Application Requirements What to measure? Acceleration in 3- axis of motion Frequency components of interest 0.25-20Hz How long to measure? 40 sec of total vibration during and after train’s passage Time Synchronization Need accuracy of 5ms
Existing Techniques Visual inspection Mostly wired solutions Equipment is bulky and very expensive Large setup time (few days) for short-term monitoring Few wireless solutions Proprietary non scalable solutions Wisden (USC) Golden-gate bridge (UCB) BriMon
Existing Approaches GSM Data Transmission (Data) Solar Panels (Power) GPS (Time Synchronization) Star Topology (head node) 3 1 2 4 5 6
Star Networks Central base-station communicates directly to sensor nodes - Generally mains powered. All routes are ‘linear’ where each node only has one possible communication path. The failure of an individual link means that information is lost. Generally requires site surveys and link-level configuration. Each node must be positioned correctly and each point-to-point link tuned for maximum reliability.
Mesh Networks Full-mesh networks provide fully redundant routing to the edge of the network. Increased reliability, easy network installation and long-term predictability. Every device has the same routing capabilities. Lower power consumption. True self-organising and self-healing without constraints imposed by device type and architecture. Easy network expansion.
Wireless Mesh Network (TSMP) Time Synchronized Mesh Protocol (TSMP) >99.9% reliability Lowest power per delivered packet
Installation (Less work, Less wire,Less conduit…) No Site Survey Installed Like a Wired Device Commissioned Like a Wired Device Operates Like a Wired Device
Maintenance redictive and timely P indication of failure trends Send Maintenance elivers accurate and D ONCE to repair … actionable data more effectively than monthly snapshots … Not 20 TIMES to CHECK
25 Radio Performance 20 X With software: cc2420 10 years D cellIRX (mA) 15 X 10 cc1000 With software: 5 10 years coin cell Molnar 04 (0.4mA) Cook 06 (300 µW) X X X Otis 05 (0.4mA) 100k 300k Bit rate (bps) 200k