Path: csiph.com!x330-a1.tempe.blueboxinc.net!aioe.org!news.glorb.com!news2.glorb.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail NNTP-Posting-Date: Tue, 29 Mar 2011 10:52:21 -0500 Date: Tue, 29 Mar 2011 08:52:13 -0700 From: Patricia Shanahan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 Newsgroups: comp.lang.java.programmer Subject: Re: GPS Requires Network?? References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Message-ID: Lines: 39 X-Usenet-Provider: http://www.giganews.com NNTP-Posting-Host: 75.8.126.96 X-Trace: sv3-oLLfFvf0NlAI2vUIGJlgpgdEOZrGVKCxv5ZjOyyzkbu5KKbVdBJXITOb/EN3DAH/qZrv49hl11xFLfC!cmSwFknUtx3qfn0yD0tsn4BrpvZPogYgab4YlP3WQm0AfrkOGl07Xfl11aXPNSDLdFhQ8e7mBD0I!JEgN98d3HXRIaejdfA771jY1Fjg6+ASs13+oJFL6cHI= X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 2990 Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:2548 On 3/29/2011 3:42 AM, Patricia Shanahan wrote: > On 3/28/2011 3:26 PM, Lawrence D'Oliveiro wrote: >> In message, Bent C Dalager wrote: >> >>> On 2011-03-28, Lawrence D'Oliveiro >>> wrote: >>> >>>> Why would GPS require a network connection? >>> >>> If LocationProvider provides both fine grain and coarse grain >>> localisation services, then it uses GPS for the fine grain >>> localisation which obviously requires access to the satellite >>> receiver; and it reads nearby WiFi SSIDs to calculate coarse grain >>> localisation which requires access to the WiFi radio. >> >> There is a separate LocationProvider called “network”, that says it >> requires >> both a cellular network (requiresCell()) and data network >> (requiresNetwork()). That provides lower accuracy than GPS, so there’s no >> reason for the GPS provider to do the coarse-grained stuff as well. >> > > Maybe it is using the network LocationProvider as a back-up for > situations, such as inside many buildings, in which GPS does not work > but cell and WiFi are available. Incidentally, this is a testable hypothesis. The test would consist of taking the device into a building or parking structure, with a few layers of reinforced concrete between the device and the sky, and asking the GPS provider for a location. If the hypothesis is correct there will be cases in which it reports insufficient satellites for a GPS fix, but gives a location. If the hypothesis is incorrect, it will fail to report a location if it has insufficient GPS satellites, even if there is cell phone and WiFi coverage. Patricia