4. 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
5. 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
6. Existing Approaches
GSM Data Transmission (Data)
Solar Panels (Power)
GPS (Time Synchronization)
Star Topology (head node)
3
1
2
4
5
6
7. 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.
8. 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.
9. Wireless Mesh Network (TSMP)
Time Synchronized Mesh Protocol
(TSMP)
>99.9% reliability
Lowest power per delivered packet
16. 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
17. 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
18. 25
Radio Performance
20 X With software:
cc2420
10 years D cell
IRX (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