UHF RFID reader
receivers also require transmitters to send unmodulated carriers when
operating. Receivers include tag reflection signals, antenna noise,
environmental reflections, direct transmitter coupling, and the
receiver's own noise. Now if we want to stably read a distance of 10
meters, and let RFID readers
achieve 100% recognition rate and be able to adapt to changes in the
weather and the environment, the effect of reading is better than that
of common products. What should I do?
Practice: Processing Baseband Digital Signals
Oversampling and filtering. Oversampling can reduce the power of quantization noise in the effective bandwidth and improve the signal-to-noise ratio, which is equivalent to increasing the resolution of the ADC. The data obtained by oversampling can be extracted by the CIC filter, so that the data rate can be returned to the normal level and then cascaded. FIR filters are band-pass filtered to further reduce noise power and improve signal-to-noise ratio.
DC offset correction. Simply through the capacitive AC coupling method can filter out the DC part of the signal to reduce the DC offset interference. This method is the simplest structure, the lowest cost, and thus the most widely used.
Data decoding. The baseband data decoding method is divided into zero-crossing detection and coherent detection. Zero-crossing detection works by setting a threshold. Each data sample in the data buffer is compared with the median value. Because this method is simple and easy to implement, even a comparator can be used to implement the decision, which is widely used in Ethernet RFID reader products.
The advantage of RFID technology is more reflected in the group reading, and the core of this advantage lies in the anti-collision algorithm. You can choose a good product at the time of purchase. A good process design and some necessary fault-tolerance mechanisms will affect The read/write performance of an RFID product also involves RFID's 100% recognition rate in practical applications.
Oversampling and filtering. Oversampling can reduce the power of quantization noise in the effective bandwidth and improve the signal-to-noise ratio, which is equivalent to increasing the resolution of the ADC. The data obtained by oversampling can be extracted by the CIC filter, so that the data rate can be returned to the normal level and then cascaded. FIR filters are band-pass filtered to further reduce noise power and improve signal-to-noise ratio.
DC offset correction. Simply through the capacitive AC coupling method can filter out the DC part of the signal to reduce the DC offset interference. This method is the simplest structure, the lowest cost, and thus the most widely used.
Data decoding. The baseband data decoding method is divided into zero-crossing detection and coherent detection. Zero-crossing detection works by setting a threshold. Each data sample in the data buffer is compared with the median value. Because this method is simple and easy to implement, even a comparator can be used to implement the decision, which is widely used in Ethernet RFID reader products.
The advantage of RFID technology is more reflected in the group reading, and the core of this advantage lies in the anti-collision algorithm. You can choose a good product at the time of purchase. A good process design and some necessary fault-tolerance mechanisms will affect The read/write performance of an RFID product also involves RFID's 100% recognition rate in practical applications.
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