RFID Reader Range

Posted by: @inst-tech

@inq There is a typo error in my last post..XC=1/2πfC) and in an inductive circuit, as frequency goes up, reactance ( impedance) goes down Xl = 2πfL). the combination of the two reactance's equal total impedance, and this will affect the power output.

 

Xl = 2πfL, as frequency goes up , impedance goes up, as you can see by the formula. Sorry about that, I'll have to preview my post better before I post them..fat fingers gets me every time..lol

Regards,

LouisR

I'm hoping I don't have to get down into these weeds.  The tags are already defined and if @davee is correct, my reader options will get very limited.  Finding a cheap model with the desired range (6-12 inches) may be problematic.  

However, souping-up a car or an electronic device is well within many of the members of this forum.  And these equations will point the direction of modifications.  I have faith... we will prevail.

VBR,

Inq

Posted by: @inq

Posted by: @inst-tech

@inq There is a typo error in my last post..XC=1/2πfC) and in an inductive circuit, as frequency goes up, reactance ( impedance) goes down Xl = 2πfL). the combination of the two reactance's equal total impedance, and this will affect the power output.

 

Xl = 2πfL, as frequency goes up , impedance goes up, as you can see by the formula. Sorry about that, I'll have to preview my post better before I post them..fat fingers gets me every time..lol

Regards,

LouisR

I'm hoping I don't have to get down into these weeds.  The tags are already defined and if @davee is correct, my reader options will get very limited.  Finding a cheap model with the desired range (6-12 inches) may be problematic.  

However, souping-up a car or an electronic device is well within many of the members of this forum.  And these equations will point the direction of modifications.  I have faith... we will prevail.

VBR,

Inq

Indeed @inq, I too have faith that someone, more knowledgeable than myself, can figure out how to get to the desired range of 6-12 inches... 

Regards,

LouisR

Hi Ron @zander,

  This may be veering of the original thread question, and I may be confused, but my understanding is:

• Bluetooth is 2.4GHz, bidirectional radio comms .. a completely different protocol, but hardware wise at the radio frequency end, a close cousin of 2.4G WiFi. (e.g. Some options of ESP32 and ESP8266 can support both.) Bluetooth tags are powered computers, albeit the protocol includes options for very short, infrequent transmissions, so sometimes the power source may be very small - e.g. a coin shaped battery. In principle, power harvesting techniques might be used to 'collect' power in suitable applications, although I don't recall any examples of this.
  • I have never used any of the tags/tiles in the marketplace for attaching to keys, etc. .. I noticed this review of Apple versus 'Tile' ..  https://www.independent.co.uk/extras/indybest/gadgets-tech/apple-airtag-vs-tile-pro-compared-b1849518.html
  • It seems both use Bluetooth, with Apple adding UBW function .. and both are in the £20-£25 each  price range. I have seen others, and I seem to recall they are not much cheaper. I can see they could be made cheaper than this, but are intrinsically much more complex than existing tags, so I suspect will always be higher priced, in spite of economies of scale and low labour cost countries.
•  
• NFC - Near Field Communications - refers to using the electric and magnetic fields very close to the transmitter - in many cases, such as door entry and payment systems, the inherent short range provides the security and privacy needed, so that the card or smart phone doesn't need to make physical, electrical contact, but must be very close. In these applications, the field from the 'reader' can be sufficient to power a passive tag, whilst if it is (say) a smartphone which is 'emulating' a payment card, then obviously both the reader and the tag are actively powered.
•  
• RFID Radio Frequency Identification refers to a tag that is activated by a radio transmission, and the tag then responds, by transmitting a response. Some tags are powered by a battery, but the majority 'collect' energy from the activating radio transmission, and use it to become a transmitter. RFID can be either NFC or 'conventional' radio propagation, the latter enabling longer range detection.
•  
• The detection range of RFID tags seems to increase with frequency ... 125kHz is happiest up to about 50mm (2"), although it can be pushed further - possibly by using receiver unit coils which   ... 800-900MHz several meters, with 13.56MHz somewhere in between.

Hope this is informative and maybe 'accidentally' triggers somebody to have a great new idea!!

Best wishes, Dave

@inq Why would it have to pull it out, a laser type targeting system might work.

