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Challenge 1 :
Audio Graffiti
Rationale and architecture We decided upon a solution where audio graffiti tags are placed in the environment. Users carry small devices, shaped as pocket-size spray cans (equivalently, an active name badge would also do the trick). The graffiti tags and the spray cans are wireless and battery-powered. Tags sense close proximity of a spray can via infrared beacons sent by the can. When proximity is detected, the graffiti tag notifies the can, and the can beeps or flashes an LED (depending on the user's preference). If the user chooses, they may listen to any audio graffiti associated with the tag, and/or add their own audio graffiti to which others can listen. Scalability Graffiti tags can have a number of form factors and storage capacities. Small, post-it-note shaped tags might store a minute or two of audio, while larger tags might store several hours. Larger tags could be used in more public areas such as meeting rooms, whereas smaller tags could be associated with corridors, offices, and even particular objects. If mass-produced, tags can be manufactured such that they are inexpensive; users can then deploy tags for new areas or objects without incurring significant cost. As proof-of-concept, a prototype graffiti tag and spray can were produced. GraffitiTag Implementation
The graffiti tag consists of a Smart-Its, an infrared receiver, a small speaker, and a £5 off-the-shelf voice recorder module available from Quasar Electronics: http://www.quasarelectronics.com/sound_recorders.htm
On the graffiti tag, the Smart-Its performs the following function - control of voice recorder module record and playback functions - detection of incoming IR spray can beacons---IR receiver circuit is connected to Smart-Its analogue input pin; see below for schematic - radio communication with spray cans (necessary to advertise proximity of the can and tag) You can download the GraffitiTag software here. SprayCan Implementation: Again based around a Smart-Its, the spray can contains an infrared emitter, two buttons, a buzzer, and an LED. The buttons are red and green, and control the record and playback functions, respectively. The buzzer and LED are used to inform the user when a graffiti tag is in close proximity. Using the radio link, the Smart-Its is informed if a graffiti tag is in close proximity, and can remotely initiate recording and playback of that tag if the user presses the red or green button. You can download the SprayCan software here.
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