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    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_d0e269218_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_d0e269275_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>