And a movie of it in operation is here:
http://www.youtube.com/watch?v=9m0oSjSQkrE
Installation is very easy - simply plug the device in. The onboard
GPS will determine it's location and assign the correct inbound and
outbound stops for the display. If the device is deep inside and a
GPS fix is not available the nearest cell tower location will be used
to assign appropriate bus stops. To confirm or change stop numbers
simply call 617-208-4063 and enter the device serial number and PIN if
assigned. The prototype device serial number is 9876
A recycled cell phone contacts my server which provides the prediction
time for the selected stop.
Display of bus arrival time with a familiar clock face has numerous
advantages over digital displays. Time to arrival is easily
understood and can be read to the minute, yet a clock-hand indicator
conveys an appropriate level of precision. Unlike digital signs which
increase in cost with the square of the size, a clock face scales from
room size to stadium readable size with relatively little increase in
cost. The clock face is a format that advertising buyers are already
familiar with and provides ample space for advertising.
http://www.adcomarketing.com/Category/Wall-Clocks-Custom-Promotional.html
The technology that makes this kind of connected sign possible for a
very low cost is the availability of low-cost recycled cell phones
commercially available from:
http://recellular.com
http://www.pacebutler.com/inventory.cfm
Cell phones that would work for this application are available in
quantities of 1000's for less than $10 and data plans for these phones
cost less than $5 per month.
You can see in this photo that a recycled cell provides the GPS and
network connection.
http://www.flickr.com/photos/gadgeteer/4445619377/
The hands are driven by commodity hobby servos controlled by a circuit
connected to the phone's serial port. The total Bill of materials
cost for this device is below $30