It has been a while since our last News Update but we have been very busy. We have re-released our general data/dendrometer device management platform so if you haven’t taken a look yet, head over to the EcoSensorNetwork if interested.
Secondly, we have finished the first iteration of the WiFi version of the dendrometer. This version of the dendrometer directly connects to your WiFi point and uploads data directly to the web. This means no gateway is required. The trade-off, at least in this first version, is battery life and proximity to your WiFi router.
Work on battery efficiency will continue on both the WiFi and XBee versions of the dendrometer.
We are also looking forward to the beginning of spring and the first real signs of water movement within the trees. At this point, we have noticed tree stems are actually increasing in size during the day, the opposite of what we see during the growing season. If there is no growth or water movement, could this be just thermal expansion?
On the Technical Side
The new Wifi version of the dendrometer utilizes the RX-XV WiFly module by Roving Networks. This is certainly a cool device. It sports a full on web/ftp server and you communicate with the device directly. Simply boot the device in configuration mode and it creates its own WiFi network. Connect to that network and you can configure the device for your needs. More details and instructions will be posted to tree.bio shortly.
School has started and a number of educators are asking about how they can use the dendrometer sensors in their STEM programs. Moreover, many are interested in the idea of the dendrometer kit. The kit would include all components, instructions and access to software needed to build their own dendrometers. If you are interested in obtaining the dendrometer kit or have any questions, please send us an email!
Much is happening in development. Two big steps were made. First of all, we have reduced the power consumption of our main design from 27 mAh to 10.6! This means that our standard 4,000 mAh battery needs to be replaced after 15 days instead of 6. Also, we are checking out the use of a 12,000 mAh battery that will fit in the case. With this setup, we could expect about 47 days!
If you are wondering what happened to the D-Cell batteries, we still are experimenting with them, but it seems the voltage profile is not nearly as consistent as the existing batteries.
The second step was equipping our router with solar. So far so good. This setup has proven to run continuously, though only time will tell. The back story is that in order to stretch out the reporting units spatially, you have to support the radio signal strength with special units (routers) that bridge the gaps. While we can send our reporting units to sleep to conserve power, we can’t do that with the routers. Therefore, solar!
Today we added four new reporting units to the network. This includes one more red maple, to make five, and three new birches. Two more birch trees will be added in the days to come. This will round out the network to five red maples and five birches. While these units are reporting data, the actual dendrometer sensor has not yet been attached. What does this mean? Just that the units are up and running, but sending us useless data for now.
On The Technical Side
There continues to be a stability problem with the logging unit (the unit that the dendrometers send their data to that uploads to ecosensornetwork.com) and is responsible for the gap in data on the site. This seems to have been resolved at Lamont with the addition of an external battery. The same will be done at Black Rock.
Work still continues on power consumption, though, the 4,000 mAh batteries from Voltaic Systems have been replaced with 10,000 mAh rechargeable D-Cell batteries. This has prolonged the life of the units from 6 days to about 13.
All units reporting as expected. Replaced the standard Voltaic Systems 4,000 mAh battery in “The Super Stars” reporter with 3 D Cell batteries, hoping to lease double longevity of the unit. Initial voltage of the battery pack was 4.8v.
“The Homers” is now reporting. Before conducting signal tests, the main board and the ADC board were replaced. The Xbee and CPU were retained. This was done to eliminate soldering/construction problems. However, that seems to have been the problem. The unit is now reporting and data is available under public reports.
The Make: Nature workshop at this summer’s Black Rock Forest Summer Science Camp was a success! Twelve awesome kids got a chance to learn to how to solder and the basics of circuitry. They used those skills to construct and deploy their electronic, wireless point dendrometers on four red maples near the science center. Looking at the data collected with their devices, the kids got to compare their hypothesis of tree stem shrinkage and swelling from water use against actual dendrometer data. Be sure to head over to the data collection site to check out the charts!
On the Technical Side
There seems to be a bit of variability on battery longevity. The last charge at the Lamont installation lasted over 6 days. This would indicate a variation in current usage by the reporting unit, perhaps related to heat.
Next week we will be assembling and deploying four new dendrometers at the Black Rock Forest Consortium Summer Science Camp. A number of middle schoolers will be able to see what goes into constructing and installing the dendrometers and get a chance to answer some questions about how our trees change from day to day.
On the Technical Side
It seems that wet foliage and understory can contribute to signal loss when the signal is weak to begin with. At the research and development network at the Lamont Doherty site we experienced signal loss after rain. After repositioning the logging unit in a window we experienced much improved results. We also changed radio frequency settings to avoid interference from nearby wifi.
Battery life is at 5 days using a 4,000 mAh battery. In development is expanding the reporting period to improve battery life.
Greetings. This site is currently being set up but will provide the latest updates on the development of the dendrometer project. Feel free to sign up to the mailing list. This list will provide updates to the project.