RFID Reader Range

Hi @inq,

  I have just done another quick Google run around, based on the 3M unit name you showed. The following is completely out of my experience, so treat as items of further research ... certainly not facts!

  I got the impression the 3M unit you showed might be looking for something known as Tattle-Tape ... which is an electro-magnetic 'strip' - NOT RFID. You can buy it boxes of 1000 or 5000 strips ...

Each strip has two states ... active and de-activated .. and is changed from one state to the other by applying magnetic fields. Hence, when a book is 'checked out' at the desk it is deactivated. Taking a strip near the detector, which is still active, sets off the alarm. However, the detector has no way of knowing which article  has been detected.

This implies each 'fully protected' book has both an RFID tag and a Tattle-Tape strip.

I suspect the library desk has a different detector that is reading the RFID tag, to record a book is being checked out (or back in again). The RFID tag, including its coil shaped antenna is what your book photo showed. Of course the desk unit may have integrated the two systems into a single unit to make the checking in and out process as easy as possible.

References I found include:

• https://www.bibliotheca.com/library-supplies/
• https://en.wikipedia.org/wiki/Electronic_article_surveillance
• https://multimedia.3m.com/mws/media/385543O/3mtm-detections-system-3800-product-sheet.pdf?fn=3M%20Detection%20System%203800.pdf
• Also 3m-2301-user-manual.pdf at manualsbrain.com (use Google to find the url)

------

Note that 'by chance', the name mentioned in your photo ... bibliotheca ... is also the one I found looking for Tattle-Tape ... and the page at

https://www.bibliotheca.com/library-supplies/

All Bibliotheca RFID tags are compliant with ISO 18000-3 mode 1 and ISO15693 air interface protocols. The SLi-1 and SLi-2 chips are capable of storing data in the industry standard ISO 28560 format. In addition, all Bibliotheca RFID tags include a 50-year or 100,000 read-write data retention guarantee.

A quick Wikipedia check on the Iso air interface protocols mentioned:

https://en.wikipedia.org/wiki/ISO/IEC_18000-3

https://en.wikipedia.org/wiki/ISO/IEC_15693

suggests that the tags are 13.56 MHz

----------

So maybe your original 125kHz Amazon item was totally unsuitable anyway!

---------

As I said above, this is all speculation on my part .... I offer it merely as hints for you to do some more digging to discover the truth.

Good luck! Dave

@davee - Thank you for giving me a head start.  Even here at 5AM, took me all of ten minutes and several re-loads to read your post.  Looks like I'll need to head into the library to actually do some research with your links. 

I've been able to do a little research here... Read over your first link and saw the Tattle tape images.  Followed your "ISO 18000-3" logic and saw that the library's tags use the 13.56 MHz range.  😣 Bummer!  The readers I have coming in (hopefully) today, won't read them.  Well, pulled that trigger too quick!

I have a hard-cover book and a book-on-CD checked out.  They both have the RFID tag, but I don't see the Tattle tape, but maybe I won't because...

Last night... although I did not get a chance to talk to the IT guy doing the book reader or the head librarian, I usually deal with as part of my Library Board duties, I did talk to an assistant librarian yesterday.  He believed that the 3M unit was not working.  They couldn't afford the, in his words, "exorbitant service contract fees".  I'll need to talk to the head-librarian about that issue.  

Doing a little Amazon searching, I didn't find any readers claiming more than 2 inches (that were < $100)  I know the wand at the library works and doesn't require any special licenses, so its range of ~12 inches is still not violating FCC type rules.

With an experimenters mind-set, I'd like to ask anyone with the requisite electronic hardware skills or RF type knowledge, their best guess ideas.  I'm not looking for any guaranteed type answers... just something better than 50-50%.  Or my winning record of 0/1! 🙄 

I'm just thinking out-loud here... what might I do to increase the range of something like  "https://www.amazon.com/Sensor-Reader-Module-13-56MHz-Arduino/dp/B077T38Q8H/"?

