Blackberry GPS and BlackBerry Maps Manual - Página 5

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Development Guide

GPS location information

You can create a BlackBerry® device application to display the current latitudinal and longitudinal position of a BlackBerry device.

Depending on the mode for getting location information that you specify, the BlackBerry device application can also display

information such as the speed and route information. To create a BlackBerry device application to get location information, you

can use the Location API for Java® ME in the javax.microedition.location package (JSR 179).

The time it takes to retrieve the location of the BlackBerry device for the first time depends on several factors, such as the mode

for getting location information and the GPS signal strength. In autonomous mode, typical times are less than 2 minutes. In

assisted mode, typical times are less than 30 seconds.

To retrieve and display GPS location information, the BlackBerry device must support GPS technology and a valid SIM card must

be inserted in the BlackBerry device.

Specifying the source of GPS location information

GPS location information might be unavailable if the BlackBerry® device cannot receive signals from GPS satellites. This situation

can occur when something is obstructing the signals, such as buildings or dense clouds.

To specify the source of GPS location information, you specify the mode by creating an instance of the

javax.microedition.location.Criteria class, invoke the appropriate set methods, and then pass the instance

to LocationProvider.getInstance().

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cell site: Use this mode to get location information from cell site towers. This mode allows a BlackBerry device application

to retrieve location information faster than the assisted and autonomous modes. However, the accuracy of the location

information is low-level and does not provide tracking information such as speed or route information. Using this mode

requires wireless network coverage and that both the BlackBerry device and the wireless service provider support this mode.

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assisted: Use this mode to get location information from satellites using a PDE. This mode allows a BlackBerry device

application to retrieve location information faster than the autonomous mode and more accurately than the cell site mode.

To use this mode requires wireless network coverage, and the BlackBerry device and the wireless service provider must

support this mode.

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autonomous: Use this mode to get location information from the GPS receiver on the BlackBerry device without assistance

from the wireless network. This mode allows a BlackBerry device application to retrieve location information that has high-

accuracy, and does not require assistance from the wireless network. However, the speed at which this mode retrieves

location information is slower than the other modes.

Get location information from cell site towers

Create an instance of a Criteria object.

Criteria criteria = new Criteria();

GPS location information