SELENESafe Exploration for Lunar Environments: Navigation Experts |
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Overview The proposed system encompasses two predominate link budgets, the link between the astronaut and the lander as well as the link between the astronaut and scattered RFID tags. From these budgets the maximum communication speed of the astronaut and the maximum distance between the astronaut and any RFID tag can be calculated. In order to establish these budgets, it is necessary to pin down several parameters of the system. The antenna parameters are taken from the extrapolated results of the measured prototype antenna, while the power is chosen to be -5dbW (well below the guidelines set by OSHA). Using these values, as well as the calculated losses necessary (details can be found in the full pdf report), the link budget is completed and illustrated in Table 1. Error Correction and Coding To maximize the communication speed for the link between the astronaut and the lunar lander, (63,61) Reed-Solomon code as well as ½ Rate Turbo codes were employed. Using these codes and the base C/N value of 6.3 dB, a final bit rate of 1.1092Mbps was achieved. The block diagram for the physical link between the astronaut and the lunar lander is shown below.
RFID Link Budget Based on the required power for power-up of the RFID tags the maximum distance between astronaut and RFID tag is 2.1 m. In order to overcome the interferences of multiple RFID tags, a novel RFID reader architecture has been designed and is outlined in the full pdf report. The block diagram of the RFID reader is shown below:
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