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tagman
New Member
12 Posts |
 Posted - 01/25/2004 : 09:49:31
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| Ive seen lots of information about being able to read these passive tags over great distances - I've seen about 5m mentioned. Is this really possible in practice? |
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steveheap
Average Member
220 Posts |
Posted - 01/26/2004 : 15:05:38
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The information I have seen of real installations, suggests that a reading distance of around 2m is realistic in practice - the particular report that I am thinking of was of a warehouse environment, and the report went through tests with multiple vendors - Matrics, Alien, Intermec and identified the issues and the solutions they came up with. There are two reports in the "white papers" part of this site - search for "RFID test" - but the one that explains the above can be found at: http://www.buyrfid.com/rfidwizards/docs/tests/rfid_test_results_warehouse.pdf
Hope this helps
Steve |
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tagman
New Member
12 Posts |
Posted - 01/26/2004 : 15:34:54
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Steve
thanks - i checked out the paper - there is a lot of useful information in there. It is a pretty complete list of real issues that we will face in getting the system to work. |
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Hagan
Starting Member
8 Posts |
Posted - 02/12/2004 : 14:32:40
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First of all, you need to determine what frequency you are emitting at. There is a definite bell curve when it comes to read range and frequency- and many different curves when it comes to applicability. At 13.56 MHz, you get natural noise from all around (mainly the sun) that gives you a read range of about 2-3 feet max, and barely any motion detection. It is just difficult to get any passive backscatter energy from 13.56 because you have to use the near field for interrogation purposes (way too much resistance in a half wavelength antenna). However, in certain applications, 13.56 MHz is extremely useful. At 433 MHz and 915 MHz, you can start producing more results in the asset tracking realm, because you can interrogate tags moving at decent speed (faster than a person can run at 915) and don't get much antenna loss. At 2.4 GHz, you can't produce enough power to get a read range more than a foot, unless you incorporate some kind of active tag system. (well you can produce enough power, technically, but you'd better hope the FCC doesn't find you). Read range/applicability depends on the goal, the environment, and the price your willing to pay. For all intents and purposes 433 MHz-915 MHz gives you the best read range under normal environmental conditions (i.e. not a lot of moisture during the daytime), but lower bands and upper bands definitely have their place in integrated RFID systems for a multitude of reasons.
Hagan
ODIN technologies
www.odintechnologies.com |
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steveheap
Average Member
220 Posts |
Posted - 02/12/2004 : 16:43:49
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Hagan
Thanks for the info - very helpful!
Does ODIN have any information to back up the tests that were documented in the earlier post? The questions about the EPC generation of tags, and the readability of those at the 10 foot range, seems to generate the most interest. Have you tested such tags yourselves? I see you have a test lab in operation.
Steve |
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kevinchung
Starting Member
5 Posts |
Posted - 02/12/2004 : 17:57:40
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We would like to post contrarian data for the 13.56 MHz RFID system.
We have extensive experience with different ways to make RFID tags with more read distance for a simple loop antenna. We found the common wisdom to be far from the truth.
For a simple loop antenna at 13.56 MHz @ less than 4W, most of the commercially available tags using silver epoxy bonded on copper or mechanical crimping on aluminum inlay antenna traces, with tag form factor or 2"x3", the read distance are indeed 2 feet in the best condition. Of course, one would expect the read distance to increase somewhat if the tag form factor increase to 4"x4" like that of Matrics tag. We do not have such size tag or data.
Using a copper inlay antenna and soldered interconnection between chip and inlay, for the same form factor of 2"x3", the read distance of 3 feet and more is standard. With 4"x4" tags, the read distance increase to 4-5 feet.
If we optimize the antenna with a patent-pending technology from AVANTE, the same tags at 4"x4", the read distance at the same power reaches 5 feet or more. For a slightly larger than of 5"x5", the read distance reaches 6 feet and more. We are able to construct a portal for these size tags to be track with 100% accuracy in all orientation (not including orientation with tag facing the ground) and position within the portal space of 8 feet wide and 7 feet height. Only two antenna arrays are used. Orientation facing the ground can be covered with anothe set of antennae if desirable.
