Light-based Hospital GPS

Talking Lights, a Boston, MA startup, is working on a system to assist people with cognitive problems to navigate. Developed to be used inside nursing homes and hospitals, the system uses a network of modified fluorescent light fixtures with unique flicker signatures, which are then used to navigate someone who has a specialized hand held computer. The idea is to assist patients moving around the hospital when they receive a variety of tests and procedures, in case they have trouble remembering how to get from one place to another.

The Talking Lights System is an optically-based, multiple-use, context aware local area wireless system for data transmission that makes it possible to achieve GPS-like position identification and guidance indoors, where GPS doesn’t operate accurately.
The Talking Lights communications link is created by modulating the light from an ordinary light fixture to encode information. The light continues to perform its original function of providing bright illumination without visible flicker while simultaneously establishing an information link for context-aware data transmission. The system has three parts:

a modulated light fixture that transmits a locator signal.

a portable receiver to acquire the signal.

software to process the signal from the light and furnish data to the receiver.

As it approaches the modulated light fixture, the receiver decodes and processes data from the light and transforms it into information that can be presented in analog or digital form. The Talking Lights System can be used to form a hybrid network that combines the advantages of optical location-finding with broadband WiFi duplex data transfer.
The Talking Lights network enables the receiver to determine its location or travel path, while the Wi-Fi network communicates rich information that is tied to a specific location.

Technology page: Talking Lights®…
More at the MIT Technology Review…