Questions tagged [rfid]

Radio Frequency IDentification

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1answer
170 views

Improve 134.2kHz PIT tag RFID reader range

I need to scan 134.2kHz PIT FDX tags from a range of 5cm to 10cm. So far, I have built custom reading circuit. It has the standard R+L+C in series driven by 134.2 kHz square wave and the output is ...
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1answer
207 views

Is it possible to change gain on Adafruit PN532

Is it possible to change the gain on an Adafruit PN532 board? I need to LIMIT the range in order for it to NOT interfere with another PN532 installed close by. The board is to be used with an ...
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2answers
599 views

RFID behavior with aluminum

When I put a piece of aluminum foil underneath an RFID card, the RFID reader is unable to read the card when it's placed in front of it like this (or around it): The reader IS able to read the card ...
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1answer
187 views

Stacked RFID tags

If I have a stack of papers each with an RFID tag in the corner, is there a way for an RFID reader to only read the RFID tag on the top piece of paper, without the RFID tags below interfering?
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0answers
27 views

Base requirements for RFID experiment

I'm quite new to the topic but I would like to conduct an experiment on how RFID wristbands in a hospital setting affects patient satisfaction compared to a control group that will not have RFID wrist ...
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1answer
54 views

Wireless Short Distance Measurement [closed]

Is is possible, and if so, is it viable, to use UHF RFID RSSI to measure distance in the 1-25 millimeter range from the RFID Reader antenna with a resolution down to below half a millimeter? If it is,...
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3answers
7k views

Can strong magnets cause permanent damage to RFID tags?

I have an RFID-enabled ID card for work that is used for building access. While I can use a lanyard, cord-reel, etc. to carry the card and still have convenient access to it, I'd like to simply put it ...
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1answer
39 views

Merging/downsizing RFID cards somehow

I have 3-4 RFID cards in my wallet, and they all work just fine when I press my wallet against the card readers - despite being 4-5 cards deep in my wallet. I want the benefit of having these cards ...
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1answer
418 views

UHF RFID: Why are read range (forward) and backscatter range curves different?

I have made two measurements with a UHF RFID tag (pic below) My test setup consists of a reading device with a sensitivity of -70dBm and an antenna gain of 6dBi. I made a frequency sweep across 700 - ...
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1answer
350 views

Reading NFC tag from a slightly longer distance

Presently, my problem is that I have this NFC/RFID Tag, and due to the small antenna on the tag, it needs to make direct contact with the reader (presently tested using both a smartphone w/ NFC ...
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1answer
72 views

Looking for a short range detection and identification

I am currently building a smart cat door. One of its functionalities is that it keeps the door locked until our cat comes close to it, then it unlocks the door. I tried using RFID, the RC522 because ...
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0answers
265 views

UHF RFID Microstrip antenna

I want to design microstrip antenna for UHF RFID. The chip I'm using is SL3S1013FTB0. I found some demo kits and found some antenna examples. One of them has small antenna that I'm especially ...
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2answers
277 views

How to make the receiver send signal back to the transmitter with wireless RF 433MHz module

I want to buy a RF transmitter & receiver 433MHz on the internet for our research project which deals with radio frequency. I badly need the concept of having the receiver notify the transmitter ...
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1answer
103 views

How can I make my RFID reader restrict itself to the tag in the closest proximity and read only this tag?

I'm looking for a way to detect the user closest to a certain object that has the RFID reader attached to it. Therefore I need my RFID reader to restrict itself to the user closest to it and not read ...
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2answers
6k views

How to design 125Khz Antenna for 1 meter RFID reader

Firstly, I'm not from electronics background so my knowledge is limited in this area. Target System - I am looking to build/ extend the range of 125khz RFID reader upto 1 meter (~ 3ft) to be ...
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1answer
407 views

Equivalent Series Resistance of 13.56 MHz RFID Antenna

I am designing a system that uses the MFRC522 by NXP Semiconductors and I am having a bit of difficulty designing the antenna. NXP provide an antenna design guide under the application note AN1445 ...
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1answer
659 views

What are line-of-sight limitations of UHF RFID readers?