As for the speed of read, we have a test performed under the auspices of FAA, within the conveyer portal of 42 inch width and approximately 4 feet height, 100% accurate read rate were achieved for tags of approximately 2"x5" that fit the standard airline tag at a speed of 8 feet per second. This is approximately 6 time faster than 1.5 feet used to test the 915 MHz. This test was performed with tags placed on common bags including metal (tag is attached so that it hanged outside). The orientations include all 3 dimension. That is, it also include the orientation facing the ground.
One thing that most people forget and never mention is the effect of weather. It is well known scientifically that 915 MHz tags may be totally blinded under condensing environment such as rainy or snowy day. Are we going to use barcode instead in such days?
By contrast, the read distance efficiency at 13.56 MHz under such condition, we only measure a loss of less than 20%. The same tags of 4-5 inch square are still effectively covered with 100% read rate.
AVANTE is located in Princeton Junction, NJ. We can arrange a group demonstration to all those that are interested to those tests that we mentioned above. The FAA report is available upon request.
Sincerely yours,
Kevin Chung, Ph.D., kchung@aitechnology.com
AVANTE International Technology, Inc.
www.avantetech.com |
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Tom Napier
Starting Member
6 Posts |
Posted - 02/13/2004 : 10:20:11
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Hi Kevin,
Do your Avante tags conform to the ISO 15693 standard? You are getting an excellent read range w/ 4w antennae. I am very interested in getting further infomation from you.
Please email your white paper(s) to me.
Thanks,
Tom Napier, R.Moroz Ltd. (tomn@rmoroz.com)
Tom Napier, R.Moroz Ltd.
www.RFIDCanada.com |
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Hagan
Starting Member
8 Posts |
Posted - 02/13/2004 : 11:45:16
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Those are impressive results for 13.56 MHz- and exciting news. I'd like to remind you though Kevin, while you maintain that atmospheric conditions reduce the interrogation capacity of 915 MHz, they also reduce the interrogation capacity of 13.56 MHz. Sunspots 93 million miles away affect 13.56MHz. Through spectrum analysis, one can see how much lower band noise is present during the day from natural sources, and especially from artifical sources like 3 phase warehouse power. (I'll admit that residential DC power running through a model train track, with simple stainless steel track placed 5 feet from a Tyco closed-loop antennae, using a reader from company X (wish I could say- sorry) reduced the read range to a few inches... previously from 2 feet). I'm impressed that your tags were read at such speeds, at 100% accuracy, in any orientation, but was concerned with increasing size of the tag. Unfortunately, the larger the tag, the more the material, the higher the price- and the more difficult it is to use. You used it for airport conveyors- was the object the tag was affixed of constant shape- I'd imagine it would get a lot of wear and tear if it was on a lose bag- or was it covered by a hard container. Like our RF engineer, I am pretty hardware agnostic so I am critical of a lot of new hardware (but am extremely curious). Manipulating the RF environment around the antennae/reader seems to be the answer to reading tags- and it also seems to be the most cost effective solution. The key to RFID is not making the most readable tag, but, unfortunately for all purely-scientific minds, creating the most economical solution. That is basically what my company does- we find the most economical solution for integration based on the comapnies specifications. Most data is useless, until the overall system architecture of a site is known. ODIN has patent pending software coming out which will reduce the time needed to analyze sites by orders of magnitude.
Kevin, I am extremely interested in this new tag- it would be a breakthrough if it were durable. I'll tell everyone right now- many tags from the top 5 tag vendors are breaking right now- tested it with a directional coupler and they just don't create backscatter- this could be a potentially HUGE problem for RFID's reputation.
Hagan
ODIN technologies
www.odintechnologies.com |
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Hagan
Starting Member
8 Posts |
Posted - 02/13/2004 : 12:00:19
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Steve,
Hi. We do have a lab for testing, but one must always remember, a lab for RFID does not do everything in terms of experimentation. It is absolutely VITAL that experimentation be done on site because the infinite possibilities of RF wave propagation make accurate information inaccurate in different locations. We test many tags, with many readers, and discover which tags work best with which readers- AND MOST IMPORTANTLY- which readers have source code that can be incorporated into a savant system. In terms of new generation tags, I have an interesting article written by ODIN labs by information given by Daniel Engels of the AUTOID labs- Daniel is a member of the ODIN team and we have exclusive rights to him. When the article is published, I will ask my CEO if I can post it for all to read. It gives all the information behind Class1 Gen2 tags that one would ever need, even the anti-collision protocols, which have been put into simpler terms with simple diagrams/analogies for all of us who aren't computer scientists out there (I'm definitely not one of them). I hope to inform you soon.
