Galaxy Nexus built-in barometer discussion: "2D GPS" and "3D GPS"

Google and Samsung collaborate in released last week by the new Galaxy Nexus, this phone carrying a lot of "new stuff", for example Barometer (Barometer). In the subsequent media comments and developers discussion, all think that mobile phones with built-in barometer is in order to predict the weather, help developers to make more accurate weather class App.

But Google engineer Dan Morrill in Google + described the role of barometer:

In fact Galaxy Nexus barometer and not outside had conjectured so mysterious. It is the most key role, is to let the GPS positioning faster and more accurate.

In theory, GPS is a four-dimensional system, it can get a 3d space coordinates and a time to coordinate. That's right, most wireless base station is through the GPS to gain time (in synchronous communication system is of vital importance to the). But a big weakness is GPS: precise positioning your geographic coordinates, the need for a couple of minutes.

This is why you of cellular phone specification table to write "AGPS" (assisted GPS) sake-mobile phone use base station information can be quickly locate, but not high accuracy, and is limited to the plane. I put the location called "2D GPS".

At this point, if plus barometer, you can obtain a rough altitude. So the positioning even faster.

From Dan Morrill give answer we can know, barometer also counted as part of the "auxiliary GPS", just put the auxiliary of the range from 2 D extended to 3 D.

But from the Massachusetts institute of technology (MIT) Luke Hutchison questioned, "judge with barometer height, is not the most simple and the most reliable method. Why not from the base station information gain height?"

Google's another engineer Casey Barker to answer the question:

From the reality of data to see, there are few ground stations will identify highly information. Most wireless equipment and WiFi hotspot, only identify plane coordinates.

You said to the barometer is accurate height of judgment. I can tell you, in this cell phone barometer, still have a temperature sensor, the temperature of capturing information can be used to correct height value. The algorithm will be enough.

But, the spread of thinking, developers can use barometer write more creative application? Even game? Of course is to look forward to!