Blecky developed a Wi-Fi positioning system to be used where GPS won’t reach:

SubPos is an indoor positioning system that can be used in various environments such as metro lines, shopping malls, carparks, art galleries or even conference centers; essentially anywhere GPS doesn’t penetrate. It could also be integrated into an array of IoT enabled devices, from access points to Wi-Fi enabled light-bulbs.

SubPos Nodes transmit encoded information in a standard Wi-Fi beacon frame which is then used for position trilateration:

The Nodes provide a pre-calibrated device that is easy to configure and can be dotted about with ease:

• USB power connector
• USB to UART
• USB firmware updates
• Frequency shifting
• Secure (generates raw beacon frames)

The hardware files and firmware is available on GitHub:

blecky has shared the board on OSH Park:

SubPos

The source code for a receiver module which works with the ESP module:

Tested on Arduino and the Teensy 3.2 as well as Energia and the Launchpad Tiva

Blecky is now working on an extended ranging system based on 802.15.4 for use with the SubPos Positioning System: