title: how to stimulate a lowerpass filter in simulink?
body: <p>I should stimulate how the lowpass filter work exactly with simulink so i create a signal  generator f=50 hz and i make a lowerfilter and after that i want to see it so the only tool that i found it is spectrum analyzer but when i simulate i get two errors 
  Sorry if it's not really explain because i'm beginner in simulink 
  <img src="https://i.stack.imgur.com/0y7HN.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/U8rok.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/N12bJ.png" alt="enter image description here"></p>