Radio environment Sample Clauses

Radio environment. This section summarizes the results from tests performed to investigate the electromagnetic en- vironment at a conveyor belt transporting iron-ore pellets at “malmhamnen” in Lulea˚ during early 2015. The tests were conducted at the location shown in Fig. 3, the belt going up to “siktfickan”. • A Rohde&Schwarz ESPI Test Receiver used for measurements on the electromagnetic environment. It was switched between an EMCO 6512 loop antenna for the 50 kHz-30 MHz band and an AARONIA Hyperlog antenna for measurements between 800 MHz and 6 GHz. • A ▇▇▇▇▇ B4200 125 kHz RFID-reader provided by Electrotech. This reader was modified to enable measurement of the excitation and the resulting coil voltage. It was also modified by Electrotech to account for that the coil antennas have inductances different from what the reader was designed for. • A Ettus Research N210 digital sampler used for digitizing the output signals from the RFID- reader. In addition, a portable magnetic field probe (Fig. 5) using the same type of 3D coil anten- nas intended for direction-insensitive pellet-size RFID-tags was built and used for measuring the magnetic field generated by the coil antenna. • Magnetic field strength at 10 positions along the length of the conveyor belt. • Magnetic field strength at 9 positions over the belt, in the approximate volume where pellets can be expected. • Responses from both large and small RFID tags were recorded using the digital sampler for 9 positions (only the large tags) within the volume where pellets can be expected. The response was detected in terms of the cross-correlation between the known response and the measured complex ratio between coil voltage and excitation (to suppress some of the noise in the excitation signal). • Ambient magnetic field strength in the 50 kHz-30 MHz band and ambient electromagnetic field strength in the 800 MHz-6 GHz band. These measurements were performed both with the conveyor belt stationary and with the belt running without pellets. • Modulation of the received signal due to motion of magnetic material or the antenna. This test was performed with the belt stationary, and in motion both with and without pellets. Figure 5: The 3-dimensional magnetic field probe used for measuring the magnetic field in the vicinity of the RFID antenna. 10−4 10−5 Field strength (T) 10−6 10−7 30.9 dB and 37.3 dB with an average of 33.5 dB. As the field was believed to be too weak to power the small tags only one test was performed at the pos...