JSR-179API provider reset to stop GPS location activity

[nicholso]

Hi

I have coded two location applications - one that uses getLocation() for synchronous calls to GPS - second that uses LocationListener for subscribing to periodic location updates.

I want each application to stop the internal GPS module location activity after a set time, such as few minutes, to save battery life. I am using the Nokia Energy Profiler application to test the applications on Nokia E90.

1) The first application works fine - after the getLocation has returned, I call provider.reset(), GPS module location activity stops and battery life is saved.

2) The second application doesn't allow GPS module location activity to stop if there is already a GPS satellite fix, causing Nokia E90 battery life to drop to below 10 hours. It uses the framework TouristRoute JSR179API example from Forum Nokia. I stop the periodic listener updates and reset the provider by calling:

provider.setLocationListener(null,-1,0,0);
provider.reset();

Then this application stops receiving GPS updates from the LocationListener, however with a existing GPS satellite fix the GPS location module continues consuming power until I exit the application (if there was no GPS satellite fix then the GPS power consumption stops after 30-45 seconds as expected and battery life is saved) Any suggestions how to stop the GPS location module activity without having to exit the application?

Thanks
Guy

[nicholso]

This is a simplified version of the second application using the location listener method. I also tried calling the functions in reverse order with still the same problem that the GPS power consumption does not drop, e.g:
provider.reset();
provider.setLocationListener(null, -1, 0, 0);

/* Here is sample code which compiles and runs on emulator and E90
 * StopGPS() stops the location updates, but if the GPS module 
 * has a satellite fix, power consumption does not drop...
 */
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.location.*;
import javax.microedition.io.*;
import java.io.*; 

public class MyMidlet extends MIDlet implements CommandListener, LocationListener { 
    
    Command Exit = new Command("Exit",Command.EXIT,0);
    Command StopGPS = new Command("Stop GPS", Command.ITEM, 0);
    Command StartGPS = new Command("Start GPS", Command.ITEM, 0);
    
    public Form f=new Form("LocationListener"); 
    
    public LocationProvider provider;
    public Location location;
    public QualifiedCoordinates qc;

    public void startApp() {
        // test whether location API is supported
         if (System.getProperty("microedition.location.version") == null) {
            destroyApp(true);
            notifyDestroyed();
        }  
                
        f.addCommand(Exit);
        f.setCommandListener(this);
        Display.getDisplay(this).setCurrent(f);  
        StartGPS();   
    }
    
    public void pauseApp() { }
    
    public void destroyApp(boolean destroy) { }
    
    public void commandAction(Command c, Displayable s)  {
        if (c == Exit) {
            destroyApp(true);
            notifyDestroyed();
        }
        if (c == StartGPS) {
            StartGPS();
        }
        if (c == StopGPS) {
            StopGPS();
        }
    }
    
     public void StartGPS() {
        try {
            provider = LocationProvider.getInstance(null);
            provider.setLocationListener(this, -1, 0, 0);

            f.removeCommand(StartGPS);
            f.addCommand(StopGPS);
            f.deleteAll();
            f.append("Searching...");
        } catch ( SecurityException e ) {  // added catch 22/8/2008
            f.removeCommand(StopGPS);
            f.addCommand(StartGPS);
        }catch (Exception e ) {
            f.append("Exception in StartGPS()");            
        }
    }
     
     public void StopGPS() {
        try {
            provider.setLocationListener(null, -1, 0, 0); // here   
            provider.reset();  // here

            f.removeCommand(StopGPS);
            f.addCommand(StartGPS);
            f.deleteAll();
            f.append("Location listener stopped.");
        } catch (Exception e ) {
            f.append("Exception in StopGPS()");   
        }
    }
    
    public void locationUpdated(final LocationProvider prov, final Location loc) {
        new Thread() {
            public void run() {
                if (loc != null && loc.isValid()) {
                    qc = loc.getQualifiedCoordinates();
                    
                    f.deleteAll();
                    
                    f.append("Latest update:\n");
                    f.append(" Lat: "+ qc.getLatitude() +"°\n");
                    f.append(" Lon: "+ qc.getLongitude() +"°\n");
                    
                  } else {
                    f.deleteAll();
                    f.append("Location null or invalid object:\n");
                }
            }
        }.start();
    }

    public void providerStateChanged(LocationProvider prov, int newState) {
    }  
}

[nicholso]

Further testing - this problem occurs with both Assisted-GPS enabled or disabled. My working assumption is that when the Nokia E90 GPS & JSR-179 implementation has a satellite fix, then the location provider GPS module won't power down and won't release references to my application with provider.reset() and setLocationListener(null,..) function calls until the application location listener object is destroyed which only happens for sure on application exit... This assumption then implies the E90 implementation of GPS and JSR-179 doesn't work as described in the JSR-179 API

[r2j7]

Hello nicholso,

..causing Nokia E90 battery life to drop to below 10 hours.

what's the (approximate) value for battery life which you receive when you run the MyMIDlet app?

