Symbian3/SDK/Source/GUID-BA49FDC0-808B-5E05-81AC-98637214F304.dita
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     1 <?xml version="1.0" encoding="utf-8"?>
       
     2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
       
     3 <!-- This component and the accompanying materials are made available under the terms of the License 
       
     4 "Eclipse Public License v1.0" which accompanies this distribution, 
       
     5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
       
     6 <!-- Initial Contributors:
       
     7     Nokia Corporation - initial contribution.
       
     8 Contributors: 
       
     9 -->
       
    10 <!DOCTYPE concept
       
    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
       
    12 <concept id="GUID-BA49FDC0-808B-5E05-81AC-98637214F304" xml:lang="en"><title>LBS
       
    13 Quick Start</title><shortdesc>Location Based Services (LBS) provides location information for
       
    14 installed applications and for remote services via a network. Location information
       
    15 can be used for location stamping artefacts such as photographs and memos,
       
    16 finding nearby services and facilities, navigation, and the ability for remote
       
    17 parties to discover the user's whereabouts. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
       
    18 <p>Location-based services (LBS) use coordinates from the World Geodetic System
       
    19 (WGS 84), which is also used as a reference system by the Global Positioning
       
    20 System (GPS). </p>
       
    21 <p>The coordinates are based on values for latitude, longitude, and altitude
       
    22 (elevation above sea level). </p>
       
    23 <p>The North Pole is 90 degrees North (+90 degrees) and the South Pole is
       
    24 90 degrees South (-90 degrees). The Equator is defined as 0 degrees; locations
       
    25 above it have positive latitudes (0 to +90 degrees); those below (0 to -90
       
    26 degrees) negative ones.</p>
       
    27 <p>There are two definitions of North Pole; Magnetic North Pole and True (Geographical)
       
    28 North Pole. Any application with a compass must check how the API defines
       
    29 North Pole.</p>
       
    30 <p>The Magnetic North Pole is the point to which compasses point. The True
       
    31 North Pole defines latitude as +90 degrees. </p>
       
    32 <p>Meridians are constant longitudinal (north-south) values. The Prime (Greenwich)
       
    33 Meridian’s value is 0 degrees. WGS84, which LBS use, defines its zero meridian
       
    34 some 100 meters east of the Prime one. Locations east of the Prime Meridian
       
    35 have positive longitudinal values (0 to +180 degrees), those west (0 to -180
       
    36 degrees) have negative ones. </p>
       
    37 <p>As seen in the figure below, latitude lines are smaller near the poles.
       
    38 At the equator, one degree of longitude is roughly 111.3 km, whereas at 60
       
    39 degrees of latitude one degree of longitude is only 55.8 km, which is more
       
    40 difficult to see.</p>
       
    41 <fig id="GUID-D98458F6-8EBD-43B9-9C3C-5204BD837D2D">
       
    42 <image href="GUID-0C01305E-9E73-4E44-BD13-361C93CC5E79_d0e240538_href.png" placement="inline"/>
       
    43 </fig>
       
    44 <section id="GUID-D4201DF5-26DD-5E46-B228-A3CAA467C7C6"><title>Getting started
       
    45 with LBS</title> <p>This section provides links to the most important documentation.</p> <p><b>For
       
    46 application developers</b> </p> <p>The <xref href="GUID-D0318BB6-0B9F-5A1C-AB0B-61BA22D28661.dita">Location
       
    47 Acquisition API</xref> is the interface that programmers use to create location-aware
       
    48 applications. The API gives developers the ability to get location fixes and
       
    49 to obtain information about the positioning technologies available to the
       
    50 mobile device. </p>      </section>
       
    51 
       
    52 <section id="GUID-CA5D2674-B469-44D8-9255-1F35CA7B8D41"><title>Technologies</title> <p>The
       
    53 main technologies enabled on the Symbian platform by the LBS subsystem are
       
    54 as follows: </p> <ul>
       
    55 <li id="GUID-62F84865-11D4-50BA-A139-7EEA7232BC8F"><p>Global Positioning System
       
    56 (GPS) </p> <p>The GPS system provides accurate, worldwide positioning. The
       
    57 main disadvantage of GPS is the long time required to obtain a position fix
       
    58 when the GPS hardware is first powered. LBS supports Assisted GPS (A-GPS)
       
    59 to reduce the time required to get a position fix. </p> </li>
       
    60 <li id="GUID-64669486-6B59-5AE4-A337-E9E50C3C3F1E"><p>Network based positioning </p> <p>Network
       
    61 based positioning is typically less accurate than GPS, but often provides
       
    62 a faster fix of adequate accuracy for some applications. </p> </li>
       
    63 <li id="GUID-05A9FF0E-A974-5CD7-A854-784CB23AA2A4"><p>Secure User Plane Location
       
    64 (SUPL) v1.0 </p> <p>SUPL defines an architecture for supporting Location Based
       
    65 Services using IP bearers to connect handsets and network hosts. The Symbian
       
    66 LBS subsystem contains a SUPL Protocol Module to support SUPL. </p> </li>
       
    67 </ul><fig id="GUID-52D81395-87C4-4706-97E5-84336EA53C69">
       
    68 <image href="GUID-0CCCF088-E636-4C12-AA5E-3E2CB04424AD_d0e240595_href.png" placement="inline"/>
       
    69 </fig><p>The above figure illustrates how the location information can be
       
    70 provided to the device. Access to these location methods is provided through
       
    71 the positioning modules.</p> </section>
       
    72 </conbody></concept>