What does upgrading the KWS scanner do?

[Daud]

Besides, in some cases, improving the range.

 

[Feldspar]

It improves the range.

There's a rounding error on the description, so despite it not looking that way, the range increases by 0.5 Km per grade increase.

 

[Wizz]

Besides, in some cases, improving the range.

you already gave the answer.
It improves the range. Not in some cases, but in all cases.
And it improves the insurance cost of your ship

 

[Daud]

Not really- since it displays the same number and doesn't specify the improvement.

 

[Wizz]

Not really- since it displays the same number and doesn't specify the improvement.

you're right, the description is not clear. But as Feldspar said, it goes with 0,5km increments.
And the system rounds down the halves.
So 3,5 it displays as 3km range. But in reality it's 3,5km.