Actually what Wr3nd said is not far from being factually correct. Hypothetically, if I were asked my professional opinion of the FSS (or DSS) in the context of the ED Universe, I could only characterise it as a child's toy, or at best a child's learning toy. Why? Because any electrical engineer would simply take the FSS and add basic 20th century tech to automate it. There would be no antiquated tuning dial, no zoom in/out buttons.
The FSS mechanics would fit perfectly in a 1960's Earth setting. But in ED, or any setting past 1990 Earth? Nope, it's absurd to think that thousands of explorers are out in the black manually fiddling with their... ahem... dials.
And if you ask any other electrical engineer (or related technologist), I think you'd get the same professional opinion.