RFID readers are an essential component of any RF identification & tracking system. They act as the middlemen between different components of the system and the user. But what exactly is a reader and how do they work with the rest of the Rf system? That is exactly what we will discuss today.
Radio Frequency Identification (also known as RFID) is a type of data collection technology that works by using radio signals. Specifically, it is a type of AIDC (Automatic Identification & Data Collection); these are systems that can identify assets/personnel based on inputs like facial features, physical shapes, encoded radio signals, etc; and collect data about the movement and use of these assets/personnel.
In a typical RF system, four major components are required to perform nominally. These are – Tags, Readers, Antennas, and Software. A tag acts like a transponder, it receives an interrogation signal from the reader. Once it does that, it will use either signal backscattering or electromagnetic induction to send back a carrier wave with the data stored inside its memory on it. The reader and the antennas work in harmony as one unit. The reader generates a digital signal that is broadcasted by the antenna, this signal creates a field of influence around the antennas called the interrogation zone. The antenna then receives the reflected signals from any tag within this field, converts it into a digital signal, and sends it to the reader.
Lastly, the software; in any kind of hardware operation, we need software to allow the users to interact with the hardware components. Most businesses prefer to get a developer to create them custom software, tailored to work best with their operations.
What is an RFID Reader?
As mentioned above, and as the name suggests, a reader such as the Zebra FX9600 is an essential component of any RFID system. It is responsible for communicating with the tags and the computer/database interface. A typical reader contains an RFID chip inside it, it’s a type of IC (integrated circuit) that is programmed to do two functions, namely – generate digital signals (interrogation signal) of a particular frequency and encode/decode RFID signals.
How Does an RFID Reader Works?
Readers require an antenna to perform their functions, these antennas can be integrated inside the reader or be attachable through connecting points. A reader will first generate an interrogation signal; it is a digital signal that is meant to activate the tags. Then send that signal to the antenna, which will broadcast it in the form of electromagnetic radiation (radio waves). This signal broadcast creates a field of influence around the antennas, known as the interrogation zone. The interrogation zone can be divided into two separate sections, let’s discuss in brief about them:
Different Zones of a Radio Broadcast Field
As mentioned above, a radio field can be divided into two parts, namely – Near Field, and Far Field. Near-Field refers to the initial zone around an antenna, the length/boundary of a near-field is almost as much as 1/16 of the wavelength of the signal. This region is also known as the inductive field, as it is capable of inducing electric charge in conductors within it.
Far Field refers to the effective broadcast zone just after the near field. The signals within this zone are not powerful enough to have an inductive effect. Therefore, RF tags within this zone must rely on signal backscattering to communicate. Backscattering refers to the phenomenon where a metallic surface bounces back incoming electromagnetic signals in different angles; scattering the signal in the opposite direction.
When tags enter the interrogation zone, they use either inductive coupling or radiative coupling (backscattering) to send a signal back toward the antennas. The antennas receive these signals and convert them into electronic/digital signals and send them to the reader via cables. Once they reach the reader, it decodes the signal and sends it to the computer. The software in the computer converts the signals into a readable format and shows the data on the interface.
Essentially, the reader acts as a messenger between the item/tag and the system/user. It facilitates communication between the two endpoints of an asset identification and tracking system.
Types of RFID Readers
There are a variety of RFID readers available in the market, from integrated, fixed mounted to handheld, Wi-Fi, etc. However, here we will discuss the types of readers based on their independent functionality. Based on this criterion, we can divide RFID readers into two classes, namely: Active Readers, and Passive Readers.
(A). Active Readers
These are the most common type of readers available in the market, since readers are generally not needed to be mobile, so they can be easily connected via cables. As the name suggests, an active reader does not require an outer influence to begin performing its function. This is because they are connected to a power source, meaning that they can generate their interrogation signals using this power. Normal fixed-mounted readers & handheld readers are mostly active in nature.
(B). Passive Readers
On the other hand, a passive technology/system requires an outside influence to start working. Passive readers are not connected to an energy source to power up. Hence, they cannot broadcast their signals too. Instead, they rely on the signals coming from the tags. These systems require active tags to operate, as at least one end of the system must be capable of broadcasting powerful signals. When the reader is inside the broadcasting range of the active tag, it uses its antennas to receive the signal and convert it into a digital signal.
Frequently Asked Questions
Q1. How does RFID work without power?
There are two ways where an RFID tag work without a power source, namely: Inductive Coupling, and Radiative Coupling. When a tag is within the near field (inductive field), the signals induce an electrical charge within the tag powering it up. The tag uses this energy to broadcast a signal.
On the other hand, when the tag is inside the far field, it uses its antenna to bounce back the reader’s signal using backscattering. This reflected signal acts as a carrier wave for the information/data stored in the RF tags.
Q2. What are the 2 disadvantages of RFID?
Like any technology, even RFID has its disadvantages-
• RFID technology is prone to signal attenuation and disruption from metal surfaces and liquids.
• A big disadvantage of RFID over other forms of AIDC technology is cost. For example, RF components can cost as much as ten times more than barcodes.
Q3. What is the difference between barcodes and RFID?
Although they both are types of AIDC technologies, i.e., Automatic Identification & Data Collection. However, they have remarkable differences between them. Barcodes work as a visual data storage medium. Meaning, that it stores data in a visual format, in the form of bards and patterns.
On the other hand, RFID systems store data in digital format & communicate data via radio signals.
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