Hagan
ODIN technologies
www.odintechnologies.com |
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kevinchung
Starting Member
5 Posts |
Posted - 02/13/2004 : 14:02:31
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To Tom Napier's question:
Hi Tom:
All of the test results I quoted on 13.56 MHz apply to I-CODE 1 & 2 from Philips Semiconductors. I-CODE 2 is fully ISO 15693 compliant.
All of the white papers I mentioned are posted in our website www.avantetech.com. You can download them easily. I will post the FAA reports once I confirm with them once again. (It does carry "sensitive security information" label on.)
Specifically, go to "RFID Technology" section the white paper titled:
" Low Cost and Reliable RFID Tags for All Frequencies".
Tom,
You can reach me at 609-799-8896x138 besides the email address.
To Hagan's questions and comments:
1. My mentioning of weather is not being fallacious. In page 20 of an IBM position paper "Global Commerce Initiative EPC Roadmap", one of the draw back quoted is "Does Not Work in Moist Environment" for UHF from 300-1200 MHz.
2. You are exactly right in terms of cost of tag when they become too big. In 13.56 MHz, AVANTE has found a way to produce tags at 4-5" square at the same price as smaller tags. We are pricing them today at $0.30 for EPC tags in reasonable volume of 10-100 million.
3. The material (please refer to the white paper refer to earlier) is flexible and stable at high temperature for soldering operation. We call them "COUPLER". They are directly laminated on paper. No hard PLASTIC cover is used. We do not use FR4 board material just to make believe. In deed, the only problem in making RFID tags are exactly that "Low Cost and Reliable.." as the title of our white paper suggests.
4. As for the actual environment, Hagan, you are correct. All application testing must be done in actual usage environment. The test results on the fast speed conveyer were done in Newark Airport underneath the conveyer belt of Continental Airline just to simulate the actual condition. Interference from outside sources as well as same systems located close by is another topic for another day. We have use 30 portals in the same tradeshow arena successfully with innovative approach. Most system engineer will not even dare to try.
5. Hagan, what you found about the lack of reliability of the RFID tags from the top 5 vendors cannot be overemphasized. When I talk to some of them, their only answers were that these tags are only used for a short time. As engineer, this is maddening. Reliability for short time is no reliability at all! In fact, many people found that when they receive tags from supplier, only 70% is good. I cannot agree with you more: "this could be a potentially HUGE problem for RFID's reputation".
6. The tags AVANTE produce are extremely durable once laminated onto paper label or plastic carrier such as wristband, etc. We use them for visitor badges in our tradeshow and event management program (www.leads-trakker.com). We have people used them for exposure to 300C for 20 minutes or longer.
Regards,
Kevin |
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steveheap
Average Member
220 Posts |
Posted - 02/13/2004 : 19:19:02
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Kevin
Thanks for an extremely informative explanation of the issues. I have added your white paper to the "white paper" section of this site. I havent had time to read it in detail, but at first glance it appears to be extremely comprehensive.
At the risk of showing my ignorance, does the EPC standard for tags simply refer to the bits and the structure of the bits on the chip, or does it also define the frequency to be used - ie 13.56 or 915MHz.
Steve |
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Hagan
Starting Member
8 Posts |
Posted - 02/16/2004 : 04:10:37
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Kevin,
Absolutely, 100% fabulous article explaining the material side of RFID technology. As a materials guy myself, I am ecstatic that someone is focusing on the actual chemistry behind tag approach. Afterall, materials are needed before radio waves, circuits, and chips can be produced. Thank you for the research. I will tell you now, ODIN technologies is interested. Of course, we have not tested your tags yet, and cannot be sure, but your approach, information, and Table 3 from your whitepaper is truly something I have not seen yet. I, not necessarily ODIN, believe the airline industry will adopt 2.4 GHz or 13.56 MHz for baggage handling simply to conform with world open air frequency standards. Moisture and metal effect tags more and more at higher frequencies, as you have said, and, if your tags are durable like you say, and can be read at speeds claimed, it will be a truly impressive group of products indeed. I have one question- is nickel-palladium being used for contact pads? That seems a little expensive- might as well go platinum-iridium (jk)- but I do wonder how much less thickness would be needed for a super-precious alloy, and if it would cost effective? Maybe another whitepaper Kevin?
