Dan Morrill: Barometer on Galaxy Nexus Will Help With GPS

Written by: Chris Kerrigan on October 20, 2011.

When Samsung revealed that the Galaxy Nexus would include a Barometer, it opened the door for many to question the exact reason behind it. Is it to predict weather? Is it to help determine altitude? Well, Dan Morrill, an Android engineer has clarified the exact reason a barometer was included with the Galaxy Nexus and points to the fact that it will significantly improve GPS performance. Here’s what Dan said:

I’ve seen a lot of hay made about the barometer in Galaxy Nexus. Here’s the skinny; it’s not really as dramatic or weird as people think.

The primary purpose of the barometer is (at least, I’ve been told) to make GPS lockons faster. Locking on to a GPS involves numerically solving a 4-dimensional set of linear equations — 3 dimensions in space, and time. (Yes, you get accurate time for free if you lock on to GPS.) Because of the way GPS works, this can take a few minutes.

This goes much faster if you already have an estimate of your location. This is why “aGPS” (assisted GPS) services are so popular: by starting with a rough city-level coordinate fix through something like cell-tower network location, you can reduce the amount of math you have to do to lock on. This is where the barometer comes in.

The 3 dimensions in space are latitude, longitude… and altitude. The barometer gives you a reasonable first-cut estimate for altitude. This gives you a bit of a leg up on one of the dimensions — especially combined with “2D” aGPS — which can help speed up lock-on in general.

Now of course, the barometer can also be used for things like, well, determining atmospheric pressure (although I’m not sure it’s really weather grade.) But the main reason it’s in your phone is to help with GPS.

Also, it’s worth noting that Xoom has a barometer too, so it’s not a new thing.

Touché, Dan. Digging through that statement, it might be safe to assume that the Galaxy Nexus should have far better GPS performance and GPS lock times than most other Android devices, but we’ll have to wait until we get our grubby little hands on one before we can draw conclusions.

via Google+