you get going? What do you need to consider to avoid claims and rework?

Watch now

This text was published 2022 for the first time and was republished with edited content in 10/2025.

About the author

22Jukka Voutilainen

I am the Co-founder and General Manager of Voyantic, a company that specializes in RFID test and measurement solutions. Before starting Voyantic in 2004, I worked as a researcher at the Helsinki University of Technology focusing on passive RFID sensing for moisture in building structures.

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Read more of Tagsurance 3

RAIN RFID Is Evolving – An Industry Pioneer Looks Years Ahead

May 02, 2025

The global use of RAIN RFID is skyrocketing. Application areas are diversifying, and quality requirements are becoming more stringent. At the same time, tags are increasingly integrated directly into products rather than applied as separate labels. Industry pioneer Voyantic believes the next major step in the RFID sector is a shift toward networked, intelligent, and transparent quality management. The company’s latest product release, version 4.0 of Tagsurance® 3, is designed to support this direction.

Key Updates Propel RFID Technology Forward

The new version combines two major advancements: network connectivity and encoding functionality. According to Voyantic General Manager Jukka Voutilainen, these features make it possible to examine the entire RFID production process from a new perspective.

“The combination allows testing and encoding to take place at different stages of production, and the collected data can be integrated into a comprehensive quality management dataset”, Voutilainen explains.

Voyantic’s systems now enable precise measurement of the electrical performance of tags. The encoding feature adds a completely new dimension: verification and management of the data content. At the same time, the system has been designed to scale and connect securely to the internet, enhancing usability in large, cross-company production chains.

Three Trends Shaping the Industry

Voyantic’s development work is guided by a clear long-term vision: RAIN RFID technology has to be reliable and care-free for the end users. Voutilainen identifies three major trends that are steering the industry in the coming years.

The first trend is the integration of tags directly into products. When an RFID tag is embedded directly into the product, such as a tire or a medical syringe, it can no longer be easily replaced or tested outside the product. This means testing must occur not only before integration but possibly afterward as well. In such cases, the cost of failure can be high: a faulty tag may compromise the entire product. Quality assurance must therefore adapt more precisely to different production workflows. The modularity of Tagsurance 3 supports flexible implementation across various processes.

The second trend involves the expansion of quality expectations throughout the supply chain. Traditionally, tag quality has been enforced at chip bonding, the process step where the tag IC is attached to the antenna. It still remains the single most critical production phase. However, the end users see the quality of the tag after it has passed through various process steps, where the tag’s performance may be impacted. In addition, the supply chain often consists of multiple different parties, such as converters and service bureaus. Tagsurance 3 is designed with this in mind: it can collect and combine quality data from multiple production phases, enabling a broad and transparent view of the process.

The third trend is combining multiple data sources to ensure tag quality. Electrical performance alone is no longer sufficient— a tag may seem to work seemingly well but ends up failing prematurely in the end application. Failures like this can be identified and corrected by combining other process data with electrical performance in quality verification. Secondly, the tag also needs to contain correct and reliable information. When encoding is integrated with product data in backend systems, it becomes possible to verify tag authenticity or link it precisely to a specific item or batch. This opens new opportunities in sectors where traceability and data security are essential.

“Tagsurance 3 is built to support these industry shifts. It’s not just a testing device—it is a system that integrates quality, data, and production management in a new way”,  Voutilainen says.

The Need for Testing Will Not Decrease—Quite the Opposite

While RAIN RFID tags are already widely used in retail, emerging applications such as logistics, pharmaceuticals, and food products are imposing new requirements on the technology. In these areas, the tolerance for quality issues is minimal, and the importance of quality assurance continues to grow.

“The need for testing will certainly not decrease in the future”, Voutilainen affirms.

According to him, technological development will increasingly be shaped by customer needs and the specific requirements of different industries. The company continues to develop its products in close collaboration with customers and actively contributes to the creation of new industry standards.

“Testing systems must evolve in step with applications and demands. Our role is to be at the forefront of that progress”, Voutilainen concludes.

About the author

17Sami Rautanen

I’ve been working at Voyantic since January 2019, nowadays I work as a Senior HW Designer in our HW team. I do mainly RF and electronics design for our products, but I also know something about mechanics, programming and business administration. Sometimes I feel surprisingly extroverted and might even speak in a webinar or write a blog post.

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Do you want your RFID tags to match the future needs of consumers?

RAIN RFID: A Decade of Growth and the Path Forward

Jan 20, 2025

It has been almost four years since I wrote about the possibilities for the RFID industry in this decade. I figured that now would be a good time to review whether that jabbering was making sense and see how the industry has evolved during these past years. This text focuses on RAIN RFID.

The five megatrends I previously estimated that would be important drivers for the RFID industry were:

  • The development of science and technology
  • Overconsumption of resources
  • The amount of waste increases
  • Population growth and the aging of the population
  • The development of healthcare

The tag manufacturing volumes are a clear indicator of the industry moving forward. If the >20 percent annual growth for the RAIN tag manufacturing is correct, then over 50 billion were manufactured in the year 2024 and ~150 billion RAIN tags will be manufactured when we get to 2030. Not too shabby. At some point, the growth will inevitably get slower, but the market is still young and full of potential, so we can still expect quite impressive growth numbers for the industry.

An exited fellow with wristwatches on both hands pointing happily at skyrocketing sales numbers.
An excited fellow with wristwatches on both hands pointing happily at skyrocketing sales numbers.

As for market penetration, retail is still the leader when it comes to volume, but pretty much every relevant sector is expected to have >20 % CAGR in the coming years. The pharmaceutical/healthcare is also steadily growing and that is one of the sectors I listed as a possible driver for the RFID industry. Although the sector is growing, I did most likely overestimate the effect that the population aging, and counterfeit medicine have on the RFID industry.

Sustainability has much more impact on the volumes than the population aging. The overconsumption of resources is one of my favourite topics. I hate wasting pretty much anything: food, clothes, time, you name it. In this aspect, most companies are no different and that can be interpreted from the answers for how the customers see the value they get for buying RFID systems. Sustainability continues to be one of the biggest drivers for the RFID industry. Waste is not wanted.

Latest developments in the RFID industry

Okay, so they’re selling a lot of tags and estimate that to continue to the foreseeable future. That is no excuse to rest on your laurels; the industry needs to evolve and look for new opportunities. In that aspect, some interesting things are now on the table.

The EU is well known for its obsession with regulating every tiny little thing, and the RFID industry should take advantage of that. The upcoming Digital Product Passport (DPP) is an opportunity for the RFID industry, but it must be done right. For DPP, the value lies in sustainability. One of the things I was talking about in the previous blog was that RFID is not yet present in every step of a product life cycle, and DPP can add to it.

