Motorola i325 Spezifikationen PDF herunterladen (Seite 108)

iDEN i325 J2ME™ Developers’ Guide

Page 108

2004 Motorola, Inc.

requesting a new fix. After this pause, the application can continue requesting fixes at its

normal frequency.

• GPS subsystem requires about one second to calculate a new fix, so any request for a

new fix during this one-second period may result in the exact same position information

including the time stamp. Therefore it is recommended that an application request a new

position no more than once per second.

• If an application needs continuous position, use "delay=low" once and "delay=high"

thereafter even if the first fix does not succeed. The reason for this is because of network

failures. When there is a network failure, there is a 12 to 24 second communication timeout

from the LES.

• Use "delay=no" if the application needs only the cell latitude and longitude. This does not

use AGPS chip on device.

• Applications must handle all response codes returned by the AggregatePosition

getResponseCode() method and the PositionConnection getStatus() method.

getStatus() provides the connection’s status after the fix and user interaction status

with regards to permission. getResponseCode() provides information about the position

itself.

• Applications must always check the speed uncertainty value before using speed and

heading. Although it is counter-intuitive, the presence of speed uncertainty denotes that the

speed and heading value are accurate. Therefore, if a call to hasSpeedUncertainty()

returns true, the speed and heading returned by the API are valid.

• If an application calls getPosition(String name) method with the "fix=extended"

tag, this method will return accurate velocity and heading direction; however, there is a

time penalty since it takes longer to calculate the accurate velocity and heading direction

when the method is called.

• The method PositionConnetion.getStatus() provides the status of the connection

when the method PositionConnection.getPosition() was called. Whereas,

AggregatePosition.getResponseCode() returns the detailed response code

• Getting a position for the first time after the phone powers on is referred as a “cold start”. A

position retrieved within ten seconds of the previous fix is referred to as a “hot start”. A

position retrieved after ten seconds of the previous fix is a “warm start”. After 1 hour since

the last fix will set the device back to “cold start”. Therefore, “hot start” is the quickest way

of retrieving a fix.

• For i325 it is highly recommended that antenna remain extended all the time while getting

fixes.

• There is a battery impact when the NMEA API is used heavily.

• If the application will need NMEA data again in less than 10 seconds, there is no value in

calling stopNMEASentence() because the GPS chip will stay on for 10 seconds after

calling stopNMEASentence().

• First call of getNMEASentence() will turn on the GPS chip and it stays on until application

calls stopNMEASentence().

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