Posted by: @davee

Hi Ron @zander,

  This may be veering of the original thread question, and I may be confused, but my understanding is:

• Bluetooth is 2.4GHz, bidirectional radio comms .. a completely different protocol, but hardware wise at the radio frequency end, a close cousin of 2.4G WiFi. (e.g. Some options of ESP32 and ESP8266 can support both.) Bluetooth tags are powered computers, albeit the protocol includes options for very short, infrequent transmissions, so sometimes the power source may be very small - e.g. a coin shaped battery. In principle, power harvesting techniques might be used to 'collect' power in suitable applications, although I don't recall any examples of this.
  • I have never used any of the tags/tiles in the marketplace for attaching to keys, etc. .. I noticed this review of Apple versus 'Tile' ..  https://www.independent.co.uk/extras/indybest/gadgets-tech/apple-airtag-vs-tile-pro-compared-b1849518.html
  • It seems both use Bluetooth, with Apple adding UBW function .. and both are in the £20-£25 each  price range. I have seen others, and I seem to recall they are not much cheaper. I can see they could be made cheaper than this, but are intrinsically much more complex than existing tags, so I suspect will always be higher priced, in spite of economies of scale and low labour cost countries.
•  
• NFC - Near Field Communications - refers to using the electric and magnetic fields very close to the transmitter - in many cases, such as door entry and payment systems, the inherent short range provides the security and privacy needed, so that the card or smart phone doesn't need to make physical, electrical contact, but must be very close. In these applications, the field from the 'reader' can be sufficient to power a passive tag, whilst if it is (say) a smartphone which is 'emulating' a payment card, then obviously both the reader and the tag are actively powered.
•  
• RFID Radio Frequency Identification refers to a tag that is activated by a radio transmission, and the tag then responds, by transmitting a response. Some tags are powered by a battery, but the majority 'collect' energy from the activating radio transmission, and use it to become a transmitter. RFID can be either NFC or 'conventional' radio propagation, the latter enabling longer range detection.
•  
• The detection range of RFID tags seems to increase with frequency ... 125kHz is happiest up to about 50mm (2"), although it can be pushed further - possibly by using receiver unit coils which   ... 800-900MHz several meters, with 13.56MHz somewhere in between.

Hope this is informative and maybe 'accidentally' triggers somebody to have a great new idea!!

Best wishes, Dave

 

Indeed @davee..I ran across this site: https://www.wireless-technology-advisor.com/rfid-frequencies.html

in doing a little research on the RFID's.. It appears to me that there are many other factors that limit the frequency that can be used, such as,

• Which countries you can operate in (legal restrictions)
• The distance over which you can read RFID tags
• How fast you can read RFID tags
• Tag size (may limit the size of the object you can tag)
• What surroundings you can and shouldn’t operate in
• Buy price

RFID is most often used in one of these four frequency bands...

• Low Frequency (LF) 125 to 134 KHz band
• High Frequency (HF) 13.56 MHz
• Ultra High Frequency (UHF) 433 MHZ and 860 to 956 MHz band
• Microwave Frequency 2.45 to 5.8 GHz band

It’s important to understand the strengths and limitations of each band when you plan your application.

Radio regulations limit transmit power

For example, at present, the regulations in the USA limit the transmit power to 4Watts EIRP in the UHF band.

The EIRP (Effective Isotropic Radiated Power) limit helps prevent interference that might occur if you transmitted a very intense beam of radio energy from a highly directional high-gain antenna.

Conclusion: it also appears that due to restriction on power emitted by the Antenna system, that too, will limit all the other facts afore mentioned. 

The article is quit specific on benefits and limitations of using higher frequencies..This is something that should be considered when selecting an RFID system.. alot more to it than meets the eye...lol

Anyway, I thought I just pass this along to those that might find it interesting as I did.

Regards,

LouisR

Hi @inq, @inst-tech, @zander,

Maybe increasing the size of the coil with a low powered device like the Melexis chip is feasible, but I suspect you will need some test equipment far beyond a multimeter to figure out what is happening. Whether the boards on Amazon etc could be similarly treated is a wider version of the same question. I guess this is the nearest to your preferred course of action, but at the very least, expect to see at least a chip or two expire on your quest. (Please bear in mind the coils are part of an LC resonant circuit, which in the Melexis chip case not only acts as the receive and transmit antenna, but also determines the operating frequency. Simple L impedance is not the only consideration!

