UHF RFID reader frequency offset estimation and frame synchronization method and device
A technology of frequency offset estimation and reader-writer, applied in the field of digital communication, can solve problems such as noise interference, short synchronization code of frame header, and low accuracy
Active Publication Date: 2014-06-25
BEIJING CEC HUADA ELECTRONIC DESIGN CO LTD
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[0029] Based on the content of the present invention, it is applied to the UHF RFID reader device conforming to the ISO18000-6C protocol to perform frequency offset estimation & frame synchronization process on the tag return signal, and the specific implementation steps are given. The UHF RFID reader baseband receiver uses 32 times the code rate of the RFID reverse link as the clock for sampling the tag baseband signal, and implements the frequency offset estimation & frame synchronization of the tag return signal by the reader baseband as an example. Frequency Offset Estimation & Frame Synchronization Process Dependent Figure 5 and the abstract accompanying drawings are described as follows:
[0030] 1. The reader baseband receiver samples the tag baseband signal at a rate 32 times the RFID reverse link code rate.
[0031] 2. Set the initial synchronization threshold and synchronization time.
[0032] 3. Each correlator of the parallel correlator array performs a cross-co...
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The invention provides a method and a device for carrying out frequency offset estimation and frame synchronization on tag baseband signals in UHF RFID reader equipment. According to the method, cross correlation operation is carried out on received signals and local sequences of parallel correlators; if the maximum value of the correlation values outputted by the parallel correlator arrays at certain time is larger than a synchronous threshold, the synchronous time is updated to the time and the synchronous threshold is updated to multiply the maximum correlation value by the settable threshold adjusting coefficient (the adjusting coefficient is between one to two), when the fact that the correlation value obtained though cross correlation operation between the received signals and local sequences of parallel correlator arrays is larger than the synchronous threshold does not exist at certain time, frequency offset estimation and frame synchronization are indicated to be finished successfully, and code-frequency offset of tag return data is the frequency offset corresponding to the correlator of the maximum correlation value obtained in the parallel correlator arrays at the synchronous time.
Description
Technical field: [0001] A method and device for frequency offset estimation and frame synchronization of tag return signals used in UHF RFID reader-writer equipment, which belong to the technical field of digital communication. Background technique: [0002] Radio frequency identification technology (RFID) is a non-contact automatic identification technology, and its basic principle is to use the transmission characteristics of radio frequency signal space coupling to realize automatic identification. [0003] RFID systems generally consist of two parts, namely tags and reader devices. In the actual application of RFID, the tag is attached to the surface of the object to be identified. When the tag enters the readable range of the reader device, the reader realizes the tag information through steps such as AGC adjustment, frequency offset estimation & frame synchronization and FM0 decoding. read. [0004] Since the RFID tag needs to meet the requirements of low cost and lo...
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IPC IPC(8): H04L25/02H04L25/03G06K17/00
Inventor 邹锦芝徐海军邬泳廖峰包玉华李鼎
Owner BEIJING CEC HUADA ELECTRONIC DESIGN CO LTD