This technology uses infrared light and ultrasound positioning technology. The technology works in a similar way to lightning in a thunderstorm by computing the time difference between the speed of light and the speed of sound. An infrared IWB is also available in a portable format. After moving the set-up to a new location, the system acquires connection to the computer with a simple re-calibration of the projected image — again using the electronic pen. The device or bar scans a bracketed area (usually 3m by 1. 5m, giving a whiteboard that is 110" wide). Typically, multiple brackets can be added, providing for users at different sites to share the same virtual whiteboard. A portable IR pen-based whiteboard works on a variety of surfaces — an existing whiteboard, a flat wall, even a chalkboard with dry-erase paint, transforms those surface into an interactive whiteboard. No battery is required for USB signal receiver and the unit can be mounted to the ceiling if a permanent solution is required. Made of a tiny and lightweight material, the PIWB is easy to transport.