Singapore firm working on "indoor GPS"(在线收听

   SINGAPORE, Oct. 10 (Xinhua) -- A Singapore start-up firm has devised an innovative application to allow phone users to have access to their positioning information within buildings, where traditional global positioning system has often proved inaccurate, local daily Business Times reported on Monday.

  The firm YFind Positioning System feels that the application can help turn Singapore into the world's first location- intelligent city.
  Ting See Ho, co-founder of the firm, said the application works by first verifying the GPS coordinates to identify the building the user is in, and then collecting RSSI (received signal strength information) readings off WiFi access points within the building.
  The information is then sent by the phone to the central positioning server for comparison against records of the radio map of the building, which is calibrated earlier by the company.
  Ting said the RSSI readings continually fluctuates, making it difficult to estimate a position. This is where YFind Positioning System steps in with its patent-pending probabilistic algorithms to help accurately estimated the user's indoor positions.
  Once the phone application determines the location, then, it is able to map a course for a shop or other destination within the building where the user wants to go.
  "You can think of it as creating an 'indoor GPS' environment in the buildings where satellite signals cannot be read," Ting said.
  He said that more than ten organizations in Singapore have approached the company to discuss deployment and partnerships and that it has begun work on three proof-of-concepts.
  The company's immediate goal is to make Singapore the world's first location-intelligent city before going to other cities, he said.
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