Can someone sum me up when transponders are active by default on civilian and then military ships, depending of the solar system the ship is in? Because I think it deactivate automatically in unclaimed systems e.g.
A ship with an active transponder will show up on the system map, regardless of current sensor settings. Much like wrecks or planets, if you're in the same system you know they're there. They are off by default as far as I know. You can see your ships because they are yours and you see them regardless. Civilians can be ordered to turn Transponder off in some systems under the contacts tab of the galactic map I think, or at least you could in VB6.
EDIT: there is no option anymore regarding civilians transponder off in some systems.