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A comment on IPhone 4S has GLONASS in addition to GPS. Parent comment

Re:IPhone 4S has GLONASS in addition to GPS by mikepurvis on Wednesday October 19, 2011 @08:08AM (#3129734)
It's called rtk correction: http://en.wikipedia.org/wiki/Real_Time_Kinematic

There's an opensource rtklib which supports a handful of inexpensive receivers: http://gpspp.sakura.ne.jp/rtklib/rtklib.htm

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Re:IPhone 4S has GLONASS in addition to GPS by modeless on Wednesday October 19, 2011 @12:16PM (#3130790)
Why don't cell towers do this?
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Re:IPhone 4S has GLONASS in addition to GPS by fleitz on Wednesday October 19, 2011 @01:59PM (#3131261)
Cell towers kind of do by providing an accurate time and other features in AGPS.
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Re:IPhone 4S has GLONASS in addition to GPS by modeless on Wednesday October 19, 2011 @04:04PM (#3131809)
Not really. AGPS improves the time it takes to lock on to the GPS signal, but it doesn't improve accuracy.
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Re:IPhone 4S has GLONASS in addition to GPS by nobody314159 on Wednesday October 19, 2011 @05:05PM (#3132089)
You need a receiver in the phone that can phase track, which costs 50x as much as the simple GPS chip they fit.

You also need either a lot of storage locally or a fast data link between the base station and the rover - phones actually have both of these but they cost money

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Re:IPhone 4S has GLONASS in addition to GPS by jrockway on Wednesday October 19, 2011 @07:15PM (#3132572)
You need a receiver in the phone that can phase track, which costs 50x as much as the simple GPS chip they fit.

So, $0.50 instead of $0.01? :)

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Re:IPhone 4S has GLONASS in addition to GPS by nobody314159 on Thursday October 20, 2011 @02:18PM (#3136095)
I think Phase tracking GPS chipsets are still pricey - outside surveying applicatiosn there isn't much demand.
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