Edition: U.S. / Global

Business Day

How Google Collected Data From Wi-Fi Networks

While taking pictures for its Street View project, Google also recorded Internet traffic from open Wi-Fi networks in homes and businesses. To capture the images and the data, Google used cars equipped with roof-mounted cameras and computer hardware. Related Article »









By recording the location and ID of

wireless routers, Google can

triangulate a smartphone user’s

location faster and with less power

than using satellites.

1 The Google

car’s on-board computer

listens for wireless routers, recording

each router’s unique hardware ID as

well as its approximate GPS


4 In the

one-fifth of a second

that the computer is connected

to a network in each cycle, the

amount of data collected could

be as much as 250 kilobytes,

equal to roughly 25 e-mails, or



It is also possible that a car may

connect with a network multiple

times, if, for example, it is

stopped at a red light.

2 If a Wi-Fi

network is not password-

protected, the car’s computer also

saves any data transmitted across

the network.


That traffic can include e-mails and

information from password-

protected sites, which are not

necessarily encrypted.


If the network is password-protected,

the computer does not save any of

the network’s traffic.


3 The car’s

computer maintains a

connection with a given

network for only about

one-fifth of a second,

because the software

cycles through 11 Wi-Fi

channels every 2.2

seconds. A Wi-Fi router

generally broadcasts on a

single channel.