Demodulation method for ultrahigh-frequency RFID signal in low signal to noise ratio
A technology with low signal-to-noise ratio and demodulation method, applied in the near-field transmission system, inductive record carrier, transmission system and other directions of radio frequency identification system, can solve the problems of difficult demodulation, long receiving distance, complex electromagnetic environment, etc. The effect of strong applicability, small calculation amount, and few signal sample points
Active Publication Date: 2018-07-10
NO 30 INST OF CHINA ELECTRONIC TECH GRP CORP
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However, due to the long receiving distance and complex electromagnetic environment, and because the energy signal of the reader and the tag signal have the same transmission frequency, and are affected by factors such as multipath effects and environmental interference, it is difficult to correctly demodulate based on traditional methods
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[0021] The invention proposes a demodulation method of ultra-high frequency RFID signals under low signal-to-noise ratio. The core idea is to use the adaptive noise reduction algorithm and the optimized blind synchronous demodulation implementation structure, so it has good performance. In the preprocessing process, it is first necessary to perform quadrature down-conversion on the received signal. In order to reduce noise interference, band-pass filter processing is added, which can reduce the signal-to-noise ratio loss caused by nonlinear processing in subsequent operations to a certain extent. but from figure 2 It can be seen from the figure that the modulation waveform of the tag signal at this time is "suspended" on the undulating envelope of the DC component and the residual carrier signal. In order to restore the baseband modulation waveform of the signal, it is necessary to remove these interferences and further reduce the influence of noise, otherwise the RFID infor...
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The invention discloses a demodulation method for an ultrahigh-frequency RFID signal in a low signal to noise ratio. The method comprises the following steps that 1) a change envelop curve of the RFIDsignal is fit in an adaptive fitting based preprocessing method, and interference is removed to obtain a baseband signal; and 2) waveform of the RFID baseband signal is matched, frame head filteringoutput is combined with feedback information to carry out aligning, the waveform is matched via 1 and 0 coding, and matching output is decided in the optimal sampling point to obtain a final demodulation result. The method is high in anti-noise and anti-interference performance, can adapt to severe electromagnetic environments, needs few signal sample points, is low in operand, and has a high practical engineering value for an RFID signal monitoring system, a cognitive RF reception system, a traffic signal control system and the like. The modulation method is excellent in performance and highin applicability.
Description
technical field [0001] The invention relates to a demodulation method for ultra-high frequency RFID signals under low signal-to-noise ratio. Background technique [0002] Radio Frequency Identification (RFID) is an automatic identification technology, which uses radio frequency signals and spatial coupling transmission characteristics to realize automatic identification of objects. With the development of wireless communication and Internet of Things research, RFID technology has risen rapidly in various fields, forming a huge industrial chain. The typical working frequency of UHF RFID signal mainly includes 433MHz, 860MHz to 960MHz, etc. Its data transmission rate is high, the anti-collision mechanism is relatively complete, and it can read a large number of tags at the same time. It has been used in intelligent transportation, intelligent manufacturing, and logistics. , identification and many other aspects, more and more attention has been paid. Based on the RFID system...
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IPC IPC(8): G06K7/10G06K7/00H04B5/00
CPCG06K7/0008G06K7/10297H04B5/77
Inventor 熊刚饶志宏张晓康荣保刘丹
Owner NO 30 INST OF CHINA ELECTRONIC TECH GRP CORP