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Symbian3/PDK/Source/GUID-A5510456-A5EB-59EC-B146-74D58A118875.dita
changeset 1 25a17d01db0c
child 3 46218c8b8afa 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/PDK/Source/GUID-A5510456-A5EB-59EC-B146-74D58A118875.dita	Fri Jan 22 18:26:19 2010 +0000
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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-A5510456-A5EB-59EC-B146-74D58A118875" xml:lang="en"><title>LBS
+System Clock Synchronisation Overview</title><shortdesc>This topic describes how LBS synchronises the system clock with
+time data received as part of the GPS signal. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<section><title>Introduction</title> <p>The GPS signal contains accurate time
+data. LBS can use this data to synchronise the system clock with GPS. The
+system clock is synchronised with GPS at regular intervals if the difference
+between GPS time and the system clock time exceeds a threshold time difference. </p> </section>
+<section><title>Key concepts</title> <dl>
+<dlentry>
+<dt>System clock</dt>
+<dd><p>The mobile device clock that keeps system time. </p> </dd>
+</dlentry>
+<dlentry>
+<dt>Set clock plug-in DLL</dt>
+<dd><p>An optional licensee ECom plug-in DLL used by LBS to set the system
+clock. Symbian provides a default class that sets the system clock by calling <xref href="GUID-C197C9A7-EA05-3F24-9854-542E984C612D.dita#GUID-C197C9A7-EA05-3F24-9854-542E984C612D/GUID-145F52E6-2A29-3FF1-8AD1-7009BE0074D7"><apiname>User::SetUTCTime()</apiname></xref>. </p> <p>It
+is only necessary to implement a set clock plug-in DLL if a licensee requires
+to set the system clock by some means other than by calling <codeph>User::SetUTCTime()</codeph>. </p> <p>Whether
+LBS uses a plug-in DLL or the Symbian default class is configured through
+the <xref href="GUID-23BBC1D8-B3A0-5148-A4F1-22ECF3043E4E.dita">LBS administration
+service</xref>. </p> </dd>
+</dlentry>
+<dlentry>
+<dt>UTC</dt>
+<dd><p>Co-ordinated Universal Time. A worldwide time standard. UTC is derived
+from the GPS signal and is the time standard used to set the system clock. </p> </dd>
+</dlentry>
+</dl> </section>
+<section><title>API Summary</title> <p>There are two separate APIs involved
+with LBS system clock adjustment: </p> <ul>
+<li id="GUID-C8F1C9F9-E1D8-5F93-B6EC-6FDA8D81D5E8"><p>The LBS Set Clock Plug-in
+Interface </p> <p>Licensees can derive from the interface to create an implementation
+class. The class is packaged as an ECom plug-in DLL which is loaded at startup
+and used to set the system clock. </p> </li>
+<li id="GUID-ED0758AB-DC45-5EE7-97D3-FFAA9CB1CE3E"><p>Automatic clock synchronisation </p> </li>
+</ul> </section>
+<section><title>The LBS Set Clock Plug-in Interface</title> <p>LBS defines
+an interface class that is used to create a set clock plug-in DLL. </p> <p>The
+interface <xref href="GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5.dita"><apiname>CGPSSetClockBase</apiname></xref> is shown in figure 2. </p> <fig id="GUID-EEA7FD08-77F2-563F-BD94-DC74DC1A96DE">
+<title>              Figure 2. CGPSSetClockBase is the interface for LBS set
+clock plug-in              classes.            </title>
+<image href="GUID-9BA295BC-627C-5B82-B669-F4F7B55E3F82_d0e437178_href.png" placement="inline"/>
+</fig> <p>To create a set clock plug-in, licensees create a class that derives
+from <xref href="GUID-E5ED4ACA-5EC4-3AE2-862A-AC204DCA83B5.dita"><apiname>CGPSSetClockBase</apiname></xref> and package it as an ECom DLL. </p> <p>See <xref href="GUID-F0BDE1EC-5042-5328-9290-22BB2189F6B4.dita">How to implement a LBS set
+clock plug-in DLL </xref> for more information. </p> </section>
+<section><title> Automatic clock synchronisation</title> <p>LBS can perform
+automatic synchronisation of the system clock. LBS administration settings
+configure automatic clock synchronisation. The settings define the frequency
+of automatic clock synchronisation and by how much the system clock and UTC
+can differ before the clock is synchronised. </p> </section>
+<section><title>LBS system clock settings</title> <p><xref href="GUID-23BBC1D8-B3A0-5148-A4F1-22ECF3043E4E.dita">LBS
+administration</xref> describes how to configure LBS system clock synchronisation
+settings using either the LBS Administration API or a repository initialisation
+file. </p> </section>
+</conbody><related-links>
+<link href="GUID-F0BDE1EC-5042-5328-9290-22BB2189F6B4.dita"><linktext>How to Implement
+an LBS Set Clock Plug-in DLL</linktext></link>
+<link href="GUID-23BBC1D8-B3A0-5148-A4F1-22ECF3043E4E.dita"><linktext>LBS Administration</linktext>
+</link>
+</related-links></concept>
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FCL/sftools/depl/docscontent