如何通过 GPS_PROVIDER 获得更高的准确性

Question

我有一个挑战任务是要获得非常高的准确度。所以我正在使用 GPS_PROVIDER。但我的代码得到不正确的准确性。有时它会显示距离我当前位置 10 到 50 米。有时它会向我显示 距我当前位置 5 到 15 米的距离。我已经测试了 XOLO 和 Sony 两种设备。我已经解决了这些问题，但无法解决。 这是我的代码：-

@Override
protected void onResume() {
    super.onResume();

    if(mMap!= null)
        mMaprivate LatLng geo;
map.clear();

    locationManager = (LocationManager)this.getSystemService(Context.LOCATION_SERVICE);             
    mFragment = (SupportMapFragment) this.getSupportFragmentManager().findFragmentById(R.id.map);
    mMap = mFragment.getMap(); 
    }
   setListener();
 }

private void setListener() {    
    System.out.println("setListener()  locationListener = "+locationListener);
    if(locationListener != null){
        clearListener();
    }

    Toast toast = Toast.makeText(this, this.getResources().getString(R.string.maps_loading), Toast.LENGTH_LONG);
    toast.show();   
    private LatLng geo;

    locationListener = new CustomLocationListener();

    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    //criteria.setAccuracy(Criteria.ACCURACY_HIGH);
    criteria.setPowerRequirement(Criteria.NO_REQUIREMENT);
    String bestProvider = locationManager.getBestProvider(criteria, true); 
    Toast.makeText(this, "bestProvider= "+bestProvider, Toast.LENGTH_SHORT).show();
//  locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
   locationManager.requestLocationUpdates(bestProvider, 0, 0, locationListener);

    handler=new Handler();
    timeoutTask = new TimeoutTask(locationListener);
    handler.postDelayed(timeoutTask, 50*1000);
}

private void clearListener(){
    if(locationListener != null){
        locationManager.removeUpdates(locationListener);
        locationListener = null;
    }
}

private void gotLocation(Location location){
    loc = location;
    System.out.println("getLocation = "+location.getLatitude());
 //   Toast.makeText(getBaseContext(), "new Lat = "+location.getLatitude(), Toast.LENGTH_LONG).show();
}

public class CustomLocationListener implements LocationListener {
    private boolean isCompleted = false;

    public CustomLocationListener() {}

    @Override
    public void onLocationChanged(Location location) {
        isCompleted=true;

        System.out.println("onLocationChanged 1");

          // Called when a new location is found by the GPS location provider.
          if(isBetterLocation(location, loc)){
            //  Toast.makeText(getBaseContext(), "yes", Toast.LENGTH_LONG).show();
              System.out.println("onLocationChanged 2");
              gotLocation(location);
          }
          System.out.println("onLocationChanged 3");
          clearListener();
          setUserPoint();
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) { }

    @Override
    public void onProviderEnabled(String provider) { }

    @Override
    public void onProviderDisabled(String provider) { }

    public boolean isCompleted() {
        return isCompleted;
    }private LatLng geo;

}   
private LatLng geo;

 public class TimeoutTask implements Runnable {

    private CustomLocationListener listener;

    public TimeoutTask(CustomLocationListener listener) {
        this.listener=listener;
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        if (listener == null || listener.isCompleted()) {
            Log.e("provider", "completed");
       }
        else {
            Toast.makeText(ScorecardMapViewActivity.this, "We were unable to find your position, please try again", Toast.LENGTH_LONG).show();
            Log.e("provider", "timeout");
            clearListener();
            setUserPoint();
            if(goToScorecardStep3WithLocation) finish(); 
        }
    }
}



protected boolean isBetterLocation(Location location, Location currentBestLocation) {
    if (currentBestLocation == null) {
        // A new location is always better than no location
        return true;
    }

    // Check whether the new location fix is newer or older
    long timeDelta = location.getTime() - currentBestLocation.getTime();
    boolean isSignificantlyNewer = timeDelta > TWO_MINUTES;
    boolean isSignificantlyOlder = timeDelta < -TWO_MINUTES;
    boolean isNewer = timeDelta > 0;

    // If it's been more than two minutes since the current location, use the new location
    // because the user has likely moved
    if (isSignificantlyNewer) {
        return true;
    // If the new location is more than two minutes older, it must be worse
    } else if (isSignificantlyOlder) {
        return false;
    }

