So where do those GPS maps come from?

So while the Global Positioning System (GPS) definately was born of military applications; GPS applications in the civilian sector has expanded beyond anyones wildest imagination. Heck, I normally have a GPS navigation system when I travel and have consistently able to cut several hours off driving time when making my way around an unfamilier city. In most cases I'm no longer afraid to cut it a bit close on appointments since I'm confident I won't be spending hours lost.

The folks at TeleAtlas have had a long list of milestones on their way to becoming one of the most popular map sources for consumer GPS & GIS products. Through the combination of using inertial navigation in combination with GPS data, TeleAtlas vans have been crisscrossing the world to create maps accurate within 5 meters in some key urban areas.

Interestingly enough this accuracy is apparently being used for some E911 (enhanced 911 emergency services) in parts of the US.

Another big change in the world of GPS is how long older GPS's take to find enough sattelites to get a position fix and that while radio signals penetrate buildings just fine (just like AM or FM radio) the weakend signal isn't always enough to get a position lock. Sirf Technology tackled the weak signal problem and has become one of the most popular GPS engines on the market today. Last year I got confused stares when I asked around about SIRF based GPS systems, but this year all the major GPS vendors has SIRF based systems.

On a geeky note, I'm hoping to get my hands on a Sirf development kit to see if I can get the open source NTP server software running with the new Sirf GPS engine so that I could possible provide super accurate NTP sync indoors.

Brian Chee is a Senior Contributing Editor with InfoWorld Magazine and is a researcher with the University of Hawaii's School of Ocean and Earth Science and Technology (SOEST).

Posted by Brian Chee on January 12, 2007 04:16 PM

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COMMENTS

What about GPS indoor capability?

GPS fails because it does not work where people are: indoors and in cities. GPS is great, but not for many applications that require higher accuracy, precision, coverage, and reliability. Conventional GPS receivers do not work inside buildings due to the absence of line of sight to satellites, while cellular positioning methods generally fail to provide a satisfactory degree of accuracy...

http://indoorLBS.com

Posted by: IndoorLBS at January 17, 2007 02:27 PM

Sorry, the comment about GPS indoors was more along the line of not needing line of sight to get accurate clock sync from the GPS signals while indoors. At issue here is just getting enough of a signal to get clock, not position. So while a room at the interior of the building won't work, being able to suction cup a GPS antenna to a window (even if it can only see a sliver of sky) should give you a view of a sattelite as it goes by...two is pretty much all you MUST have to get a relatively accurate clock. (this way you can calculate angle and thusly delay) I would love to be able to use cellular sources (which in the case of GSM are typically GPS sync'd clocks) but cellular modems aren't as cheap as the Garmin OEM "puck" which I got for under $60. (cost is calculated with the recurring GSM charges)

So yeah, point taken about position, but I keep hoping that I can get accurate clock from such an arrangement. Especially as more and larger databases keep appearing as folks do distributed directory based authentication systems. (see IDM Shootout last year)

Posted by: Brian Chee at January 17, 2007 03:28 PM

So where do those GPS maps come from?

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