For everyone else not completely familiar with Kevin's emphasis on 13.56 MHz tags- it is a great idea. 13.56 MHz can be used around the globe in the airline industry, and, if the tag truly performs as claimed in that it can be read from any oritentation, in the supply chain. ODIN would have to test before backing up any tag, of course, but leaning toward a tag producing 100% efficiency IS THE ULTIMATE GOAL folks. Nothing else will do.
Hagan
ODIN technologies
www.odintechnologies.com |
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kevinchung
Starting Member
5 Posts |
Posted - 02/16/2004 : 05:56:46
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To Steve:
That would had been the commonsense approach to the EPC concept.
But "historically", that was not the case. The original EPC protocol included the air interface. And it was for 915 MHz only. That is one of the reasons the whole supply-chain world is tilted to 915 MHz based on the promise of "free-air" longer read distance only.
The EPC protocol for 13.56 MHz is now available as a proposed standard. Of course, it may be a moot point now that EPCGlobal is taking over the steering of the standards.
There were three points (they called them "practical issues") that IDC folks pointed in December 2003 to that RFID will bubble and burst: (1) poor tag reliability, (2) many sources of signal interference, and (3) slow standards development.I think the folks in IDC are right on if we do not take corrective actions fast and furious.
To Hagan,
Thanks for the nice compliment. I will call you tomorrow to invite your team to our facility to witness and give your tags to play with for the 13.56 MHz system. We will also provide you some of these special antenna arrays to play with as well.
As for the cost of metallization for oxidation resistance, it is indeed expensive. Not because of the material (nickel-silver is fine), they are only a flash and only needed on the contact areas. Instead, it is the cost of processing when we are counting pennies. We have tried many ingeneious ways to contact-plate the etched or thin film metal traces but encountered too many cost issues. We eventually ended up with the "chip-jumper" or what the industry is now calling "strap" approach to provide both a cross-over path and direct soldering at the contact areas. It is much easier to make a low cost and high temperature stable substrate ("COUPLER") for soldering interconnection than to get back to the old problem of plating precious metal at low cost.
Kevin
kchung@aitechnology.com |
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Carter1945
Starting Member
3 Posts |
Posted - 05/23/2004 : 16:47:03
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I have been reading the thread of the topic and want to say you two guys have the issue well defines, but finding the solution seems to be still elusive. I hope to read more as the posting grows.
Now for my 25 cents.
Having been in RF for a long time, I always know that measurements are a big item, but I have yet to find a reader or RF receiver for RFID such that the support tech or customer can see the signal strength.
==============================================
I have been searching the web for a technical support requirement, which is to be able to read and record the RF.
I am not looking to spend 50,000 USD, but hoping someone might know of a design or kit, which can be used to pick up the RF from the reader and display it on a PC Laptop.
I have been in several situations where the reader and the tag should have been communicating, but there does not seem to be active communications. Thus I need to confirm that there is RF from the reader and a response from the tag in order to eliminate those components.
If anyone has been familiar with the War Driving of Wi-Fi and the various home brew equipment that can be connected to the Laptop, I am looking for the same but for RFID and the various frequencies.
Thought and ideas would be greatly appreciated
> Carter Robinson
US based phone: +1.770.446.5216
Worldwide phone: +1.770.329.4688
US based fax: +1.770.446.1931
E-Mail: engineer@mindspring.com
Home page: http://engineer.home.mindspring.com/
> An innovative and reliable customer focused
> professional determined to solve problems
> with enthusiasm and humor.
=> Carter Robinson
US based phone: +1.770.446.5216
Worldwide phone: +1.770.329.4688
US based fax: +1.770.446.1931
E-Mail: engineer@mindspring.com
Home page: http://engineer.home.mindspring.com/
> An innovative and reliable customer focused
professional determined to solve problems
with enthusiasm and humor.
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Reading distance