My rudimentary thoughts are:

1. that I can disable the antenna on the board, by cutting it after the attach point and simply solder an external one.  I think the external antenna needs to be some fraction/multiple length of the frequency??? or something like that.  
2. Could I put some amplifier in-line between the attach points and the external antenna?  

... both are beyond my pay-scale.  Any ideas???

VBR,

Inq

@inq While my RF days are very small in the rear view mirror I can comment on two points. YES any antenna needs to be sized to the frequency. There is a lot of engineering in that but will be well documented and I am sure someone else here has current first hand knowledge.

I also do recall building an antenna pre-amp decades ago but for frequencies in the tens of meters. IIRC, while it will boost the signal, it will also boost any noise as well. IIRC, I think I had a tuning circuit involved that fine tuned the signal depending on what frequency I wanted to boost. With your situation because it is a single frequency, a static RC will do the job. 

Hi @inq,

   Do you have days in which you try to find answers ...  but actually end up with about half an answer and 10 times as many new questions? 🤨 

---------------

Of course, I can't be sure the 3M unit you showed a photo of is a 'Tattle-Tape' machine ... it is just where Google seemed to link up to. It is possible that it 3M are also into making RFID machines. So please treat all my comments like 'potential suspects' on a 'Who dunnit board?' ... you have to dig further and decide which ones are guilty and which ones are innocent bystanders with dodgy alibis.

I 'suspect' the Tattle-Tape detection is more difficult to fool than RFID ... in which case it might make sense to combine the two mechanisms if 'simple' theft through a gateway is a significant concern. Thus the RFID provides the possibility of tracking individual objects when treated in a 'legal' manner.

-------

Looking a little more into 13.56 MHz RFID game ... there seem to be several 'protocols' ... and the possibility of encryption, suggesting the need to understand what you are dealing with more fully. Plus, the possibility that the tags you are trying to follow are in some way proprietary or otherwise tricky to deal with.

So personally, I am inclined to suggest you change tack a little. Start by establishing a system that can read and mak sense the tags at short range, then look at the problems of stretching the range.

I suspect stretching the range is 'do-able', though maybe with considerable difficulty ... but until you have tracked down the exact protocol, etc., you will wandering around in a complete pea-soup fog without even being sure you can scan the book at zero range.

-------------------

The card you found is based RC522 .. which appears to corresponds to the keyring tag example sensor included with many of the Arduino multi-sensor 'educational' kits.

As such kits come with near-zero info, I suggest looking to the chip manufacturers. As an initial suspect, I suggest https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf

Please note I am only matching up numbers, and assuming they correspond for a reason.

.....

To widen the search, try looking at Adafruit .. https://learn.adafruit.com/adafruit-pn532-rfid-nfc

And note that they admit to only having a few suggestions as where to start, when usually they provide a 'tested and documented' mini-project.  i.e. you are not alone in the fog .. and they are choosing the tags to read ... you are being provided with 'mystery' tags!

This board is based on PN532 ... which I linked to https://www.nxp.com/docs/en/nxp/data-sheets/PN532_C1.pdf

Note that NXP recommend some more recent replacement chips for newer projects. They also have application notes, etc. ... probably by the bucketful ... I haven't followed that far.

The Adafruit board itself is a little painful on the credit card, so you might want to see what our friends in the Far East can offer.

-------

Good luck my friend ... your quest is only just beginning!

Best wishes, Dave

Hi @inq,

 Sorry, I meant to comment on your questions abiut replacing the antenna on the board you showed.

 I think this will be a case of RTFM (Read the F manual) ... or in this case data sheets and application notes. I haven't checked but I suspect the antenna that 'circles' around the board is meant to be part of an coil/capacitor resonant circuit. It may well be possible to 'disconnect' the existing loop and replace with an alternate, but unfortunatley a simple dipole or quater-wave is almost certainly not going to be effective.

