analysis of an omni-directional narrowband ultrasonic receiver and css-based broadband transmission
Ultrasound (US) based Cricket indoor location system has limited range when the transmitter and receiver motes are not in the line-of-sight (LOS) positions. It uses narrowband US transducers which are unidirectional and require tilting of the motes in order to improve the signal reception quality. The main focus of this work is to improve the ranging distance of the ultrasound based sensor motes with an objective of successfully deploying in harsh environments where the prime challenge is that of gracefully sustaining the signal characteristics for the purpose of distance estimation. We implement and provide an analysis of two different techniques with respect to the original Cricket: 1) Omni-directional receiver: A dodecahedron arrangement of an array of 3 US transducers. 2) Chirp spread spectrum based broadband transmission scheme and signal correlation technique.
omni-directional receiver chirp spread spectrum