    // Check whether the new location fix is more or less accurate
    int accuracyDelta = (int) (location.getAccuracy() - currentBestLocation.getAccuracy());
    boolean isLessAccurate = accuracyDelta > 0;
    boolean isMoreAccurate = accuracyDelta < 0;
    boolean isSignificantlyLessAccurate = accuracyDelta > 200;

    // Check if the old and new location are from the same provider
    boolean isFromSameProvider = isSameProvider(location.getProvider(),
            currentBestLocation.getProvider());

    // Determine location quality using a combination of timeliness and accuracy
    if (isMoreAccurate) {
        return true;
    } else if (isNewer && !isLessAccurate) {
        return true;
    } else if (isNewer && !isSignificantlyLessAccurate && isFromSameProvider) {
        return true;
    }
    return false;
}

private LatLng geo;

private void setUserPoint() {
    if(!goToScorecardStep3WithLocation) {
    if(loc != null) {

         if(handler != null) { System.out.println("removed timeout task from handler");
            handler.removeCallbacks(timeoutTask); }

        geo = HelperUtil.getLatLng(loc);
        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(geo, 18));
        mMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);

        System.out.println("loc.getLatitude() = "+loc.getLatitude());
        System.out.println("loc.getLongitude() = "+loc.getLongitude());

        // your current position show.
         mMap.addMarker(new MarkerOptions().title("Player").position(geo)
        .icon(BitmapDescriptorFactory.fromResource(R.drawable.map_point)));
}
}
}

请任何一位专家帮助我。您的帮助将非常有帮助。 谢谢！

更新：-

我注意到我是否在同一个地方。有时我会得到长小数点，有时会得到小数点。由于小数点，计算距离是否有任何影响？我正在计算院子里的距离。

当前位置 = 纬度 28.65361000000004 长 = 77.4122733333333

以前的当前位置点（这是同一个地方，但纬度/经度不同）

纬度 = 28.653685000000003 长 = 77.4123083333334

我有 8 码的距离。我认为一些问题可能是由于长或小的数字点。 有没有办法让我们只得到长小数点？

Answer 1

消费类 GPS 接收器在 95% 的情况下具有 2.5-6m 的精度，对于移动设备，您无法提高它。

如果您静止不动（通过用户交互告知静止开始和静止结束），您可以计算平均位置。
尤其是在静止不动时，GPS 芯片的精度会降低一些，因为多普勒频移只能在移动时使用。

要计算设备的准确度，您应该采取一些措施，计算平均位置，并计算每次测量到该平均位置的距离。 那么这应该给出3-6m之间的值。

您写道，您希望在静止不动时两个位置之间的距离为 0 米。
但这不适用于 GPS。由于对流层的波动条件，信号延迟略有变化，导致静止不动时的跳跃位置。

如果你启用了 iOS 默认使用的静止过滤器，你只会得到 0m。 Android 中也应该有可能启用这样的过滤器（例如，通过将距离阈值设置为高于 0 的值）。

Answer 2

在OnLocation 方法中检查定位精度，如果不合适，下次调用OnLocation 通常会更准确。更高的准确性需要更多的工作。您已经看到谷歌地图在该位置周围显示了一个圆圈，并且可能看到它的大小减小了。圆的半径取决于位置精度，它是 Location 的一个属性。

下面的方法效果很好。我在开车、骑自行车、遛狗和哈雷时对它进行了广泛的测试。它会过滤掉进入 Mcd's 并让位置出现在 Mcd 的 wifi 提供商所在的德克萨斯州以及相距 100m 位置的那些讨厌的位置。

@Override
public void onLocationChanged(Location location) {


    if (!location.hasAccuracy()) {
            return;
        }
        if (location.getAccuracy() > myDesiredAccuracy) {
            return;
        }

//blah what your app does...

    isCompleted=true;

    System.out.println("onLocationChanged 1");

      // Called when a new location is found by the GPS location provider.
      if(isBetterLocation(location, loc)){
        //  Toast.makeText(getBaseContext(), "yes", Toast.LENGTH_LONG).show();
          System.out.println("onLocationChanged 2");
          gotLocation(location);
      }
      System.out.println("onLocationChanged 3");
      clearListener();
      setUserPoint();
}

注意：有时您会遇到无法获得良好 GPS 接收的死角。这些是由于建筑物内、电源线、视线、高速公路中断、建筑物中未映射的 wifi、其他发射无线电信号的设备干扰 GPS 卫星接收而引起的。基本上任何会干扰无线电接收的东西都会干扰 GPS。