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I believe this is already in the base game - you can see the sensor circles of other fleets (for how they can detect you) in the color of their faction.
yea i have noticed them, but the so feint and brief that if they more than couple signals then your going to miss them unless you pause at exact right moment.
I was kind of hoping for something more obvious so you can litterally study the scan lines to fine holes in system patrols, and preferebly toggle on/off so it not spammy when your not sneaking, I even accept it if it was only available with certain equipment or skills so sake of game balancing etc.
its really awsome those asteroid belts etc are not just for show and can hide you, things like that can make stealth very viable which is angle i going for
Beside that tho, the game seem really awsome, and sure look forward to seeing what this game be like when it officially leaves alpha