And even if it was, a quarter-wave (single (often vertical) rod, equivalent to the 6cm 'sticks' sometimes used for WiFi and mobile phones) at 13.56 MHz is around 5.5 metres long, and a dipole 11 metres ... might be a bit inconvenient to use in the library?

As I mentioned, I spotted application notes with titles suggesting antenna design adajacent to the chip data sheets, so if you get far, I think the information you need is 'out there'.

----

But I would start by seeing if you get a prototype system that works, using the 'built-in' antenna provision at near zero range, first. New antennas can be part two ....

Best wishes, Dave

Posted by: @davee

Do you have days in which you try to find answers ...  but actually end up with about half an answer and 10 times as many new questions?  

You mean... days come in other ways?  😋 

I'm not too concerned about the 3M unit and tattle-tape anymore.  I was falsely assuming (0:2 now) the 3M door unit used the same RFID tags and was holding it up as... "here it scans several feet and all I need is 6-12".  But the "theoretical" project is to just scan books for inventory procedures on the shelf... not a replacement system for scanning, checking out and security.

I think your advice is solid to worry about distance later (Part 2)... when (or if) I can successfully read them.  (Part 1)

I doubt they're encrypted and they are supposed to report the same thing that is on the bar codes.  So I'll know it pretty quickly if any thing comes puking out.  I've read something that says the cell phone NFC system is the same frequency range.  I'll have to experiment with that tonight and see if a phone can read the book tags.

I do want to ask a Part 2 question since you used the key words I was kind of expecting an RF guy to know... This is my understanding of antennas.  Is this correct?

This comes from my knowledge back in the CB radio days.  I know that antenna is suppose to be extremely long. They fixed that by just winding it up on the cylinder part and only sticking out some nominal portion.  Using that concept... If the magic number for 13.56MHz is 5.5 meters, can't I simply wrap a 5.5 meter wire around a template say 6" diameter and connect to two ends to those solder points???

My ignorant assumption is that the length of that antenna around the PCB perimeter is some even fraction of the desired... aka 5.5 m... and since its not the full 5.5, its handicapped to the fractional inch read range.  

VBR,

Inq

Posted by: @davee

Hi @inq,

 Sorry, I meant to comment on your questions abiut replacing the antenna on the board you showed.

 I think this will be a case of RTFM (Read the F manual) ... or in this case data sheets and application notes. I haven't checked but I suspect the antenna that 'circles' around the board is meant to be part of an coil/capacitor resonant circuit. It may well be possible to 'disconnect' the existing loop and replace with an alternate, but unfortunatley a simple dipole or quater-wave is almost certainly not going to be effective.

And even if it was, a quarter-wave (single (often vertical) rod, equivalent to the 6cm 'sticks' sometimes used for WiFi and mobile phones) at 13.56 MHz is around 5.5 metres long, and a dipole 11 metres ... might be a bit inconvenient to use in the library?

As I mentioned, I spotted application notes with titles suggesting antenna design adajacent to the chip data sheets, so if you get far, I think the information you need is 'out there'.

----

But I would start by seeing if you get a prototype system that works, using the 'built-in' antenna provision at near zero range, first. New antennas can be part two ....

Best wishes, Dave

Posted by: @inq

This comes from my knowledge back in the CB radio days.  I know that antenna is suppose to be extremely long. They fixed that by just winding it up on the cylinder part and only sticking out some nominal portion.  Using that concept... If the magic number for 13.56MHz is 5.5 meters, can't I simply wrap a 5.5 meter wire around a template say 6" diameter and connect to two ends to those solder points???

My ignorant assumption is that the length of that antenna around the PCB perimeter is some even fraction of the desired... aka 5.5 m... and since its not the full 5.5, its handicapped to the fractional inch read range.  

