uRADMonitor is a network connected monitoring station, focused on continuous Environmental Radiation Surveillance.
This capability is delivered by a digital dosimeter constructed around the highly sensitive Geiger Muller tube SBM-19. Additional sensors gather real time data on temperature , humidity and sky luminosity.
I made a presentation Video (please see it in HD and full screen):http://www.youtube.com/watch?v=O4cqDWPrW50
Everything is packed in a homemade PVC box and placed outside my home, in Timisoara, Romania. The box is relatively small, and it takes only two connectors: power (6V) and an Ethernet cable for internet connection. From that point, everything is automated, it gets an IP via DHCP, and then starts sending data online every single minute.
On the other end, there's a PHP script, that takes the data, stores it in a mySQL database. From this point, we have everything in place for showing charts or analyzing Radiation variations in time, or in relation to other parameters monitored. This is doing research the fun way!
The image above is a real time data chart!
. It shows the radiation data collected over the last 5 days, integrated at a 2hours time interval, with timestamps computed for GMT+3 (Europe/Romania). Try refreshing the page after several minutes to see the numbers change? How is this possible? Well I made it so:
By accessing the image, you are actually accessing a PHP script, that interrogates the SQL database for the radiation data. Then the data with a 1minute resolution is integrated (averaged) for a 2hours interval. A graph is generated on the fly, and the image returned, like you would have accessed a normal PNG file.
Of course, there's also a smart caching mechanism, to prevent my server getting killed by multiple requests: each time you ask for a graph, based on several parameters (interval, integration, gmt, data type, etc), the PHP script looks if the image has not been generated already, and if there is an image matching these parameters, it checks that it is not older than 2 minutes.
There's much to add here. I will probably structure it in several posts. This project contains knowledge gathered for more than one year. Everybody makes geiger counters nowadays, but crucial issues are treated superficially: dead time, energy response compensation, tube's life, driver circuits / inverters, and so on. I'll try to bring my part of contribution here.
Construction details are also available on my blog: http://www.pocketmagic.net/?p=2457
(it is a very long article)
Or more details on uRadMonitor's page: http://uradmonitor.pocketmagic.net/