I am looking at some UHF RFID readers for a project and I have a few questions about the overall concept of detecting passive RFID tags. The system is concerned with keeping track of people passing ...
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0answers
57 views

RFID - Detecting items in box regardless of tag orientation

I'm thinking about something, and am wondering if RFID can accomplish this. Is it possible to place an RFID antenna on the bottom of a box, put an arbitrary amount of items with different shapes with ...
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1answer
66 views

RFID for angle encoding

Can RFID be used as an alternative to e.g. non contact magnetic encoders? Suppose a 150 mm diameter steel disk submersed in seawater subject to violent movement. Is it possible to put e.g. 30 passive ...
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1answer
44 views

Antenna polarization and antenna directivity are the same?

I'm working on an RFID project, and looking for information about the antennas that I have to use, I have the following doubt: Antenna polarization and antenna directiivity are the same? Thanks!
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1answer
286 views

SPI: Receiving bytes from slave

For a couple of days I have been learning about SPI and decided to give it a go with 2 small devices. DEVICE 1: Atmega328p (MASTER) DEVICE 2: MFRC522 (SLAVE) As far as I understand: master sets SS ...
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1answer
57 views

Why are inductively coupled RFID systems put in certain frequency bands when there are no EM waves used?

LF - 125 kHz HF - 13.56 MHz Those frequencies refer to the magnetic field that is used to induce a voltage in the transponder. Can the magnetic fields actually interfere with EM waves in the ...
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1answer
240 views

NFC/RFID device sending URL to NFC-enabled smartphone at 20-30cm

I am very new to this so please bear with me. I have read many questions but I haven't quite found a suitable one for what I would like to do. I would need a NFC/HF RFID device able to send an URL to ...
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3answers
124 views

RFID: Why is inductive coupling used instead of EM waves for LF and HF systems?

Is it because of antenna sizes? At 900 MHz a 1/2 dipole has a size of around 15 cm. That would be far higher for 125 kHz, so instead we use coils to power the transponder and use load modulation for ...
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1answer
40 views

How does electromagnetism factor into inductively coupled RFID systems

LF and HF RFID systems use inductive coupling to supply the tag with power. UHF RFID systems use antennas to send electromagnetic waves, the power supplied to the tag comes from the transmitted ...
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1answer
25 views

Variations in RFID USB Serial reader detection distance by connected device

I have a RFID reader that sends the TAG information over USB serial. I have had some troubles with it in a product where the detection success rate changes alot depending on what the USB RFID tag is ...
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3answers
5k views

Punch a hole into a RFID card (125khz)

So I have this 125khz RFID card and I would like to punch a hole in it so I can have a thin string go through it, making my card to be able to hang from my neck. Though I have no experience in ...
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1answer
29 views

RFID 13.56, can you include a tab in the data string?

I have tried to find the answer by googling but I can't find anything about it. On a normal barcode you can include a tab \t in the datastring making it possible ...
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2answers
55 views

Can UHF rfid pass thorugh few layers of clothes in a smart shopping system?

I am working on a smart shopping system and would like to know if a UHF rfid signal can pass through few layers of clothes in a bag as multiple clothes would be present in a bag and system has to ...
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1answer
324 views

Alternative wireless technology for passive RFID tags

I am working on a project where I have 3 boxes and a RFID reader (mfrc522) attached at the bottom of each box. I keep my wallet/keys/etc in these boxes and a LCD screen displays what is in each box ...
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2answers
4k views

Can you find what RFID frequency is used in a tag and then edit it? [closed]

A short background: my brother has membership at a gym that uses small RFID tags ("near field", I suppose, as you need to tap them against the spinning gate in order to open it) and after changing his ...
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1answer
79 views

SMPS Transformer affect RFID card

In my circuit, RFID card sometimes works sometimes not. it depends on how I put the card on RFID receiver. Usually it does not work when I put around the smps transformer. I guess SMPS transformer ...
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0answers
166 views

"MH" Markings on a MFRC522 RFID reader

I just bough 2 MFRC522 RFID reader from a different store. Both of them work well to read a standard 13.56 Mhz tags. However, one of them have "MH" marking while the other doesnt. The one with MH ...
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1answer
1k views

Increase range of 125khz RFID Reader

Currently the range for my 125khz RFID reader is about 4 centimeters. I have opened it like below: Is there any way to increase the range to around 10 to 20 centimeters? For example, increasing the ...
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1answer
839 views

Can I control/read an RFID reader with an Android device or do I have to put an Arduino board between the two? [closed]

I want to develop and Android app the reads RFID tags. I am wondering if I can control the RFID reader directly with an Android device or do I have to put an Arduino board between the two. The RFID ...
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2answers
281 views

Passive RFID tag - link between size of antenna and read range (detailed)?

