Tuesday, February 10, 2009


I've been out in Chicago working for 2 weeks at the Borevitz Lab. I'm working on mesh network based environmental sensors for the team to use in quantifying microclimate data, its effects on the ecosytem, and specifically the flora and fauna. Currently they use the Hobo weather station which they use at several locations including the University of Chicago and the Indiana Dunes park nearby. Some nice images of the last month's data is displayed on the weather stations page. This is a big first step down the path of beginning to get real industrial quality data about our environment and ecosystem to help guide our decisions for the future.

There are of course some limitations. These stations are EXPENSIVE! just the basic data logger is about $500 and of course it gives you no ability to do anything wireless. That's a big one. You can put a sensor nearb
y without using a cable, which can break, and degrade any analog signals as well. Of course this is why we are investigating mesh netoworking to take this solution to the next level. Currently I'm using a proposed "Air Station" to drive early prototype development. One of the sensors I mention on that page is the Chipcap which you can get for about $7 and will survie -40 to 85 C, and all it needs is some nice packaging and a connector to equal the sensor Hobo sells for $170! (Shown is the Air Station in Development)

Also with the mesh networking built in, it will be possible to build cheaper micro sensors that will not require their own backhaul. Currently the hobo stations also require that you either go download the data periodically (not real time), use Wifi (not available many places), or pay for an expensive cell contract (expensive). We propose to alleviate this need by using the mesh network for localized connectivity, while accepting that a more expensive backhual 
communciations methodology will be necessary. Some of these sensors (which don't require a timing based digital bus) can be implemented as dumb terminals with Zigbee sending out packets for either ADC or low speed DIO pins. This means Zigbee Card ($20) + Solar Panel & Battery ($20) + Sensor & Packaging cost is now our baseline. There's even tiny AT91 based boards available for $20 which could enable us to have a pretty cheap smart solution as well.

We also recently went out to the Indiana Dunes and I will post some pictures of our trek shortly.