Thinking back on the product lifecycle and how RFID does not cover it fully, the part missing is the end user part of the life cycle. With only a couple hundred thousand handheld RAIN RFID readers sold yearly, it would be crazy to expect everyone to soon walk around with a reader in their pocket, right? Maybe not. Everyone (well, almost everyone) already carries a smartphone, and if that thing could be used as a RAIN RFID reader, there could be some nice opportunities to find ways to add value to that.

An empowered end user realizes she now possesses the capability to read RAIN RFID tags with her smartphone.
An empowered end user realizes she now possesses the capability to read RAIN RFID tags with her smartphone.

These development steps are drivers for circular economy and tags being embedded into items, not just separate labels that can be cut off. In some product categories, like car tires, some items are already tagged, so a Proof of Concept has already been done. Tagging items will bring some demands for the tag designs and testing/encoding:

  • Durability: If the tags should be functional throughout the tagged item life cycle, durability can be a challenge.
  • Sustainability: When a tag is part of an item, how can it be recycled? Some development steps have been taken; for example, plastic-free tags are already available.
  • Chip design: Data retention is one important thing if tags are supposed to be working for years, first throughout the supply chain and then in the hands of end users. Some applications might require more memory, of course depending on what information is needed to be stored in the tag memory.
  • Testing/Encoding Tagged items: It might be hard to use the same manufacturing lines for inlays and tagged items; investments for new systems are needed.

Summoning dark clouds

Last time, I didn’t talk much about possible threats to the RFID industry; it was all about the possibilities and good stuff. Let’s try something different this time. What kind of threats is the industry facing? I like investing in stocks, and sometimes, I try to come up with business-breaking scenarios when assessing the risk profile. Which kind of black swans could surprise and really hurt the RFID industry? I thought of three different scenarios:

  • Other technologies replacing RFID: Some other technology or combination of technologies could solve the same problems as RFID. How do we battle that? It all lies in the value provided by the RFID technology, that value must be higher than that of the technologies competing with it. The industry must evolve to answer future needs; standing still is hardly the winning strategy.
  • Radio spectrum reallocation: It’s not enough to compete against technologies trying to solve the same problems as RFID; there is a limited space in the radio spectrum, and there are other users who would love to get it. Allocating the current RFID frequencies for some totally different use would hurt a lot. Why would this ever happen? The same thing applies here as in the previous one: providing more value than the competitors is the key.
  • Security and privacy: The more the markets are flooded with RFID tags and data (this is wanted), the more opportunities there are for mischief (this is unwanted). Moving forward and evolving must not happen without taking this seriously. Fortunately, many other technologies have faced similar issues, and there is no need to reinvent the wheel. Then why is this important? Because if this goes wrong even once, coming back from that and gaining customer trust won’t be easy.
Black swan destroying RFID technology, represented by a warehouse.
Black swan destroying RFID technology, represented by a warehouse.

Grim, that’s for sure. This is not to say that these scenarios are likely to happen, but work must be done to prevent them from happening. Maybe they’re more like grey swans, not really black ones?

All in all, I think the future is looking bright for the RFID industry, and based on the growth estimates by the RFID industry players, others do, too. The growth drivers are there; now, the industry just needs to deliver. At the same time, taking an active part in the latest technological developments and different kinds of regulatory matters should ensure that RFID stays proactively on top of things.

About the author

15Teemu Ainasoja

I am VP, Marketing and Sales at Voyantic. I have over 15 years of experience from the RFID industry in Europe and the USA. I have two master's degrees: in industrial engineering and in marketing, and two patents in auto-ID technology. I am actively participating in RAIN RFID alliance activities.

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Emerging Technologies and Expanding Applications – A Look into RFID Research in 2023

Jun 26, 2024

It seems to have become a yearly tradition that, at the beginning of the new year, I have a glance at the RFID research published in the past year to get an indication of what the future might bring to our business. This time, we are already six months into the new year, but as they say, better late than never! 

If you want to take a broader look back, you can look at our previous recaps from February 2021, February 2022, and January 2023. Sometimes, having a look back can be a great indicator of what the future might bring to our business.

The following analysis examined the headlines of RFID research articles published in 2023 in Google Scholar. There has, undoubtedly, been an impressive selection of fascinating research topics, which means I can’t include all topics and papers in this analysis even if I wanted to. But let’s look at some of the most exciting topics and trends of 2023.

Application-oriented research seems to be on the rise, which is understandable given the industry’s growing and maturing. RAIN RFID use is expanding rapidly to include volume use cases outside of retail, such as healthcare, logistics, manufacturing, and many other fields. Application research supports this market development.

Research expanding from technology development to technology use is a positive sign. The spread of types of applications tells about the applicability of RAIN RFID in several areas.

RFID Sensing in Healthcare

Integrating RFID technology, sensors, and medical diagnostics advances biomedical sciences to a whole new level. This is an interesting and growingly versatile RFID research area.

Passive UHF RFID technology could detect problems with orthopedic fixators early.

On-metal Tag Design

Following the trends of previous years, several papers have been published on developing tags specifically for tagging metallic objects.

Passive RFID sensors

Batterylessness is highly popular when it comes to passive RFID sensors.

Ancient findings and artifacts from ancient city.
RFID sensors could be used to monitor the microclimatic conditions in a museum

Coupling Effects

The following studies indicate that understanding and optimizing coupling effects are crucial for enhancing RFID tag performance in various applications.

RFID Applications

Papers examining RFID applications are, not surprisingly, a rising research area.

Conclusions

In conclusion, the RFID research published in 2023 demonstrates significant advancements in various fields, including healthcare, pharmaceuticals, and intelligent transportation systems. These studies highlight the expanding applications of RFID technology, from improving medical diagnostics and monitoring to enhancing the efficiency of industrial processes and urban infrastructure. The ongoing innovation and diversification in RFID applications underscore the technology’s growing impact and potential for future developments.

About the author

46Bill Hsieh

I am a Technical Support Engineer at Voyantic, with over 12 years of experience in RFID technology, including both HF and UHF applications. I specialize in helping customers troubleshoot issues with our products and providing timely support to ensure their operations run smoothly. My role also involves conducting product training and guiding customers in using our solutions effectively.

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RAIN on Metal – How to Test the Performance of RAIN RFID Tag on Metal Plate

May 31, 2024

Although RFID and metal can be a challenging combination, tagging metal items with RAIN RFID will work as well as any other application, if you choose the right kind of tag designed for metal, and also plan the system and infrastructure carefully. On-metal tags are commonly used in industrial settings, where they need to endure harsh conditions and have reliable performance and readability. It’s great to see how the rapid development in specialty tags helps RAIN RFID usage expand in industries outside of retail. 

