Wednesday Jan 21, 2009

How Sun Spots fared in XTreme conditions

As I mentioned in my last blog, we had been to the KMTR Rain forest for a possible deployment solution using Sun SPOTs. Here is a brief accout of how Sun SPOTs actually fared in these XTreme conditions..

The Existing System:

ATREE has undertaken a pioneering canopy research program at KMTR which is opening a new world of ecological understanding.As a part of the project, they need to measure various environmental variables as temperature, light, rainfall, soil moisture, if possible CO2 etc.

Currently the parameters are measured using hobo data loggers developed by Onset in US from various parts of the forest, that could be ground, forest canopy, disturbed forests etc. The data loggers currently give readings at 1 hour interval for light, temperature and RH

Actual Deployment Place highlighted in Red

The Environmental Conditions:

1. Temperature Range:      8 - 38 Degree C

2. Humidity:                     15-100%

3. Rainfall Range:             1000-4500mm

Requirements: Hobo Datalogger circuit

Since they do long term monitoring at the site for vegetation, phenology and soil moisture levels the equipments need to run unattended for months together. The equipments should also be small, completely water proof - usually moisture levels are 100% for a large part of the year. Many dataloggers have failed due to moisture. Hence, a reliable, moisture resistant sensor network is needed which will measure the required parameters efficiently.

They deploy the data loggers on tree tops about  22 - 25 mt high. They periodically have to climb up trees and bring the dataloggers down. So, it would be really useful the system could send data down wirelessly if base station connected to the computer is in range.The data can then be stored in database and analyzed to generate reports. But theory sounds really good... What about practical deployment and feasibility? We analyzed many important aspects. Here is what we found...

Can Sun SPOTs help ?                                                                                                  The Data Logger Circuit

Issue I: How to protect the Sun SPOT in such hostile conditions?

                                 Box Open Box Closed

The environment where the actual deployment is to be made is very hostile.. The main problems are:

  • Humidity
  • Wind
  • Rain
  • Animals - specially monkeys.. One of the data logger was actually chewed away and destroyed by a Nilgiri Langoor


Sun SPOT and HOBO Together!                                                         Deployed on Tree Top

But the solution was already in place! They have developed a nice little box that keeps the data logger away from Rain and water splashings from sides. Also they lock it awat so that the animals cant get their hands on that. The device is suspended from the middle and slits are provided so that the temperature and moisture are not altered. 

Issue II: The accuracy of the data?

We had developed a prototype of the probable system for testing. The Sun SPOT was kept on the tree for 1 day and programmed to take 48 readings of light and temperature at intervals of 1 hour each. Later it would send the data to database through basestation.

The actual result was fantastic! We had placed the Sun SPOT besides the hobo data logger inside the box and the readings found were almost matching. The slight deviation of 0.5 units was completely acceptable.

Here is the actual comparison:

Readings with Data Logger:

From ATREEPics

Readings with Sun SPOT

From ATREEPics

Issue III:  Range of Sun SPOTs!

We did rigorous testing for the Range of the Sun SPOTs. And the results were fantastic again:

Height above sea level

Humidity

Elevation

Environment

Time

Range Found

1250 m

60 – 65 %

Horizontal

Clear Ground

09:20:00

70 m

1250 m

60 – 65 %

40 Degrees vertically Downwards

Some obstacles like shrubs and few trees

09:45:00

38 m

1300 m

75 – 80 %

Horizontal

Clear Ground but very windy

22:30:00

90 m

1200 m + 22 m on tree top

71.00%

Vertical

Inside dense forest with thick foliage between ground and tree top.

11:00:00

22 m but not very clear. We had to move about to get clear range.

20 m on tree top

75.00%

Vertical

Inside forest with little foliage between ground and tree top.

16:00:00

20m clear transmission found.



Dr T Ganesh (ATREE Scientist) and Us.                                       Last ditch Code Changes!

Conclusion  The project is ON! Cheers!!

About

I am the Sun Campus Ambassador for SRKNEC, India. Here I will blog about my college activities,and Sun's open source technologies like Netbeans, Opensolaris, Sun SPOTs etc..

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