As both Louis and I have noted, there are lots of regulations, etc. How much of a real issue they are is 100% down to you. Usage in public space is much more visible than someone alone in their garage ... and increasing the power in any way, increases the risk of someone being affected.

My very quick perusal of data sheets suggested 125kHz maybe 'yesterday's technology' ... 13.56MHz seemed 'much more today's technology', and this frequency appears to have more range. This maybe a mistake on my part, but at some point, I have a feeling your library may need to do an 'upgrade' , as supporting 125kHz equipment is no longer viable. Whether, that point is now/soon, 20 years time or never, is luckily not my judgement or responsibility. However, if I was doing a 'feasibility' study, then that would certainly be an issue I would investigate and consider.

-----

I note a side suggestion of using barcodes/QR codes .. I assume when you say on the 'back of the book', you mean on the back cover, not the spine, hence the need to pull the book to scan it?

Maybe, consider printing barcodes and sticking to the spine? Lots of obvious downsides, but again the long term view may be different from the short term pain view.

Good luck, Dave

@davee I thought @Inq said there were barcodes already on the spine. Not sure if we know why they are not being used.

Hi Ron @zander,

He said (and I quote):

The books have a bar-code on the back of the book that has the exact same data as the RFID tag.

As I queried above, I presume he means the back cover of the book, not the spine.

But of course, only he can verify that.

Best wishes, Dave

@davee OMG, another senior moment for me?

Hi Ron @zander,

Re:

OMG, another senior moment for me?

   No. You are just like every other person. (And maybe a few AI systems that are trying to mimic 'real' brain operations!)

We are equipped with brains which continually try to 'simplify' the vast amount of incoming information through our senses, by fitting it to a manageable internal model of the world .. hence, if a person makes a mistake, say a typo ... then it is really difficult for that person to spot it, as every time they re-read it, they automatically perceive what that meant to type, not the actual symbols in front of them.

You probably read @inq's words, visualised in your mind a code on the spine  (where you expected it to be), and after that it is practically impossible to read his words and visualise anything different.

Just relax and enjoy the ride!

Best wishes, Dave

@davee, @zander...indeed, if it weren't for making a mistake now and again, I doubt I would have learned very much over that past 75 years...lol

Most of us learn by doing, and making a mistake now and a gain is part of that process as DaveE so eloquently stated in his previous post. The problem of re-engineering something that some other person has designed is that we often forget, (or didn't know) the specific purpose for which it was originally designed.. I ran into that quite a bit as a process controls tech.. Sometimes the design engineers just use a kind of template, and modify it to suit their purpose. Without knowing what the specific process parameters really are, this can be a real headache for those of us left to discover why that process isn't preforming like expected...I learned a long time ago, "if it was easy, every one would be doing it"..lol

Sometimes we just have to resolve ourselves to doing the required research and development to assure success of the project.

regards,

LouisR

Posted by: @davee

This may be veering of the original thread question, ...

Oh!  We never do that around here!  🤣 🤣 🤣 🤣 

Posted by: @davee

The detection range of RFID tags seems to increase with frequency ... 125kHz is happiest up to about 50mm (2"), although it can be pushed further - possibly by using receiver unit coils which   ... 800-900MHz several meters, with 13.56MHz somewhere in between.

Bummer!  Since they have door portals at the library, that would indicate the reader I have coming won't even see my books I have out.

VBR,

Inq

Posted by: @zander

@inq Why would it have to pull it out, a laser type targeting system might work.

It's not on the binding edge... it's on the back cover in the upper-right corner.  As you pointed out there is not enough room on the binding, so for consistency sake, they put it on the back... hidden unless pulled out.

I had to come into the library (Zero Internet at home)!   

As this is a side project for my Maker's Group, I'm sure the Library isn't interested in a the hair-brained idea of a robot trudging along up and down isles.  I'd have to spring it on them after its done and rock-solid... and tell them to just fire it up when they close the place at night.  Point being... they're not about to change anything on the books. 

My semi-technical (user) of the system isn't here now.  I can't get the inventory scanner at the moment and I can't get the specs for the stuff.

Here is the scanner at the entrance ways.  It is a 3M product, but no identifying labels on it besides these.

And here is one of the tags as seen on some paperback.  They're just paper-white and looks like paper until shining light through it.  The bar-code is on the book... not the tag.

@inq Appears to be an Italian company, into all sorts of things to do with books.