We often get asked for advice on testing tags on metal and other materials. So I decided to make an application note on how you can use Tagformance Pro to measure an on-metal tag attached to a metal plate, both inside and outside an anechoic chamber. I will also discuss the impact of the measurement environment on this application. The interesting question is to see how the performance of the tag change when attached to a metal plate, and how much the form factor of the metal plate has an effect.

In the tests, I used the Voyantic Tagformance Pro system and tested Confidex Silverline Blade printable on-metal labels with four different size metal plates.

The confidex tag used for testing

Download the Application Note for the Results and Method

To see the full measurement results and learn how I conducted the measurements, download the application note:

Download the Application Note

Key Findings

To intrigue your interest in taking a closer look at the application note, let me share some findings:

An on-metal tag on a metal plate is highly sensitive to the testing environment, especially outside of the chamber with external RF interference. Testing in an anechoic chamber is thus something I highly recommend for consistency in results.

What do you think? Are these results measured inside or outside of the C50 chamber?

Secondly, the size and shape of the metal has effects on the performance, thus making tagged-item testing a recommendable step for any metal item tagging project.

Setup for testing outside of the anechoic chamber.

Let us know if you have any questions about the application note or using Tagformance Pro for tag and tagged-item testing. We’re always happy to help.

About the author

51Antti Paukkunen

I'm a long-term Voyantician and an Engineering Fellow at the Company focusing on RFID technology and testing methods. Before joining Voyantic in 2011, I was working at Aalto University as a researcher in the field of Applied electronics and Biomedical engineering.

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EPC Gen2 UHF RFID Standard v3 – What’s Changed and Tips for Hands-on Testing

Mar 04, 2024

EPC Gen2 UHF RFID standard v3 update was recently published by GS1. The new version came with optimizations in the air interface and new commands aiming at saving time, improving accuracy, and making the inventory process more robust. In this blog, we’ll walk through some of the most significant changes in terms of inventory performance, and provide pointers on how to get started with testing and learning yourself.

More time (and power) for the chip initialization

The minimum carrier time before the first command has been increased from 1500us to 2500us. The change comes with a small compromise on total initialization time but also works for the benefit of chips which require more time to initialize. The delay is likely small enough to go unnoticed in most applications and the extra time should secure the proper initialization of all chips. Moreover, interrogator power-up is required to be faster (500us → 250us) with more allowance for undershoot and overshoot (+/-5% → -10/+20%) during the 1ms waveform settling period. The shorter rise time is unlikely to influence chip performance significantly and the greater allowance for overshoot opens up an interesting possibility to provide a short carrier level boost (1.58dB/1ms) as part of the field initialization. This kind of boost won’t change the active state operating voltage of the chip but might help them to further optimize their performance during initialization process, and ensure optimal performance of tags.

Fig. Interrogator power-up is required to be faster, but field strength is allowed to undershoot/overshoot by -10%/+20% during the 1ms waveform settling period. The total time before command was increased to 2,5ms. Source: https://ref.gs1.org/standards/gen2/3.0.0/

Field-strength adjustment filters out fringe tags

The third update on the air interface is to allow interrogators to perform field strength adjustment during Select, Challenge, Query, or QueryX commands in an attempt to prevent ghosting tags from slowing down the inventory process. Ghosting tags, also referred to as fringe tags, are tags that have such a low operating voltage, that they might get activated and respond to Query, but do not have enough energy to follow through the response to Acknowledge command. Such tags cannot be inventoried, but since they will reply to Queries, more iterations are required in the inventory process, and the time to complete the inventory cycle gets increased.

The interrogator performs the field adjustment by dropping the carrier level by 0-20% (0-1,93dB) for the duration of the command modulation. The level is adjusted down at least 500us (RF Adjust lead time) before the start of command and brought back up monotonically at the end of the command. Tags are required to tolerate such a waveform pattern and guarantee that the minimum power needed to complete the response to Acknowledge is not more than 1,93dB higher than the power needed to start replying to QueryX. In effect, with the field adjustment in use, the tags shouldn’t have enough power to respond to the adjusted Query/QueryX command unless they’re capable of replying to Acknowledge as well, which reduces the unnecessary overhead from the inventory process.

Fig. Field-adjust before Query/QueryX (upper) and after Query/QueryX/QyeryY (lower). Field-strength adjustment can be used to bring Query sensitivity closer to Ack sensitivity which may help reduce ghosting tags and improve inventory efficiency through the reduction of unnecessary iterations. Source: https://ref.gs1.org/standards/gen2/3.0.0/

New commands further improve filtering and allow simpler memory access

QueryX and QueryY, combine classic Select + Query commands in a single timed package. Unlike Select(s)+Query, they’re effectively packaging the whole series of Selects and the following Query into a single command frame. This blocks external readers from interfering with the filtering process and makes the inventory process more robust. It also prevents tags from participating if they only heard part of the QueryX/QueryY command frame. This could be the case if they’ve been moving in/out of the reader’s field of view during the inventory cycle. Lastly, the new commands come with optional configurations such as an option to choose whether the tag shall include EPC or TID into the ACK response (AckData), whether RN16 is protected with a checksum (ReplyCRC), and flexible filtering conditions: ≥, ≤, ≠, = (Comp). These parameters add flexibility to the inventory process and can be used to make the process more efficient.

Fig. QueryX/QueryY commands effectively package Select(s) + Query into a single command and provide new parameters for more efficient and robust inventory process. (click to enlarge image). Source: https://ref.gs1.org/standards/gen2/3.0.0/

ReadVar, is an alternative to Read (which also remains mandatory in the standard). The two are very close to each other, but the tag reply to ReadVar contains additional informative data. NumWords indicates number of words returned as part of the reply, MoreWords indicates the amount of data yet available in the memory to read beyond the read space, and there’s a parity bit computed over data transmitted (Parity). Overall, ReadVar command is more flexible in comparison to Read and makes tag memory access easier as the user doesn’t need to know the available memory size of the bank targeted.

Fig. ReadVar is a more flexible version of the classic Read command.
Source: https://ref.gs1.org/standards/gen2/3.0.0/

Use custom commands to test new protocol features

Tagformance Pro comes with an option to utilize user-defined custom commands in tag performance tests providing a practical means for testing some of the new Gen2 v3 features. Custom commands can be created using a standard text editor, imported to the software, and used in the performance test programs. For example, it’s possible to generate a custom Query command waveform with field adjustment and testing the effect on tag performance using Threshold sweep (see figures below). Furthermore, a custom command can also be combined with ISO 18000-63 inventory into a custom command sequence, which allows preparing e.g., ReadVar test command.

