Thank you for the quick changes.
Unfortunately this doesn't solve the problem.
After setting DispatchPropertyChangedEvent to true in the constructor of the viewmodel the program seems to be deadlocked as soon as the first property is changed in the timer callback function.
After i changed the line
_dispatcherService.Invoke(() => base.RaisePropertyChanged(sender, e));
in method RaisePropertyChanged in ViewModelbase to
_dispatcherService.BeginInvoke(() => base.RaisePropertyChanged(sender, e));
everything works as expected.
Could this be an option ?