16091 Views 14 Replies Latest reply: Feb 6, 2012 1:10 PM by MircoCadamuro

Tom500

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Aug 29, 2011 1:03 PM

Passive RFID Equipment and Tags

I have a project where passive RFID tag technology seems to be a potential solution. My application includes a need to send out a 30 meter signal, determine if multiple tags are within the range and report what tags are present and with ones are missing. The tags may be in the open, behind wood or possible even metal.

Can anyone direct me on what equipment I could aquire to begin my testing? Or direct me on good place to start?

Thank you.

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Tags: passive_rfid

heatherjo
1 posts since
Jul 26, 2011

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Aug 29, 2011 2:27 PM (in response to Tom500)
Passive RFID Equipment and Tags

Tom500 - let me research this for you by asking someone in my RFID product group. I'll be right back to you.

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- Tom500
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  Aug 29, 2011 2:32 PM (in response to heatherjo)
  Passive RFID Equipment and Tags
  
  Awesome. Thank you.
  
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LevyOlson
13 posts since
Aug 15, 2011

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Aug 29, 2011 2:57 PM (in response to Tom500)
Passive RFID Equipment and Tags

Hey Tom,

In my experience, a Passive RFID system will be pushing it boundaries at 10-20feet. I have heard of people using a UHF system, with multiple antenna's getting 60feet open air, but that is about the limit. In order to achieve your goals you are going to have to switch to an active system. My recommendation would be to look at the EZ430-RF2500 Development kit.

The EZ430-RF2500 Dev kit from Ti is a 2.4GHZ kit that contains a two target boards and a USB debug interface. The reason I though this would work for your application is that TI has provided a very nice GUI demo of a wireless senor nodes. On the demo program you host will sit and wait until target boards connect. Once they connect to the target board they show up on the GUI as a node.

The best thing about this solution is the EZ430-RF2500 is $50.00 and you can buy extra target boards for just over $20. I have included links to the dev kit and target boards below.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-23031-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-23125-ND

Let me know if you have any other questions.

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- Tom500
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  Aug 29, 2011 3:19 PM (in response to LevyOlson)
  Passive RFID Equipment and Tags
  
  Levy,
  
  My problem is I can not have a power source at the end item and the tags must be fairly small. I assume an active system requires a power source on both ends correct?
  
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  - LevyOlson
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    Aug 29, 2011 3:41 PM (in response to Tom500)
    Passive RFID Equipment and Tags
    
    Tom,
    
    Yes, an active system would require power at both ends. When making my suggestion i did think about the size of the tag in the field. That is where we would get in trouble as well. In RFID usually the bigger the tag the longer the read range. This has to do with the fact that bigger tags have larger internal antennas
    
    The target board of the EZ430-RF2500 is actually fairly small, being about the size of two AAA batteries (which happen to be the power source of the target boards). So in actuality these target boards could be actually smaller that the RFID tag you would need. TI does have a reputation of having lower power products, so you could play around with the "awake" time on the target boards and extend battery life significantly.
    
    Is size your main concern about an active system?
    
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    - Tom500
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      Aug 29, 2011 3:49 PM (in response to LevyOlson)
      Passive RFID Equipment and Tags
      
      Levy,
      
      Both tag size and ability to access batteries. What if I could live with a 10 to 15 foot range. Do you think RFID could handle this with small size tags? Maybe 1 inch square.
      
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      - LevyOlson
        13 posts since
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        Aug 29, 2011 4:28 PM (in response to Tom500)
        Passive RFID Equipment and Tags
        
        Tom,
        
        Actually I just found a really great FAQ on TI’s site that covers some of the different factors that affect read range.
        http://www.ti.com/rfid/shtml/cust-support-faqs.shtml#Tthree
        
        I don't think you could expect to see 10 to 15feet of range on that size of tag. Especially if it is on something metal, like you eluded to earlier.
        
        To get a 10 to 15 foot range you are going to have to use a large tag with one or perhaps even multiple large antennas.
        
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        Tom500
        7 posts since
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        Aug 29, 2011 5:30 PM (in response to LevyOlson)
        Passive RFID Equipment and Tags
        
        Thanks Levy, The TI link had lots of good information. BTW, great fish in your profile picture.Where did you catch it?
        
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        LevyOlson
        13 posts since
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        Aug 30, 2011 8:46 AM (in response to Tom500)
        Re: Passive RFID Equipment and Tags
        
        Thanks! I caught it in Canada on Caviar lake. We stayed at www.jimscaviarcamp.com. It was an unbelievabley good time and good fishing.
        
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Alec
62 posts since
Mar 22, 2011

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Aug 29, 2011 3:00 PM (in response to Tom500)
Passive RFID Equipment and Tags

Tom500,

I'm not an expert on RFID by any means, but I'm not sure if a 30 meter range is possible with passive RFID. Most of the passive implementations I've seen have been a couple feet at most (usually card readers).

This page is claiming 50 feet has been accomplished, but I'm not sure if it's a true passive solution or not...

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- Tom500
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  Aug 29, 2011 3:16 PM (in response to Alec)
  Passive RFID Equipment and Tags
  
  Alec,
  Thanks for the link and information. Very helpful.
  
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  - AndyLee
    1 posts since
    Sep 7, 2011
    
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    Sep 7, 2011 7:03 PM (in response to Tom500)
    Re: Passive RFID Equipment and Tags
    
    Hi Tom500, if you are working on tagging metal products, I would highly recommend you to check out these products :
    http://www.xerafy.com/product/microx-ii
    http://www.xerafy.com/product/micro
    Xerafy has excellent products either ON metal or even IN metal, check these products and you will be impressed. They have the best and smallest footprint per reading distance.
    These are passive tags and the reading distance can go up to 12m on metal for the MircoX II, and up to 6m in metal with the Micro-iN.
    Wish you all the best.
    
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    - Tom500
      7 posts since
      Aug 29, 2011
      
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      Sep 7, 2011 10:17 PM (in response to AndyLee)
      Re: Passive RFID Equipment and Tags
      
      Excellent information. Thank you.
      
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MircoCadamuro
1 posts since
Feb 6, 2012

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Feb 6, 2012 1:10 PM (in response to Tom500)
Re: Passive RFID Equipment and Tags

Hi All,
the problem here is not the read range, but the need to read tags behind other objects.
In the market, there are very few passive RFID tags (only UHF passive) you can read at 30 m distance, but you must have no obstacles between tags and reader, in particular no metallic obstacles (i.e. metal plates). Furthermore, those suitable tags are much bigger than 1 inch square.
I think you can use active tags only.
If interested in more information about RFID tags, please visit VeryFields, the largest information source about RFID tags, and read this guide for an overview on differences between passive, active, semi-passive and BAP tags.
I hope it could be useful.
Regards,
Mirco

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