Fig. Custom command feature allows generating used-defined command waveforms which can be utilized in standard test programs, such as Threshold sweep. (Left) Normal Query waveform Query, (right) Query with field-strength adjustment and 500us RF adjust lead time.
Fig. Measurement example – Query threshold with and without field adjustment. Read sensitivity threshold provided as a reference to give an idea of difference of Query vs. Query+Ack sensitivities of the tag tested.

For more information on the updates discussed in this article and other important changes in the protocol, go to the new version of the protocol on GS1 official website. Of particular interest might also be Snapshot sensor reading procedures which were mainly mirrored from ISO-18000-63. Also, remember to check what’s new in the Tag data standard to stay current with the latest changes in the tag encoding.

Download – Example Custom Command Package ›

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About the author

42Anirudh Wali

I am a Senior Product Manager, passionate about leveraging technology to drive innovation and solve complex challenges in the RFID industry. With a customer-centric approach, I lead cross-functional teams to deliver cutting-edge solutions that exceed market expectations

Content

Lot Management in RFID Tag Production – Essential Machine Requirements

Feb 08, 2024

Over the past few years, Voyantic has successfully implemented the Tagsurance 3 quality control system across multiple RFID tag production lines. These integrations not only enable the highest standards in tag manufacturing but also shed light on the positive advancements within the RFID industry. One notable development is the growing synergy between lot management and quality control. For an RFID production manager or quality manager, understanding the quantity of perfectly functioning tags in a delivery is far more meaningful than just having a count and yield percentage.

Incorporating lot management is more straightforward and cost-effective when done in conjunction with the purchase of new production machinery, rather than attempting to implement it post-machine deployment on the factory floor.

What is lot management? 

Lot management revolves around the concept of a known quantity of deliverables from a specific process step. In the realm of RFID label production, a lot typically corresponds to one roll of labels.

A closely related term is “job.” A job refers to an operation dedicated to producing a specific type of product for a customer or an internal order. Importantly, the process and output remain consistent throughout a job, which may encompass one or multiple lots.

The terminology is easiest to explain with some pictures.

Relation of a lot to an order from a customer, and a job in production.
A lot is typically the same as a roll.

Before starting a job in the Tagsurance GUI, it is possible to define the lot. The lot definition includes details such as.

  • Are all tags counted, or just the good ones? 
  • Is counting across lanes, or on a single lane? 
  • Is the lot change marked with a cut mark?
  • What should the machine do when the lot is complete?

Lot management

In a typical production setup, where delivery and production are roll-based, lot management includes:

  • Producing rolls with the desired quantity of labels,
  • Understanding the quantity of tags within each roll, and
  • Generating and reporting relevant data for each lot (each roll)

Tagsurance 3 system role in lot management

Tagsurance 3 quality control system plays a pivotal role in the seamless lot management in RFID tag manufacturing. It employs a sophisticated approach to decide whether an individual tag should be counted in the production result set, leveraging comprehensive test data to ascertain the number of tags produced on each lane, differentiating between good and failed tags.

One of the distinctive features of the Tagsurance 3 quality control system is its granular understanding of the location of each tag on the production line. It precisely tracks the lane and the distance from a trigger sensor in millimeters, providing essential position information. This combination of counts and position data serves as the cornerstone for effective lot management.

Given that the Tagsurance 3 quality control system possesses a wealth of information, it becomes the logical and secure choice to entrust with lot management. An alternative approach could involve transmitting count and fail status information to other machine components, such as the machine PLC. However, this introduces unnecessary complexity and potential risks. In high-speed production lines, even a minimal delay in data transmission (from Tagsurance 3 to machine PLC) carries the risk of misaligning counts by a single tag.

The optimal and most efficient solution is allowing the Tagsurance 3 quality control system to take charge of lot management for the following reasons:

  1. Precise Quantity Tracking: Tagsurance 3 is equipped to accurately determine the number of tags in a roll.
  2. Comprehensive Reporting: Tagsurance 3 generates and reports relevant data for each lot, providing a comprehensive overview of passed or failed tags.

When the Tagsurance 3 system manages the production lot information, the risk of split-brain problems between different systems is eliminated. Additionally, Tagsurance 3 offers the flexibility to provide precisely timed signals before, on, or after lot completion, ensuring a smooth and synchronized production process. This level of integration not only enhances operational efficiency but also mitigates the potential risks associated with data transmission delays in a fast-paced manufacturing environment.

Cut mark

The cut mark serves as a practical tool in lot management, providing a visual demarcation between the end of one lot and the commencement of the next.

Cut marks indicated in Tagsurance 3.

Tagsurance 3 system seamlessly integrates with the manufacturing process, triggering the device responsible for creating cut marks. In many instances, the same device used for marking failed tags is employed for printing cut marks as well.

What does the machine need to handle?

While the Tagsurance 3 system handles various aspects of lot management, the tag manufacturing machine still plays a critical role, particularly in the precise execution of cutting tasks to create the desired rolls.

There are different ways to do this: 

  1. Automatic turret rewinders 

Some machines incorporate automatic turret rewinders, presenting an efficient solution. In this setup, the production job operates continuously, and rolls are automatically cut to the correct size. This automation eliminates the need for manual roll changes by operators.

  1. Cut mark and manual cutting

In certain scenarios, manual or semi-manual cutting methods prove to be a better alternative. Safety considerations often drive this choice, as automatic cutters need to be well-shielded for the safety ofrom human operators.

In a manual or semi-manual process, the machine halts when the liner reaches the cut position, such as at a splicing table. The operator then manually cuts the liner before seamlessly continuing the process with a new output roll.

https://youtu.be/1M4SVh5I2OU?si=VT3-2XRcrJmjzk50&t=12
This video shows an example of a Turret Rewinder by GM where, at the end of a lot, the machine first slows down and stops, and then an operator cuts the web and finally restarts the machine.

Selecting the appropriate cutting method depends on factors such as safety requirements and the layout of the roll handling area. Whether through automated turret rewinders or manual cutting processes, the tag manufacturing machine’s role in achieving precision and efficiency ensures the delivery of high-quality RFID tags.

Must-have machine features for seamless integration

One indispensable feature that facilitates the seamless integration of lot management with automated testing solutions is a digital IO (Input/Output) input, acting as a control mechanism for the manufacturing machine.

Stop signal input

For efficient lot management, there is a need for precise and controlled stopping mechanisms. Particularly in high-speed machines, abruptly halting operations may compromise accuracy, leading to challenges such as incorrect cutting positions on automatic turret rewinders or misalignment at the splicing table. The inclusion of a digital IO input allows for a controlled cessation of the machine, ensuring accuracy and reliability in the manufacturing process.

