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Wireless Sea Measurement
UnitA Plan for Aarne Halme Project
Juha VanhalakkaErkka Mutanen
ContentsO Project SpecificationO XBee Radio ModuleO Other ComponentsO Concept ArtO SWOT AnalysisO Seabed MountingO Arduino EnvironO CodeO CostsO Project Schedule
Project SpecificationO Implement a prototype of a wireless
sea measuring station for professor Aarne Halme’s summer cottage
O Use wireless connectivity to integrate to existing home automation system (ThereGate Linux server)
O Keep things small and energy-independent but also as cheap as possible
O Prototype finished in December 2013
Block Diagram
XBee-PRO Radio Module
O Operates at 2.4 GHz ISM band (ZigBee)
O 100 / 1500 m indoor/outdoor op. radius,
O TX current 100-215 mA, RX current 50 mA
O Link data rate 250 kbps (IEEE 802.15.4)
O 5 x 10bit AD converters
Measurement CircuitsO Voltage splitting
circuit for pressure sensor and power monitoring
O Case temperaturemeasurement
Measurement Circuits II
O PT100 (R10) measurement done with 2 differential amplifier
Power Management
O Battery keeps the Sea Unit running during night time
O High efficient chopper converters used
Other Components
Embedded Antenna (OPTIONAL)O 2.4GHz puck antennaO Fully water-proof
Multicomp Solar PanelO 800 mW polycrystal panelO Weather-proof with aluminum
framesO Voltage output > radio circuit
voltage
CONCEPT ART
Project Analysis
Strengths• Easy to implement• Low-cost installation and
maintenance• Automated data history graphs
Weaknesses• Robustness to weather?• Powered by sun, need sunlight• Removal out of water during
winter
Opportunities• No players in consumer market• New ZigBee technology• Extendable for wave size
tracking
Threats• Winter conditions• Corrosion
Prototype
Seabed MountingO Many possibilities:
1. Mounting near pier on dedicated pole2. Mounting on pier (measurement under quay)3. Mounting near pier on non-dedicated pole
O Aluminum tube (pole)
O Commercial metal shoes with spikes for underwater attaching
O Not available on rock bottom
O Prefer wood constructs over metal (Finnish style)
Arduino EnvironO Open-source physical computing
platformO Microcontroller board +
development environO Based on ATMEL’s ATMega
processorsO Objective-C “Processing” language
CodeO Device pairing and routingO Radio RX/TX loop codeO Sleep cycle codeO Request for resend code
O Measurement filtering (OPTIONAL)O Measurement pre-processing
(OPTIONAL)
CostsO ZigBee XBee RF chip 40€O Solar panels 8€ x2O Hydrostatic pressure sensor
WIKA LH-10 0€ (540€)O Resistors, switches, LEDs,
optic fiber 5€O Battery pack 5€O Sea bed mount 60€O Casing 40€
TOTAL costs 166€
Project ScheduleO Project Plan 25.09.O Progress Report 30.10.
+ electronics ready, code runningO Demo A 20.11.
+ casing ready, code readyO Demo B 27.11.
+ mounting prototype doneO Documentation done 10.12.
End
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