(1) are irrelevant to the distance d, we can lump the three offsets into a single variable δ i for each channel i. However, for Impinj R420, a commodity RFID reader, the phase offset between two adjacent channels that it hops to is not a constant, even though the distance d remains the same, as found in our experimental studies. Once the tag is attached on the human chest, the respiration could be monitored by the variation of d. From the equation we find that the tag-to-reader distance ( d) can be reflected by the sampled phase. Where d is the total distance from the reader’s antenna to the tag and then back to the reader antenna, f i is the frequency of channel i, c is a constant representing the speed of light, and δ T, δ R, and δ Tag are the phase offsets caused by the transmitter circuit, the receiver circuit, and the tag’s reflection characteristics, respectively. #Rfid cards and reader images mod#(1) ϕ f i d = mod 2 π f i d c + δ T + δ R + δ Tag 2 π , Other similar platforms based on inkjet printing on paper substrates have been presented. The best known example is the wireless ID and sensing platform from Intel Research Seattle. In the last few years, some platforms based on microcontrollers that emulate the behavior of passive UHF EPC Gen2 tags have been presented. These electrical changes are translated in changes in the RFID signal. The electrical parameters of the materials (such as permittivity and conductivity) are changed by the physical parameters. RFID-enabled sensors are integrated with materials that are sensitive to physical parameters, for instance water-absorbing materials for humidity sensors and carbon nanostructures for gas sensors. It is also possible to integrate RFID systems in conventional WSNs, as shown in. #Rfid cards and reader images Bluetooth#The architecture of RFID systems is also simpler than other systems such as bluetooth LE or ZigBee (see section 1.2.1), because the sensor tags do not require dedicated transceivers. The cost of RFID tags can be very low when using low-cost substrates and inkjet printing technology. RFID systems also have a several advantages for WSNs in smart homes or smart cities applications. As an example, in, an RFID-enabled sensor tag is embedded in cork wine bottle stoppers to monitor their temperature. Accelerometers can also be used in fragile products in order to detect hits or bad package handling. The customer, as well as the seller and logistics companies, can determine the temperature range of the item from its production to its final destination. One typical application for RFID-enabled wireless sensors is monitoring the cold chain in perishable products. Also, even though ZigBee or bluetooth can offer faster absolute data rates, the communication with RFID is established faster because the tag does not need to associate and authenticate with the reader at the beginning. In addition, RFID systems have less complicated protocols and data frames than ZigBee or Bluetooth, for instance. Adding sensing capabilities to RFID permits possibilities beyond what barcode systems offer. This link can also be exploited to collect data from a sensor connected to or embedded into the tag. The RFID reader uses a wireless communication link when it retrieves the ID from one or several tags. Ramon Villarino, in RFID and Wireless Sensors Using Ultra-Wideband Technology, 2016 1.2.2 RFID-enabled wireless sensors The same happened for another 60 styles, which were taken to the fitting room but remained unsold.Īngel Ramos. Probably such items did not fully meet the customers’ expectations. A further 708 styles had ratios between number of sales and number of try-ons ranging from 100 to 0%. Another 328 styles showed a ratio between number of sales and number of try-ons higher than 100%, meaning that more were sold than were tried on. These styles were mainly accessories and could be considered as ‘self-selling’ items, since they did not require assistance from sales associates nor proper try-ons. The analysis of the data collected indicated that 116 styles that have never been tried on were sold during the season. Before RFID deployment, such data were obviously unavailable. This deployment made it possible to determine which items were selected by the customers, where those items were tried on, and how many try-ons they underwent. The RFID reader installed in the fitting rooms was equipped with a near-field antennae and put in continuous-read mode. Bertolini, in Fashion Supply Chain Management Using Radio Frequency Identification (Rfid)Technologies, 2014 Fitting
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