@ing.. The answer is , there's a lot more to designing an antenna system than just simply wrapping wires around a template.. impedance matching, and SWR needs to be considered, and what type of antenna you are using, ie, omnidirectional, directional, etc.. So the question is, what is the RFID transmitters output impedance, and how do you match it with an antenna that will work efficiently with both the Tx and RX signals..I'm almost sure that the RFID board has  antenna matching circuitry for it's existing antenna, so probably not a good idea to cut it loose..just my opinion of course.  

regards,

LouisR

@inst-tech 

Toto - I guess we're not in Kansas making radios out of razor blades and pencil leads anymore.

@inq That will be state of the art after the next big solar flare wipes out all the satellites.

Posted by: @inq

Toto - I guess we're not in Kansas making radios out of razor blades and pencil leads anymore.

 

 Indeed, If for the benefit of science you must experiment, then I say, go for it!  lol

Besides learning that the subject of antenna theory is both complex and well above  and beyond "the state of the art  of razor blades and pencil leads" As Ron puts it, it will probably make a very nice project for your makers group to zoom in on.

I look forward to seeing what you come up with, as technology today will change in the future, just as it always has, thanks to the intrepid tinkerer who refuses to except "can't be done" as a final answer.

kind regards,

LouisR

Hi @inq,

   Ok, so hopefully we are getting somewhere .. though probably, still a fairly long way from where you need to be to have a solution.

There are others on this forum who are more experienced to give a full answer regarding your CB experience, but my simplistic understanding is that the aerial you had was 'short' compared to the 'ideal' length, but you traded some loss of performance for convenience of not needing it to be around 2.8 metres in length. The coil helped to transfer as much power as possible from the output stage into the antenna.

However, the design notes for the PN532 chip look much more involved ... read on ..!

-------

One of the issues you need to sort is identifying the protocol ... as a start point I note the PN532 data sheet claims it supports 6 different protocols

8.6 Contactless Interface Unit (CIU)
The PN532 CIU is a modem for contactless communication at 13.56 MHz. It supports 6
different operating modes
• ISO/IEC 14443A/MIFARE Reader/Writer.
• FeliCa Reader/Writer.
• ISO/IEC 14443B Reader/Writer
• ISO/IEC 14443A/MIFARE Card 1K or MIFARE 4K card emulation mode
• FeliCa Card emulation
• ISO/IEC 18092, ECMA 340 NFCIP-1 Peer-to-Peer

The same section also says:

• Typical operating distance of 50 mm in ISO/IEC 14443A/MIFARE or FeliCa in
Reader/Writer mode depending on the antenna size, tuning and power supply
• Typical operating distance of 50 mm in NFCIP-1 mode depending on the antenna
size, tuning and power supply
• Typical operating distance in ISO/IEC 14443A/MIFARE card or FeliCa card operation
mode of about 100 mm depending on the antenna size, tuning and the external field
strength

So it looks like you are going to need to increase performance from the base level to achieve the distances you want. In addition, I have a suspicision that the 'ideal' position for your sensor will be occupied by the adjacent books ... moving out from the shelf to be 'behind' the spine will probably reduce the visible signal.

----------

Alongside the data sheet for the PN532 are several application notes, which include notes on how to design the antenna.

https://www.nxp.com/docs/en/application-note/AN1445_An1444.zip

There is also one in which a simple two transistor amplifier is added

https://www.nxp.com/docs/en/application-note/AN1425_AN166510.zip

----------------

Note that PN532 is an old design .. the chip has probably been cloned to produce the boards on Amazon and the China based sites like AliExpress and Banggood.

NXP has produced several new designs, such as the PN7160 which claims to have an enhanced range mode, though I didn't spot any data as to its effectiveness .. see https://www.nxp.com/docs/en/application-note/AN13219.pdf

How readily available board level products are I don't know. Note that these more recent designs have updated, but superficially similar antenna design notes, so experience with the older chips is probably transferable.

----------------

Also Adafruit have tried to improve the range:

https://cdn-shop.adafruit.com/datasheets/PN532_AntennaDesign_v1.0.pdf

-----------

A lot more reading .. but simple solutions that provide the kind of range you are looking for is still elusive.

Best wishes, Dave