Slow down signal input

In practical terms, high-speed machines benefit from a gradual slowing down process before coming to a complete stop. This gradual deceleration is vital for intricate operations, such as ensuring precise cutting positions or accurate alignment at various stages of production. The machine’s ability to receive a digital IO input for initiating the slowdown process enhances the overall control and precision of the manufacturing workflow.

The machine slows down before stopping.

Serial port interface alternative for stop and slow down signals

While digital IO inputs serve as the standard for most machines, it’s worth noting exceptions, such as the utilization of a serial port interface in certain models like the Muhlbauer DDA machines. However, in general, the industry standard leans towards the effectiveness of digital IO inputs for optimal control and coordination between lot management and quality control systems.

Nice-to-have machine features for improved efficiency

Two features that significantly contribute to this efficiency are Cut Mark Capability and Operator Signal Integration.

Cut mark capability

Having a discernible cut mark on labels proves invaluable for human operators, especially when machine stopping accuracy is not within a few millimeters. This visual indicator aids operators in clearly identifying which labels belong to the previous lot and which are part of the next one. Even with automatic turret rewinders, the presence of a cut mark provides operators with peace of mind regarding the correctness of quantities.

The Tagsurance 3 system excels in this aspect, precisely triggering the cut mark at the right position. This feature not only enhances accuracy but also empowers operators with a clear demarcation between lots, ensuring seamless continuity in the production process.

Operator signal

Efficient lot management extends beyond just machine capabilities; it involves effective communication with operators. Even in the case of automatic turret rewinders or manual cutting scenarios, alerting operators when a lot is nearing completion proves invaluable. This proactive approach allows operators to prepare for tasks such as cutting the liner and changing the roll promptly, minimizing machine downtime.

The Tagsurance 3 system takes the lead by providing timely signals, either on lot completion or even a predetermined quantity before completion (e.g., 500 labels before the lot concludes). These signals can be utilized by the machine to trigger visual alerts, such as signal lights, or audible notifications through loudspeakers. This integrated communication ensures that operators are well-informed and can take prompt action, contributing to a more streamlined and efficient RFID tag manufacturing process.

Signal lights alert the machine operator.

Strategic considerations for a label manufacturer to optimize lot management

The seemingly minor features within the production machinery play a pivotal role in the seamless execution of lot management. Features such as

  • slow down signal input,
  • stop signal input,
  • serial port interface on some Muhlbauer DDA machines,
  • ability to print cut marks and,
  • ability to signal the operator

might appear subtle, but their absence can pose challenges in implementing effective lot management.

When investing in a new label manufacturing machine, ensure that lot management-related details are explicitly specified. The absence of connectors and signaling means can prevent lot management from working optimally. As RFID technology evolves, these features become indispensable for RFID production and quality managers seeking to elevate standards and achieve greater efficiency in the tag manufacturing process.

Connect with us to learn more about Tagsurance 3 lot management features and integration into production machines.

Request a Tagsurance 3 Demo

About the author

21Jesse Tuominen

I joined Voyantic as a partner in 2005 to design Voyantic's first commercial product, and I've had a front-row seat since then to see how the RAIN technology has evolved and matured while bringing my own contribution to it. As a background, I have a MSc level in electronics after which I made my PhD in the field of photonics. UHF RFID slots nicely between these two worlds and they offer a lot of perspective into my work. Currently, as the CTO of RFID technology, I work with new measurement methods, RF design, proofs of concept, standards, protocols, industry collaboration and IPR.

Content

RAIN RFID Tag ICs – The Road to Configuration Words

Nov 21, 2023

Tag config memory –  What is that? Is it a fifth memory bank? Having configuration words in tag memory is the new normal in the industry and it is slowly gaining importance and cannot be ignored any longer. How did we end up with config words and how can we embrace them instead? Let’s take a look.  

Birth of Gen2

The core features and the operating principles of a RAIN tag IC have remained the same since the birth of the protocol in 2004 – The ability to wirelessly read and write memory contents, the ability to lock all or parts of the content from further edits by outsiders, and the ability to permanently disable the transponder when it has served its purpose.  That was pretty much it and to a great extent, still is.

The memory was organized into four parts all with their special purpose. Also, in the air interface protocol, a total of two bits were reserved to specify which memory was to be selected, read, written, or locked.

Memory bank 00 is the “reserved memory” and it contains the 32-bit Kill password as its two first words and the 32-bit Access password for the following two words, four 16-bit words in total.

Memory bank 01 is the “EPC memory”. This is where the EPC code is stored. EPC code is the specified part and length of the memory that will be broadcasted in the inventory process. The two first words in the EPC code have a special function. The very first word has a precalculated error correction word, CRC, stored in it. The second word, referred to as the protocol control word, or PC-word, is an important one. It is a word broadcasted prior to the EPC code in inventory and has several single-bit flags to tell which features tag has activated, and what numbering system it might belong to. It also has a 5-bit L parameter to tell and set the length of the broadcasted part of the EPC code. In short, in the inventory process, the tag would give a reply consisting of PC+EPC+CRC all from this memory.

Memory bank 10 is the “TID memory”. This has all the unalterable records of the tag locked from the factory in the wafer state. In particular, it has MDID specifying the company that designed the IC and TMN specifying the exact IC type and version.

Memory bank 11, is the “user memory”. This is a memory dedicated for the user to write any other entries the application needs, and should contain no special words or bits for the protocol or IC operation. As only a few applications require this type of “disc space” and most applications work solely around the EPC code, most commodity tags don’t actually have any user memory. Manufacturing expensive non-volatile memory “just in case” is too expensive as it uses quite a lot of  IC surface area.

Typical memory map and memory contents of the four memory banks when read with Tagformance Memory Management tool. The MDID+TMN reveal that this is the memory of a tag equipped with an older monza5 chip .

Rise and fall of the custom commands

Very soon after the very first wave of ICs had hit the market, the second wave of ICs from roughly 2010 and onward had several new features that were not considered in the original memory organization and protocol. However, the protocol had large RFU provisions for custom commands. So, each tag IC got their own set of special vendor and IC-specific commands to activate and control the new advanced features. The tag features were often clearly documented in datasheets and worked well. However, readers, their command sets, and UIs really struggled to keep up with new and specific firmware versions often needed. For practical matters, like controlling the privacy level of retail tags in this somewhat custom and vendor-specific way just didn’t work too well.

Gen2v2 to the rescue

In 2014, the protocol got a new version, the Gen2v2, which included many of the features added earlier as custom in a somewhat more standard way. The main topics that the new version touched were authentication, encryption, and user privileges. This cleaned the table a little, but still, using new commands to access new features was already found to not always be the easiest solution to adopt.

