AGPS in IDEN Phone’s for Motorola

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This article explains in a relatively brief way how the AGPS in IDEN cellular’s for Motorola operate; it is necessary to explain some concepts in order to use the libraries for Position, basic packages, and one example of how to use this technology.

API from Location
Various IDEN telephone models allow users to attain information from the GPS position such as, latitude, longitude, velocity, etc. This characteristic is seen as an integrated application on telephones with ergonomic standards and as API or interfaz J2ME that developers can use to create applications for customized tracking assistance (AGPS).

Precision
The phone is designed to receive fixed tracking within a level precision in a determined geographical from the network provider. Using the API J2ME in position the developers can recover a fix: however, the quality/value of the tracking is not guaranteed within that precision level. The API provides certain methods for determining a fix regardless of how precise it is.

Motorola strives to find the highest precision possible; however there isn’t any GPS system that can provide perfect precision in all circumstances. The precision of the GPS can be affected by the potential multitude of error factors, including GPS satellite signal conditions and the availability of packet data. The precision of the position is not guaranteed nor is it implicit.

Assisted Information
AGPS uses information from cellular assistance to recover a fixed tracking. The API from a position provides the developers with a method to determine what information from assisted cellular is used for fixed data.

Packets J2ME PARA Tracking

Basics
- import javax.microedition.io.*;
- import java.io.*;
- import javax.microedition.midlet.*;
- import javax.microedition.lcdui.*;
- import java.lang.System;
- import java.util.*;

Tracking AGPS
- import com.motorola.iden.position.*;

This API provides the following tracking functions for required applications for Java to access the GPS tracking information:
• Latitude
• Longitude
• Altitude
• Time Stamp
• Travel Direction
• Speed
• Altitude Uncertainty
• Speed Uncertainty

The Class “PositionConnection”
This interface supports the creation of a GPS receptor connection (Driver). The GPS position can be received and the state can be obtained after the creation of a connection. There is only a connection allowed one at a time. This API should be called from the separate thread than that of the principal application thread.

To obtain a PositionConnection, the Midlet should be used as a generic Conector class. For example:

com.motorola.iden.PositionConnection sc = (com.motorola.iden.PositionConnection)Connector.open(String name);

The String type can be one of the following:
• name = “mposition:delay=no”
• name = ”mposition:delay=low”
• name = ”mposition:delay=high”

Delay Types in Tracking

- Delay=no, Provides the latitude and longitude of the Cel of the application immediately. This request uses a GPS chip, and if the cellular is out of range of the network, the data of latitude and longitude will be 0.

- Delay=low, Provides a response of the application in a few seconds. The aid information is recovered only if it did not exist before, or if the aid information had expired according to the MADA (Maximum Assist Data Age). This option is designed to provide all the attributes of the position assistance in the server LES (Location Enhanced Service). In order to provide this information the handset needs the Service Packet Data. If the request is made outside of the network range then the API will not obtain information from the LES.

- Delay=high, Provides a response to the application where the delay is much longer than the previous confirguration. The configuration works on a fixed autonomous or assisted one for the application. The cellular is only information is assisted only when it is available or valid, other than that the fixed location will proceed autonomously.

Only a petition of getPostiion() can be made or if it is instant. If the application has multiple requests without reaching a desired answer to the previous petition, or if it has a zero value, returned, or if it is an exception to being launched.

Practical Example

It is looking for an example, through the developed application, shall obtain the latitude and longitude through the API location AGPS in accordance to a selected precisión”. The following will be shown with this application:

- A selection screen with the precise location (Item ChoiceGroup)
- The same screen, button to launch the locate request
- Another screen to see the results obtained with Latitude and Longitude(StringItem)
- The same screen a button to update the positions on the same screens.

Tools Used

- Netbeans IDE 6.1 - http://netbeans.org/downloads/index.html
- Motorola IDEN SDK - http://developer.motorola.com/docstools/sdks/

To create the screens rapidly a visual designer will be used for the Netbeans tool that by defualt will generate a new Project as the result of the initial structure.