I have a quick silly question for a first-timer at assembling circuits. I have a circuit with a photodiode input and a BNC/coaxial output to a scope. The circuit diagram is below. In assembling this circuit, I'm not sure where to ground to. I've put it in a metal enclosure. One book says that "grounding" usually means connecting it to the metal enclosure. Should I do that? Another source seems to suggest that coaxial cables provide the ground via the scope or whatever they are connected to. Which would mean that I don't need the "ground" in the circuit diagram. I've drawn up a quick visual to clarify the question (notice the question mark). Thanks!