Configuration words

What happened nearly simultaneously with the release of Gen2v2 was that the control of these added features was slowly transferring from specific new commands to standard Select, Read, and Write commands just pointing to special memory locations. Every reader and reader UI already had filters and memory read functions enabled, so these could be “misused” to control tag settings. Specially formulated Select commands were used to trigger events like “record sensor reading” and “switch to temporary operating mode X”. Writing specific control bits changed settings like tag memory allocations and backscatter levels the state of which could be retained in memory from this point on and to be retained through power cycles.

Soon every manufacturer had their own “config memory bank” or “config word” hidden deep inside the already existing four banks with bits and parameters to be configured to tailor the tag functionality.  The trouble was that each IC manufacturer placed the config memory in a different place with varying functionality. Also changing the settings is not always as easy as hailing the tag and writing, as special safety measures are often set in place.

In hindsight, It would have been great to have had a 5th memory bank for tag settings, but as there were just the two bits in each command to specify the memory bank, we were already kind of maxed out at four.

Vendor-specific implementations

Impinj

From roughly the R6 family onwards, Impinj has chosen to place the config word in the reserved memory bank, right after the two passwords at address 0x04. This location has been kept throughout the various R6, M700, and M800 families of ICs with the purpose of each bit being kept more or less similar. Some of the features that can be configured are read range reduction, autotune disable, unkillable mode, and memory split between EPC and User memories, and some inventory optimization modes. More complex ICs like the Monza X-8K have used several words deeper in the same reserved bank for even more settings. Care must be taken when setting the features as only some of the bits can be written, some need to be written from a secured state with a non-zero access password and some bits can only ever be changed once. As the protocol only allows full 16-bit words to be written, changing single bits needs to be done with care and optimally the whole config set on one single write event.

A common reason for changing tag configuration is to trade some of the maximum EPC length into user memory. For instance, the only difference between the M830 and M850 is a different split between the EPC and user memory sizes, and the swap can also be made through the tag configuration bits.

NXP

NXP on the other hand has chosen to primarily use the word at a word address 0x20 in the EPC memory for configuration starting form the Ucode G2iL family of ICs and through the G2iM, Ucode 7, Ucode 8, and Ucode 9. Available features vary from model to model, some of them touching on the topics of product flags, backscatter strength and curve type,  parallel encoding, memory config selection, write power indicator, self-adjust settings, and memory checks. Some of the bits are action bits, meaning that selecting on those will trigger special features, some bits are permanent bits for configuring more permanent modes and some are purely indicator bits for reading current feature status. Changing some of the settings is careful work as some require a non-zero access password, then accessing the tag with that, then strictly using a mandatory Write command to perform a toggle-write on the bits that are wanted to be flipped.

NXP Ucode9 has config bits to select from different backscatter responses which can be helpful to optimize for privacy, performance, or conformance.

EM Microelectronic

EM Microelectronic has been known for their “more involved”, more advanced, and therefore also more complicated ICs hosting a variety of features, such as serial data interface, power outputs, sensoring, IO-pins, NFC+RAIN operation, TOTAL tag talks only modes, etc. These advanced settings often take several words of memory space for configuration in what EM refers to as “System memory” at the far end of the User memory bank.

Alien

Alien has a “Device configuration” often further up the TID memory bank. However, not many public datasheets are available describing the functionalities better. Most probably they are settings performed by the manufacturer and are not meant for the user or an encoding process to mess with. Anyhow, so far four manufacturers and four different memory banks have been chosen for config purposes.

Other manufacturers

With several dozens of Gen2 tag IC manufacturers in the game, there are too many to mention and not all distribute proper open datasheets to share all features in public. However, it seems that some of the newer players on the market have chosen to adopt one of the existing strategies, such as the Impinj Reserved memory word 0x04 for a comparable configuration. This might help existing readers support the newcomers when the location of the settings is the same.

Afterthoughts

There are several good aspects on this topic. First of all, for at least 90% of the customers, the initial settings are just fine. Also, with the two biggest RAIN IC providers on the market covering such a large market share, there nearly are two “standard” ways to control tag configurations. Furthermore, the Gen2v3 is just around the corner (more on that later), but it is not going to touch on the subjects typically controlled by the tag config bits. Unfortunate, that it will not clean this up, but then again fortunate, that it will not introduce even more ways to facilitate configurations that are bound to evolve faster than the protocol versions ever will. The place where the spread and complexity of configuring RAIN tags is putting the most pressure is probably in the encoding of tags where each IC type needs to be recognized and catered for to serve the remaining sub 10% of cases. If your software or UI is not recognizing the IC types, then the datasheet is your friend in deciphering the tag configuration options.

A personal plea to all the RAIN IC manufacturers out there: Please keep the datasheets publicly available to your customers and solutions providers. Also, luckily we are today talking about small single-bit differences in tag configs, as RAIN stands technologically relatively united and nowhere near as spread out and as complicated a disorder as the 13.56MHz playground that NFC is trying to unite and clean up. Let’s continue keeping RAIN united.

About the author

15Teemu Ainasoja

I am VP, Marketing and Sales at Voyantic. I have over 15 years of experience from the RFID industry in Europe and the USA. I have two master's degrees: in industrial engineering and in marketing, and two patents in auto-ID technology. I am actively participating in RAIN RFID alliance activities.

Content

Trigger Sensors in RFID Production – Get It Right

Sep 06, 2023

In the past couple of years, I have been following several projects where the Voyantic Tagsurance systems have been integrated into production machines.  Surprisingly often, the biggest problems have been related to triggering – “seeing” accurately when a label enters the system. The experience even turned into a rule of thumb: “If something does not work correctly, first check the triggering”. I have realized that getting the triggering to work correctly is of utmost importance.

At the same time, I have been pleased to see plenty of new Tagsurance features that help to avoid challenges with triggering.  

In this article, I will discuss:

  • Why it is so critical to get triggering to work perfectly?
  • Why triggering can be difficult?
  • How do Tagsurance 3 features help get the triggering reliable?

Principle of Triggering

All (or most?) trigger sensors work with the same few simple principles:

  • Each sensor has a physical parameter it monitors. Depending on the sensor type the parameter can be the strength of light of a certain color (through a beam sensor), amount of conductive material (an inductive sensor), darkness of view (a contrast sensor), darkness and shade of color in view (a color contrast sensor), and so on.
  • The sensor has a window of view.  It only senses the parameter within this window of view.
  • The sensor is trained/programmed to recognize when the parameter passes a threshold value. For example, if a view of a contrast sensor gradually turns from white to light grey to darker greys and black in the end, the sensor is trained to see a specific point in the continuum as the threshold point.
  • At the threshold point the trigger sensor’s digital output changes from 1 to 0 (or vice versa, or the trigger sends a pulse).
A contrast sensor is designed to see the edge between light and dark areas when the edge passes the window of view. In the sample, the labels have a printed trigger mark to make the triggering easy.