It is often said that the smaller the tag, the shorter the read range. Could somebody explain more technically in terms of radio engineering? For instance: why the Hitachi's U chip cannot achieve a ...
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1answer
24 views

RFID Tag, Xbee or Bluetooth Module

I am just trying to detect if an object is within 7-10 feet from my phone. What device would you recommend? I don't care where it is or anything I just need a way of detecting that that device is at ...
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0answers
116 views

RFID reader antenna matching

I am trying to connect a RFID reader chip to an W3113 antenna on PCB. As said in datasheets, the antenna pin of the reader chip has internal 50 ohm impedance and antenna W3113 also has 50 ohm ...
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0answers
211 views

Servo sometimes freezes when used with another servo and MFRC522 RFID reader

I have looked, Googled and researched all over by now and I have not been able to find anyone experiencing a similar issue to mine, so I thought now would be the time to ask my own question on SE. ...
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1answer
397 views

Repairing an RFID antenna? [closed]

I have an RFID antenna that seems to be on a custom PCB. The issue I have is that the antenna on one side works fine, but the other side does not. I'm not sure if it is even possible or worthwhile to ...
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0answers
77 views

Proximity tracking using RFID

I would like to build a proximity tracking system. A a central unit small enough to fit on a key chain or necklace that would be able to detect as soon as a tagged object is farther away than a dozen ...
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1answer
334 views

RC522 board not working, red led is on

I have a RFID RC522 board that was working perfectly, until by mistake I tried to write it with a phone as if it was a RFID tag and now it stopped working, in the way that its led still turns on but ...
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1answer
58 views

What is a solution to representing bits physically? (on a cartridge, to be read by the cartridge holder... like a printer)

I am trying to recreate the sort of microchips that are on printer cartridges so that I can make cartridges that can have their data programmed and read? I only need to store 8 bits, so I was thinking ...
3
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1answer
4k views

On board 13.56MHz RFID antenna design

I recently stumbled upon a two-in-one NFC key designed by N-O-D-E and was astonished. Although its original purpose is for security, I love the idea of using tact ...
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1answer
897 views

AVR ATmega328 with DWM1000

I recently asked about this over in the Arduino stack, but it was a broad question, and I have made progress and narrowed down the issues. I have two Arduino Nano's, each attached to a DWM1000. This ...
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1answer
222 views

Protection against EMI for an RFID reader

I've designed a base board for a Velleman VMA405 (13.56 MHz) RFID reader based on MFRC522 IC. But, due to interference from the base board (I'm assuming the oscillator), the reading range is limited ...
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1answer
439 views

Anti-collision Capabilities of MFRC522

I'm a Computer Engineering student, and my full knowledge of RFIDs is limited to the research I have conducted thus far (mainly using this site). As such, there are still some general concerns I have ...
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2answers
51 views

How many clock impulses can a passive RFID get in 1 radio signal?Does it even have a CPU?

From what I've found so far, when scanning multiple passive RFID tags at once, collisions will occur so some collision avoidance algorithms like pure aloha and slotted aloha are probably used.What I ...
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1answer
334 views

Where is UNIQUE 125kHz protocol specified?

I am working on a RFID reader project and I can't find 125kHz UNIQUE tag specification (like listed in this TWN4 reader spec). I could easily find the datasheets for EM4100, EM4200, EM4102 tags. One ...
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4answers
596 views

RFID protective case metal selection

There are various RFID tags that are designed to work in close proximity to metal but generally they hope for free space or at least limited loading in close proximity. As a work around for RFID tag ...

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