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Over the Air 2013

It's hard to think of a better place to have a hacking festival than Bletchley Park; home of Colossus, birthplace of the computer, location of the history of computing, with a grand mansion and close enough that we didn't need to get out of bed too early.

Over the Air is a weekend of talks, workshops and hacking where anyone with an interest in mobile tech can get together and find out about new developments, trends and techniques. Oh and it's a sleep over. In a mansion.

Bletchley Park Mansion


This year we joined forces with Paul @paul_tanner from Virtual Techno with whom we've been working on an internet of things project. He'd been chatting to some cyclist friends of his who had the idea of mounting air quality monitors on their bikes to track areas of pollution.

Since we like bikes, the environment and fiddling around with tech then this seemed like a good opportunity to see what we could do.

We used an Arduino with an AQE Shield together with a Bluetooth module. The AQE shield measures concentrations of CO and NO2 which are sent periodically to the rider's phone via Bluetooth. The phone then used its GPS to geotag the measurements and upload the data to a cloud server. The app can then pull down a real time heatmap showing the pollution levels.

The idea of the cloud based data store is that multiple bike inputs could be used together with data from permament air quality stations to create a real time pollution map. Citizen science in action.

The sensor was powered with a couple of AA bateries and carefully packaged into an old cardboard box which fitted into the bike's bottle cage.

The app running on a Nexus 4The Android app on the phone that handled the bluetooth connection, the geo-location, data transmission etc was built using Phonegap including the BluetoothSerial plugin. We used Bootstrap for layout and the map used Open Streetmap (of course) using Leaflet and the rather handy Leaflet Heatmap overlay. On the server side we built a very rough and ready API using PHP and mySQL.

Now obviously this was just a hack and there are clearly problems to be overcome if this was to be put in practice as a real-life solution. In particular the AQE sensors are not well calibrated, so whilst we were able to show that cycling around the Bletchley ring road was much smellier than the park (even after a hundred geeks had been camping there overnight) we couldn't give reliable values for concentrations of the gases we measured. We'd certainly need to look into how the data was handled as well and perhaps do some nicer packaging than our cardboard box.

Anyway - as a proof of concept we were pretty pleased to get something that worked and produced real data even if it may not have been particularly accurate. We were also very pleased that we won a prize - Best Science Hack. Airsome!

Sep 30, 2013