Passive transceiving common-frequency RFID system with triaxial closed-loop self-tuning function

Abstract

The invention discloses a passive transceiving common-frequency RFID system with a triaxial closed-loop self-tuning function. According to the passive transceiving common-frequency RFID system, a triaxial tuning network is inserted in a space between a directional device of a reader-writer and a high-frequency switch. The triaxial tuning network comprises a basic fixed capacitor, an intermediate digital tuning capacitor, an input digital tuning capacitor and an output digital tuning capacitor. Tuning parameter table items are established automatically corresponding to a currently selected antenna port for all working frequency points in a working frequency band of the reader-writer so as to form a tuning parameter table bound with the antenna port and the working frequency band. In the continuous radiation process of an antenna connected with the antenna port of the reader-writer, the reader-writer reflects power detection in real time, dynamically modifies the tuning parameter table, and compensates for environmental changes within the radiation range of the antenna in real time. For the purpose of prolonging a label reading distance, improving the transmitting power of the reader-writer and restraining forward leakage and forward reflection of the reader-writer at the same time, the triaxial tuning network is used for lowering the forward reflection of the reader-writer. The method is simple in circuit and debugging.

Description

technical field [0001] The invention relates to a passive transceiving and co-frequency RFID system, in particular to a passive transceiving and co-frequency RFID reader-writer antenna connection environment three-axis closed-loop self-tuning system. Background technique [0002] Conventional passive reflective RFID systems are mainly composed of tags and readers. The tags provide power only by receiving or sensing electromagnetic energy, and at the same time transmit data to the readers by modulating the load characteristics of the antenna or coil. Therefore, the reader belongs to the same-frequency RFID reader. At the same time, since the tag needs to continuously supply electromagnetic energy to the reader, the reader needs to continuously send a single carrier to the tag while receiving the data returned by the tag, and the center frequency of the tag's returned signal is consistent with the single carrier frequency. [0003] In order to compensate for the forward free ...

AI Technical Summary

Problems solved by technology

Such a high DC deviation saturates the amplifier stages after the mixer and cannot amplify the useful signal

On the other hand, the high-frequency switch used by the reader to select the antenna port and the standing wave ratio of the antenna connected to the antenna port are limited, and the single carrier wave reflected by the reader from the forward transmitting branch to the backward receiving branch through the antenna is as high as 10dBm ~15dBm, known as the forward reflection of the reader, before entering the mixer of the receiver, the mixer has been saturated, and the baseband signal cannot be demodulated

[0004] In order to increase the reading distance of the tag, increase the transmission power of the reader, and at the same time suppress the forward leakage and forward reflection of the reader, the carrier cancellation method is often used, and the carrier cancellation network is inserted at the front end of the reader receiver. The circuit involved in this method complex, difficult to debug

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