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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-92AD13DF-216A-4B5A-9C6D-5FA50BB0D692" xml:lang="en"><title>Sensor

Data Compensator Overview</title><shortdesc>The Sensor Data Compensator provides APIs to correct sensor data,

based on device or display orientation. That is, using the APIs, the coordinate

system can be adjusted appropriately to get correct sensor axis data in relation

to the Symbian device user's current display orientation.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-173CC4BB-4C2D-43B0-9ADD-85C716B9297B"><title>Description</title> 

     <p>The sensor channel APIs retrieve coordinate information and angle

data from different sensors when a display or device orientation change is

detected. The data is bound to the device form factor and hardware configuration

using device based coordinate system. Using the data, the sensor data compensator

APIs can adjust the coordinate system to match the changed system characteristics.

This procedure is called sensor data compensation. </p><p>For example, if

a display orientation change (as illustrated in the following figure) is detected,

the accelerometer sensor provides axis data using the device base coordinate

system. To convert the axis data to match the current display orientation,

sensor data compensator APIs can be used. The data compensator APIs enable

you to adjust the coordinate system to match the changed system characteristics.</p><fig id="GUID-CB810DA3-6532-47DF-878E-A0D8A07ACC7C">

<title>Example to illustrate adjustment of the coordinate system due to device

orientation change</title>

<image href="GUID-24B8686D-727A-47A8-B01D-1BA1FBC8F771_d0e114448_href.png" placement="inline"/>

</fig><p>To convert the sensor data to the compensated values, the adjustment

values (for example, interchanged x-axis with y-axis) for each device state

that the compensation is applied to, must be configured and taken as an input

for calculations.</p><fig id="GUID-15844543-6586-43AE-87C8-B90A4D24404D">

<title>Correcting the coordinate system of a Symbian device</title>

<desc>The figure depicts the correction of coordinate system in the Symbian

device</desc>

<image href="GUID-BF822A89-F932-400F-82FC-FB998B768EBF_d0e114460_href.png" placement="inline"/>

</fig><p>The following example explains how the sensor data compensation works,

by illustrating the behavior of maps application of the Symbian device when

the keyboard is in opened and closed state. </p><table id="GUID-6CF1E7CE-0076-415F-BF6A-E92034B6F6D4">

<tgroup cols="3"><colspec colname="col1"/><colspec colname="col2"/><colspec colname="col3"/>

<thead>

<row>

<entry valign="top">Symbian device position</entry>

<entry valign="top">Symbian device movement</entry>

<entry valign="top">Application behavior</entry>

</row>

</thead>

<tbody>

<row>

<entry>The keyboard is closed and the display is upward and parallel with

the table surface</entry>

<entry>The Symbian device spins around the z-axis</entry>

<entry>The compass needle points to the north and the map does not move on

the screen.</entry>

</row>

<row>

<entry>The keyboard is opened and the display is upward and parallel with

the table surface</entry>

<entry>The Symbian device spins around the z-axis</entry>

<entry>The compass needle points to the north and the map is always in the

north-south direction on the screen.</entry>

</row>

</tbody>

</tgroup>

</table> </section>

<section id="GUID-983C07BB-4B1A-4030-A533-22728BDCF281"><title>APIs</title><table id="GUID-B0112D3A-0CCB-47FF-BF2C-6DC4EE1217A7">

<tgroup cols="2"><colspec colname="col1"/><colspec colname="col2"/>

<thead>

<row>

<entry>API</entry>

<entry>Description</entry>

</row>

</thead>

<tbody>

<row>

<entry>CSensorDataCompensator</entry>

<entry>The sensor data compensator class provides functions to

compensate sensor data.</entry>

</row>

</tbody>

</tgroup>

</table></section>

<section id="GUID-E046AE53-A268-4085-8BF4-293873115857"><title>Typical Uses</title><ul>

<li><p><xref href="GUID-64AC6F53-A9A5-46FD-BCC6-4A9BD8D4DB5C.dita">Compensating

Sensor Data</xref></p></li>

</ul></section>

</conbody></concept>