(Note that due to technnical limitations, the webcam and GPS system cannot be in operation at the same time. This may change soon .. just need to pick up a USB hub for the laptop and write a local GPS client)
The object tracking system employs the following hardware:
The object tracking system uses the following software:
The GPS receiver is directly connected to the Sage wireless IP modem via serial. The Sage has a built-in TCP/IP stack which can accept and initiate TCP or UDP sessions. Using this ability, I am able to access the serial port of the modem directly and poll GPS information via NMEA back to the server. This happens at about once a second, and the system parses the NMEA stream for latitude, longitude, ground speed, altitude, and signal quality.
From this point, a PHP script reads this data and generates a link to the TIGER Map Server. This is the mapping image you see, and is free for anyone to use.
How does the mobile webcam work?
Similar to the GPS configuration, the CDPD modem is connected to a small computer (laptop, embedded system, etc) and is currently contained in a backpack. A Logitech Quickcam is connected to the laptop, which uploads a picture every n seconds (It works great from 7-30 seconds). Very simple, but very cool and effective.
What is CDPD?
CDPD is an obscure data packet radio service provided by AT&T Wireless (and other providers with AMPS equipment). This system makes use of unused cellular channels for raw data rates of 19.2kbps. After encryption and framing overhead, the connection speed is around 14.4kbps.
AT&T's CDPD service plan provides internet access, a static IP address, and either a metered or unlimited service plan. Coverage is available in most metro areas, and the footprint isn't that far off from your PCS counterparts such as Sprint PCS, Voicestream, etc.
CDPD equipment can be used on laptops, palm pilots, and PDA's, etc.
For more information on CDPD service, visit AT&T Wireless IP.