Regards,
r2j7

[nicholso]

Hi!

All these tests below are with a Nokia E90 (CE marked unit)

with MyMidlet running and location updates being received ... after A-GPS has finished the cellular data call..., Nokia Energy Profiler indicates a battery life of 8 hours:-
http://www.geocities.com/guy_nich/GPSShot01.png

If there is no GPS satellite fix and StopGPS() is called, the battery life improves after thirty seconds as expected, and power consumption eventually drops to a low standby level:-
http://www.geocities.com/guy_nich/GPSShot02.png

But if there is GPS satellite fix and StopGPS() is called, power consumption stays around 0.5W and does not drop (eventually causing a battery life indication of under 12 hours). This condition is the error I have found - the GPS module does not power down for this case.
http://www.geocities.com/guy_nich/GPSShot03.png

If the MyMidlet is exited, then GPS module will power down whatever the satellite fix status.

Thanks, Guy

I also rewrote the application to see if the way how MyMidlet creates the location listener object could be the cause of this error (..this code creates a new object each time StartGPS() is called..), but still this error is observed

package utmMain;
/*
 * UTMloclist.java
 * Created on 09 January 2008, 11:59
 * @author  nicholso
 * @version 0.2
 */
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.location.*;
import javax.microedition.io.*;
  
import java.io.*; 

public class MyMidlet extends MIDlet implements CommandListener { // 0.2 removed LocationListener
    
    Command Exit = new Command("Exit",Command.EXIT,0);
    Command StopGPS = new Command("Stop", Command.ITEM, 0);
    Command StartGPS = new Command("Start!", Command.ITEM, 0);
    
    public Form f=new Form("Listener"); 
    
    public LocationProvider provider;
    public Location location;
    public LocationListener myListener;
    public QualifiedCoordinates qc = null;
    double lat = 0.0;
    double lon = 0.0;
    float acc = (float)0.0;
    long timeMS = 0;
    
    public void startApp() {
               
        f.addCommand(Exit);
        f.setCommandListener(this);
        Display.getDisplay(this).setCurrent(f);
        
        // test whether location API is supported, if so then find a provider and start the application
        if (System.getProperty("microedition.location.version") == null) {
            f.append ("Location API not supported");
        } else {    
            try {
                StartGPS();  
            } catch ( Exception e  ) {
                f.append("Provider exception");
            }
        }
    }
    
    public void pauseApp() { }
    
    public void destroyApp(boolean destroy) { 
        provider.setLocationListener(null, -1, 0, 0);     
        provider.reset();
    }
    
    public void commandAction(Command c, Displayable s)  {
        if (c == Exit) {
            destroyApp(true);
            notifyDestroyed();
        }
        if (c == StartGPS) {
            StartGPS();
        }
        if (c == StopGPS) {
            StopGPS();
        }
    }
    
     public void StartGPS() {
        try {   

            provider = LocationProvider.getInstance(null); // least restrictive criteria...         

            // 0.2 create new listener object each time StartGPS() is called
            myListener = new MyLocationListener(); 
            provider.setLocationListener(myListener, 2, 1, 2);
            
            f.removeCommand(StartGPS);
            f.addCommand(StopGPS);
            f.deleteAll();
            f.append("GPS started...");
        } catch (Exception e ) {
            // f.append("Exception in StartGPS()");            
        }
    }
     
     public void StopGPS() {
        try {
 
            provider.setLocationListener(null, -1, 0, 0);     
            provider.reset();  
            
            f.removeCommand(StopGPS);
            f.addCommand(StartGPS);
            f.deleteAll();
            f.append("Last known location:\n");
            showLocation();
            f.append(" Location listener stopped.\n");
        } catch (Exception e ) {
            f.append("Exception in StopGPS()");   
        }
    }
     
    public void showLocation() {
        f.append(" Lat: "+ lat +"°\n");
        f.append(" Lon: "+ lon +"°\n");
      }

