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RFID reader (abbreviation of radio frequency identification) is also known as "RFID reader", that is, radio frequency identification. It can automatically identify the target object and obtain relevant data through radio frequency identification signal without manual intervention. It can identify high-speed moving objects and multiple RFID tags at the same time, which is fast and convenient to operate. RFID readers and writers are fixed and handheld. Handheld RFID readers and desktop RFID writer include low frequency, high frequency, UHF, active, etc.

What are the components of RFID reader

A typical RFID reader terminal is generally composed of antenna, RF interface module and logic control module.

1. RFID antenna

RFID reader is a transmitting and receiving device, which is mainly responsible for converting the current signal in the reader into RF carrier signal and sending it to, or receiving the RF carrier signal sent by the tag and converting it into current signal. The antenna of the reader can be external or built-in. The design of the antenna is very important for the working performance of the reader, for the rfid tags, Its working energy is provided by the antenna of the reader.

2. RFID reader / writer RF interface module

The interface module of RFID reader mainly includes transmitter, RF receiver, and so on. The module is not only the RF front end of the reader, but also the key part affecting the cost of the reader. It is mainly responsible for transmitting and receiving. The modulation circuit is responsible for modulating the signal to be sent to and then sending it; The demodulation circuit is responsible for amplifying the signal sent by the demodulation tag; The clock generator is responsible for the normal operation of the clock generation system.

3. Logic control module of reader writer

The module of the reader / writer is the control center and intelligent unit of the whole reader / writer. It is the "brain" of the reader / writer. When the reader / writer works, the logic control module sends instructions, and the interface module makes different operations according to different instructions. It mainly includes,, and application interfaces. Microcontroller can complete signal encoding and decoding, data encryption and decryption and anti-collision algorithm; The storage unit is responsible for storing some programs and data; The application interface is responsible for input or output communication with.

Next, take the band reader as an example to introduce in detail how the RF module of the reader works. The RF module can be divided into two parts: transmitting and receiving. The transmitting circuit of the reader / writer is mainly composed of (mixer), (DAC), (attenuator), variable amplifier (VGA), (power splitter), (filter), and (PA). The working process of the launching part is as follows:

(1) The reader controls to generate a signal with a frequency of 860-96omhz, and then transmits the signal to the;

(2) The power distributor divides the signal to be transmitted into two parts, one part is sent to the receiving circuit as the signal source when the receiving signal is in progress, and the other way is passed first and then sent to the mixer;

(3) By mixing, the amplitude and phase of the carrier signal transmitted from the control of the reader are changed, and then transmitted to the receiver after passing through the variable gain (VGA) and RF filter;

(4) The reader automatically adjusts the gain of the transmitted signal according to the actual situation, then amplifies it, and finally transmits it to the reader antenna for transmission. Here, the function of circulator is to isolate the signal received by the reader antenna from the transmitted signal to avoid.

The receiving part of the reader / writer mainly includes (ADC) and the work flow of the receiving part is:

(1) The signal transmitted by the tag through backscattering usually has a relatively small power. It will first enter the circulator to separate from the signal transmitted by the reader and avoid co frequency interference. After passing through the RF filter, it enters the power distributor, and the signal from here is divided into two channels;

(2) The non carrier of the self transmitting line is used as the signal of the receiving line to generate two channels, and the difference between the two reference signals is 90;

(3) The two reference signals and the two signals separated from the first step generate two signals, and then return to the signal processing unit of the reader for correlation processing after respective and.

Main functions of RFID reader

The reason why RFID reader is very important is determined by its function. Its main functions are as follows:

① Communication with: the most common is to read the label. This function requires a reliable software algorithm to ensure security and reliability. In addition to reading, it is sometimes necessary to write the label, so that the label can be produced in batch, and the user can write the label according to his own needs.

② Energy supply to the tag: when the tag is passive or semi passive, the reader / writer needs to provide energy to activate the electronic tag around the field; The range that can be reached by the RF site of the reader is mainly determined by the size of the reader and the size of the reader. The size of the antenna is mainly considered according to the application requirements, and the output power has different regulations in different countries and regions.

③ Realize the communication with computer network: this function is also very important. The reader and writer can use some interfaces to realize the communication with the upper computer and provide some necessary information to the upper computer.

④ Realize multi label identification: the reader can correctly identify multiple labels within its working range.

⑤ Realize moving target recognition: the reader can recognize not only stationary objects, but also moving objects.

⑥ Realize error message prompt: for some errors generated in the recognition process, the reader and writer can send some prompts.

⑦ For the tag, the reader can read the battery information of the active tag, such as the total power of the battery, the remaining power, etc.