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This study discusses the practical challenges faced during campaign-style deployments of wireless sensor networks (WSNs) in a tropical ecosystem in Quito, Ecuador. Conducted over 16 days with high data rates and limited power supply, the deployment focused on understanding soil respiration. Key issues included power cycling, sensor range limitations, and the need for on-the-fly data management. Lessons learned emphasize the maturity of WSN technology and the necessity for adaptable sensor configurations and real-time data access for researchers in the field.
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Experiences and Challenges in Campaign Style Deployments using Wireless Sensor Networks Jayant Gupchup†, Scott Pitz*, Douglas Carlson† , Chih-Han Chang*, Michael Bernard*, Andreas Terzis†, Alex Szalay±, Katalin Szlavecz* Department of Computer Science, Johns Hopkins University† Department of Physics and Astronomy, Johns Hopkins University± Department of Earth and Planetary Sciences, Johns Hopkins University*
Campaign Style Deployment Quito Jayant Gupchup
Requirements / Constraints Jayant Gupchup • No access to line power or internet • Collect data at a high rate (e.g. 30s) • Deployment order of days to weeks • Researchers require access to data in field
A Typical Sensor Network Stable Storage Gateway/ Basestation ……. 7 Ah
Differences / Challenges Power ~ 4W Jayant Gupchup • On-site decisions • Ad hoc hardware reconfigurations • Dealing with high data rates in the field (using a netbook) • Use of high power sensors • Vaisala CO2 sensors • Driven by a car battery
Deployment Details - I Jayant Gupchup • Location : Quito, Ecuador • Goal : Understand tropical soil respiration • Duration : 16 days
Deployment Details -II Jayant Gupchup • 30s Sampling Interval • Data retrieved over the air using a netbook • 20 Sampling locations • 12 Soil CO2 • 8 Soil Temperature & Moisture • Each CO2 Location • 3 depths (12 locations, 3 depths = 36 sensors) • Vaisala GMT 220 Series • CO2 Powered by 12 V / 45 Ah Car Battery
A CO2 Set-Up 3 m 3 m 3 m Jayant Gupchup
Under The Hood Antenna TelosB Mote Mote Battery CO2 Sensor Power Connector CO2 Sensors Jayant Gupchup
Power Consumption Jayant Gupchup • Lead acid car batteries 12V / 45Ah • Each battery serviced 9 CO2 sensors • Total current draw :1A • Lasted 36 hours after recharge
Power Cycling Motivation Jayant Gupchup • Batteries needed replacement/recharged every other day • Carried every other day for ~ 3 Km • 12V/40Ah car battery weighs 14Kg • Power Cycling! • Warm up time: 15 min
Some Data Power Loss Sensors lack range Jayant Gupchup
Ad Hoc Replacements Jayant Gupchup • At 11 locations, sensors lacked range to sense the phenomenon • Distribution of CO2 hardware • 10000 ppm : 26 • 20000 ppm : 12 • 30000 ppm : 3 • 100000 ppm : 3 • Researchers placed sensors initially • Reconfigured sensors if range was not good enough • Final data calibration requires accurate metadata: • sensor type and date of reconfiguration • Motivates need for self-Identifying sensors (Dallas 1-wire protocol)
High Data Rates Jayant Gupchup • Decisions in field are driven by the data • Researchers used netbook to download and view data • 10 days of 30s sampling: ~ 576000 rows • Spreadsheet and word processing software unable to handle this volume • Researchers stopped looking • Downsample: Provide low-resolution “view” in the field
System Performance Automated parts from existing system worked well. Jayant Gupchup
Conclusions Jayant Gupchup • WSN technology is mature enough to be driven by scientists • Challenges / Lessons Learned • Power cycling for high power sensors • Self-Identifying sensor design • Researchers require low-resolution data in field
Credit Jayant Gupchup NSF- MIRTHE, NSF- IDBR Microsoft Research Betty and Gordon Moore Foundation
Questions Jayant Gupchup