/* 0.2 now MyLocationListener placed inside class - e.g.: a separated object from MyMidlet */

    public class MyLocationListener implements LocationListener {     
        public void locationUpdated(final LocationProvider prov, final Location loc) {

            new Thread() {
                public void run() {
                    if (loc != null && loc.isValid()) {
                        qc = loc.getQualifiedCoordinates();
                        lat = qc.getLatitude();
                        lon = qc.getLongitude();
                        acc = qc.getHorizontalAccuracy();
                        timeMS = loc.getTimestamp();

                        f.deleteAll();

                        f.append("Latest location:\n");
                        showLocation();
                    } else {
                        // if Location is not valid...
                        f.deleteAll();
                        f.append("Last known location:\n");
                        showLocation();

                        int test = prov.getState();
                        if (  test == LocationProvider.AVAILABLE )
                            f.append(" Available. Searching...\n");                        
                        else if ( test == LocationProvider.TEMPORARILY_UNAVAILABLE )
                            f.append(" Temporarily unavailable...\n");
                        else
                            f.append(" Out of Service...\n");     
                    }
                }
            }.start();

        }

        public void providerStateChanged(LocationProvider prov, int newState) {
        }  
    }
    
}

[nicholso]

I repeated the tests with an N95 (CE marked unit), and same error is observed: if the function calls are made with an existing GPS satellite fix, the battery life is only 8hours and power consumption is around 0.44W.
http://www.geocities.com/guy_nich/n95.png

If there is no satellite fix, the power consumption drops to normal standby levels.

[balagopalks]

Hi nicholso,

I am able reproduce the same in E90. But saw that if we exit he MIDlet, the battery life is getting improved.

For me the EnergyProfiler takes some time to give a stable graph.

Regards
Gopal

[sgreenhill]

Hi,

I have the same problem on my Nokia 6110 Navigator.

Did anyone find a workaround? I tried periodically calling getLocation, allowing the GPS to power down between samples. At least on my Nokia 6110, getLocation seems to be quite buggy and will eventually hang the MIDlet.

Details here

Cheers, Stewart

[rosenholzer]

Hi !

I have the same problem.
Could not solve it.

Neither

provider.reset()

nor

provider.setLocationListener(null, 1, -1, -1)

helps on

Navigator 6110

regards

Michael

[nicholso]

There is a "known issue" article in the Developers Wiki about this issue.

http://wiki.forum.nokia.com/index.ph...d_battery_life

For my application, exiting the midlet does not provide a solution. I have not found a proper work-around to allow an active midlet using location listener to start and stop the GPS module (stop here means "power-down").

[r2j7]

Hello nicholso,

..For my application, exiting the midlet does not provide a solution.

Just to check: I've noticed that the battery level normalized rather slowly after exiting the MIDlet.

Have you tried to test this after some period (15 seconds or so) from exiting the MIDlet?

Regards,
r2j7

[nicholso]

hi r2j7

Sure - the GPS powers-down when the user exits midlet. Yes - it does take time like 15-30 seconds.

But my comment was this doesn't provide a solution for developer applications... e.g.: the use case where -within- the application the user can turn off gps, or the application can power off gps after inactivity of set time.

Please try google s60 maps application or Nokia Location tagger from Nokia's beta labs ... Each powers down GPS within the application and doesn't require user to exit the application. This saves precious battery life whilst the user can continue to use the application.

By contrast the current J2ME implementation requires that if user/J2ME application wants to power down GPS, then user/J2ME application MUST exit the midlet.

Thanks for trying to help, but the real issue is within the J2ME implementation,
Guy

[ryback3]

We have a project with JSR-179 API on N95,we have same problems with you about power consumption;

We have question marks about gps system on mobile phone;

1-Gps on mobile phone works everytime ? or it will be activited when applications begin getting info from gps ?

2-In our application when we set locationListener 5 minutes interval,what will be about power consumption,is it more different from setting loationlistener 2 seconds?

3-I have read an article that says if you don't get info from gps during 10 minutes it will turn sleep mode is that true? If that is true ,when changing over sleep mode to active mode,will the power consumption peak?

thanks,

[eritreo]

Have you tried to test (2) and (3) with energy profiler?

Bye,
Eritreo.

[ryback3]

I couldn't try because I'm working on s60 emulator and can't install energy profiler on it for testing, I couldn't find solution,researched too many documents about gps power consumption