Why does triggering need to be perfect?

Any problem in triggering will affect the overall quality system performance, production machine performance, and production process accuracy and efficiency. Some triggering problems are obvious, some are more subtle.

  • Missed triggers
  • Double triggers
  • Not detecting missing labels
  • Suboptimal timing
  • Suboptimal positioning

If a trigger is missed on a tag, that tag flies through the machine undetected. It would not be tested or otherwise processed. It would not be recorded in production logs. It would not be counted to output quantity. But it would be on the roll and get delivered to the customer – free of charge, of unknown quality, and probably incorrectly processed. With a high likelihood, there would be problems awaiting the customer.

A double trigger is an opposite issue. One label is counted twice and attempted to be tested and processed twice. There is a high likelihood that one or both of the process actions fail. The customer would only receive one label instead of the two that were counted.  Counts, log files, yield data, and so on would be incorrect.

In some processes, a label can be detached from the liner. Recognizing these missing labels can be important for keeping the entire process optimal. The challenge is to notice when a label does not pass the trigger sensor when expected. A bit of smartness needs to be added to the trigger signals.

In RFID label production machines, there are usually only a few milliseconds to test an individual tag. Accurate results are based on the inlay being at the right position on top of the test coupling element when the test is made.  

In this example, a label can move 7 mm on top of the Snoop Pro coupling element while being tested. With 60 m/min lane speed, this gives 7 ms of test time. If 1 mm is wasted because of suboptimal or non-consistent triggering, the test time is reduced to 6 ms (about 14.2% less time available).

Why triggering can be difficult?

The root causes for triggering difficulties vary:

  • One sensor type may not fit each produced material.
  • The “edge” may not be clear enough for the sensor in use.
  • There may be multiple edges per inlay at the path crossing the window of view.
  • When the liner moves, it may also drift across the lane, or vibrate up and down.
  • Materials have imperfections.
  • With fast-moving material, it is not easy to see the exact position of triggering – optimization is difficult.

In RFID label machines typical materials to trigger are:

  • Inlays
  • Cut labels
  • Uncut labels
Cut RFID labels

Cut labels are usually the easiest material with clear edges between the label and out of the label.  Triggering issues may arise, for example, if lighting conditions change. Glossy materials would amplify the difficulty. The issue is that the threshold position within the window of view can drift if the sensor receives a variable amount of light. If the color of the liner is close to the color of the label, detecting the edge may not work with a contrast sensor.

Uncut RFID labels. Note also material being wavy, this is a potential problem for accurate triggering.

Uncut labels without a trigger mark cannot be triggered with contrast sensors. Depending on the material a through-beam sensor or metal sensing inductive or capacitive sensor is needed.

Inlays with no single-edge trigger path (multiple edges per label).
(inlay outline from www.tageos.com)

Some inlays (antenna on a transparent liner) may not have a clear trigger path, but the trigger sensor would fire multiple times per inlay. Sometimes the antenna shapes are small compared to the window of view, in this case, even the smallest drift across a lane could be a problem.

Inlays with a clear trigger path (inlay outline from rfid.averydennison.com)

In label machines lane speeds are typically tens of meters per minute and can be even hundreds of meters per minute. At high speeds, materials start easily vibrating. If the material happens to jump when the edge is in the window of view, there is a risk of double trigger.

Voyantic Tagsurance 3 system has several built-in features that help with triggering.

The Tagsurance 3 system has features that help in avoiding typical trigger problems. When used correctly, the Tagsurance triggering is 100% reliable.

Tagsurance 3 Triggering Features

The Tagsurance 3 features that help with triggering include:

  • Support of multiple sensor types
  • Advanced pattern recognition
  • Simulated triggers
  • Visibility on trigger performance
  • Strobe light

Tagsurance 3 Supports Multiple Trigger Types

Several types of trigger sensors can be used in the Tagsurance system. All these sensors are plug-and-play compatible with the Tagsurance system.

  • Contrast sensors (grayscale or color contrast) recognize differences in color or darkness, such as the edge between a liner and a label, as long as there is a contrast difference.
  • Through-beam sensors sense changes in materials’ capability to pass light, as long as some part of the material passes light.
  • Capacitive triggering senses edges between metal and non-metal
  • Ultrasonic triggers sense differences in material thickness
Several trigger sensor types can be used in the Tagsurance 3 system.

Pattern Trigger

Pattern trigger is a feature that can always be used.  Defining a simple pattern has proven to be an efficient way to avoid double triggers regardless of the root cause. It eliminates double triggers arising from complex antenna patterns, varying light conditions, a vibrating liner, and so on.

An example of a simple pattern trigger settings.

The above picture illustrates settings defining a simple pattern. This pattern replaces a plain edge recognition, by expanding the edge. In this pattern, when the label passes the window of view of the trigger sensor, the sensor must first see 3 mm white, and then 2 mm color (trigger mark). When the defined pattern is seen, the trigger is fired at the actual edge position inside the 5 mm long pattern.

This pattern efficiently eliminates double triggers. If the trigger saw 2 edges – for example, because of liner vibrating, the pattern rule would not be met. This is when simulated triggering comes into play.

Simulated Trigger

In the above settings, the repeat length, aka pitch, is defined to be 25.01 mm, and a simulated trigger is generated after 7 mm has passed from the expected trigger position. The following actions are performed at the expected label position (and not 7 mm off).  

The trigger is simulated if the sensor doesn’t fire as expected, regardless of the reason. Reasons for not triggering could be poor-quality printed trigger marks, missing labels, lane drifting, or trigger patterns not matching the set trigger pattern conditions.

The simulated trigger feature fixes most of the issues causing the trigger sensor not to see the edge as expected.

The simulated trigger feature is also used in detecting missing labels.

Hold-off Distance

Another possibility to avoid double triggers is to set a hold-off distance. With this feature, a double trigger is discarded within the hold-off distance. For example, if a 0.5 mm hold-off distance is set, it eliminates most of the double triggers.

Hold-off distance should be used with caution when used to avoid double triggers in complex inlays.

Use hold-off distance with caution. In the example, an inlay is normally triggered on the first edge, and triggering on the second edge is avoided by setting a hold-off distance (1). But, if a trigger is missed (2), the triggering will permanently go off sync (3).

Visibility into Triggering

Tagsurance 3 system provides visibility on trigger reliability.  The trigger sensor view shows the actual repeat length as seen by the trigger sensor.

