a.cs

void LocationChanged(object sender, PositionEventArgs e)
{
  if (stopWatch == null) {
    stopWatch = Stopwatch.StartNew();
  }
        var position = e.Position;
        if (UnixTimeStamp > previousUpdateTime + MinUpdateTime) {
            stopWatch.Stop();
            Log("location: ({0}, {1}), lapsed time: {2}", position.Latitude, position.Longitude, stopWatch.ElapsedMilliseconds);
    previousUpdateTime = UnixTimeStamp;
        }
        else {
            skippedLocationsCount++;
            Log("location skipped count: {0}", skippedLocationsCount);
            if (!stopWatch.IsRunning) {
                stopWatch.Restart();
            }
        }
}