Trigger sensor view

In the above example, there is periodically one repeat that is about 0.5 mm longer than others. This 0.5 mm must be considered when optimizing the trigger position. An additional 0.5 mm safety margin must be used.

Trigger sensor view – missing label

In this example, the liner drifted and for a short period, triggers were missed. The scale of the repeat length changes for a while because of the exceptionally long trigger interval. Similarly, double triggers would be observed as exceptionally short trigger intervals.

Strobe Light

For optimizing trigger position Voyantic offers a strobe light that automatically synchronizes with trigger signals. The strobe light flashes whenever a label is in the test position. And because the human eye works as the human eye works, the strobe light shows perfectly where the label is on the coupling element when testing starts.  Optimizing trigger positioning becomes easy.

When the trigger position is adjusted in the GUI, the trigger mark shift can be observed with the help of the strobe light. (Note that the video with frame rate limitations does not do justice to the strobe light, the real-life view is even better)

Recommendations – How to Make Triggering Perfect

  1. Select a sensor type that matches the material.
  2. Use the pattern trigger feature combined with simulated triggering.
  3. Confirm reliable triggering with the trigger sensor view.
  4. Use strobe light to fine-tune the trigger position.

With the above principles, the trigger sensor will work perfectly.

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About the author

32Voyantic Marketing

Content

Why Label RF Quality Matters – Excellence in RFID

Aug 23, 2023

Summary

  • Bad RFID tag production quality = unacceptable variance in tags’ sensitivity = inconsistent performance / read ranges = unreliable RFID system performance = unhappy customers = bad for business
  • Quality can only be checked with professional RFID testing and quality control systems
  • Voyantic can help you improve design and manufacturing quality

Voyantic has published a lot of content about RFID technology, the market, and quality testing practicalities. But I wanted to understand what quality really means in RFID. And why should label converters and tag manufacturers care? Read on to find out what I learned.

Framework of RFID Tag Quality

The quality of RFID tags and labels boils down to RF performance – how consistent is the performance compared to the RFID tag specifications? RF quality cannot be seen with the human eye. Nor can the RF performance of a smart label or inlay be checked with any camera, x-ray, or machine vision. The quality can only be checked with RF (radio frequency) measurement system.

(Note: The other aspect of RFID tag quality, that will not be covered in this post, is tag data content. Learn more about tag data and encoding here: https://landing.voyantic.com/webinar-rain-rfid-encoding-for-barcode-professionals)

With that in mind, the following framework describes the levels of defining smart label RF quality, from design quality to documented production quality control: 

  1. Design Quality means fit-for-purpose
    RFID tags are designed for different use cases and applications. Good quality design means that the tag has the required performance and durability for the intended use case, taking form factor and unit cost into consideration as well. In practice, performance translates into readability and read range of the tag in the environment it was designed for: from how far the tag can be read, and from which angles, what type of items is it a good fit for?
  2. Tags can be functional but not-fit-for-purpose
    Taking a simple approach, the functionality of the tag can be checked with any reader – if the tag ID can be read, it is a functional tag. Sadly, this approach does not reveal aspects of quality, or if the tag meets the requirements or not.

    Consider an analogy to a tag functionality test from the automotive sector: at the end of a car factory line, someone only looks at and listens to the cars: “I see a car and hear the engine – Quality check ok!”
  3. RFID tester verifies that tags meet the specifications 
    A proper quality test measures the RF performance of the tag, preferably on the production line. Voyantic’s Tagsurance 3 RFID production quality control system checks the tags’ performance against pre-set criteria. The system gives a pass/fail result based on the requirements for each RFID tag passing through the system. 
  4. Knowing the production variance is the key to improving your process
    Quality testing also reveals the variance in the tested tags’ performance. The variation in the tags’ sensitivity in practice means the differences in the tags’ read range. Tag sensitivity is the measure of how much power is needed to wake up a tag. Variance is inherent to mass production – manufactured tags are never perfectly identical. Quality requirements set the acceptable variance limits for the tags’ sensitivity, ensuring they meet requirements for consistent performance, i.e., consistent readability of the tags.

    Knowing the variance is essential for internal development: for discovering good practices, and making comparisons – comparing machines, production teams, materials, settings, and so on.
  5. Customers expect proof of quality
    The highest level is to be able to prove the quality in detail. A professional quality control solution automatically records a log of all tests with the tag’s unique codes along the log data. This record can be used to prove the quality of the production batch and to prove the quality of each individual tag.
Testing in RFID inlay and label production is required to verify the produced tags meet the designed sensitivity.

Why Quality Matters…

…for the RFID system end-users?

Variation in sensitivity causes the readability of the tags to vary. Differences in tags’ read ranges lead to missed readings, and ultimately, decreased reliability of the whole RFID system.  High variation in tag sensitivity also indicates variation in durability – some tags may last longer than others. End users will not be happy to see the reliability of the RFID system decrease.

Customers expect consistency and for each tag to perform according to its datasheet information. As customers’ knowledge and experience of RFID technology increases, they also expect a documented quality program and, in some cases, require documented proof of quality from the tag supplier, and even compliance with a quality standard. 

…for manufacturing?

Quality management is the bedrock of RFID inlay and label manufacturing. A complete RFID quality control system gives visibility into the production process to catch production line issues early on before more tags start to fail, thus reducing waste and improving yield. 

The statistical quality data also enables comparing machines, production lines, and shifts. Good practices can be adopted, and poor performance can be addressed, improving the overall efficiency of production.

… for management?

A company’s top management typically focuses on the long-term growth and profitability of the company. High-quality products contribute to customer satisfaction, thus helping to drive more recurring sales revenue. Higher production yields, reduced waste, and increased production efficiency also contribute to better margins.  

The measured quality data is the basis for continuous operational improvements and long-term profitability. In practice, data enables optimizing investments: Which machines and materials work the best, and where there is room for improvement?

The Cost of Bad Quality

As the industrial scale of a company increases, the importance of good quality and reliability gets to a whole new level. Two very typical use cases for RFID are inventory tracking and supply chain management. Big brands and retailers may have hundreds of millions of items tracked and traced with RAIN RFID throughout their supply chain and retailer networks. If you consider, for example, that 1 percent of the RFID tags used to track items do not work well, that doesn’t initially sound too bad. But when you are tracking hundreds of millions of items, 1 percent translates into millions of products being lost from inventory tracking and considered stolen, wasted, or otherwise unaccounted for. 

The Experts in RFID Testing and Quality Control

Voyantic’s core business is to measure the performance of RFID tags and inlays – to help our customers make sure every delivered tag works right, and enable engineers to make better products. Our vision is that every RFID tag and label have been tested and verified in the production process with our quality control system

Get in touch to see if we can help you with your RFID projects!

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