Ok, so it sounds like I'm the lone dissenting voice.
When the resolution stuff was put in, the technobabble associated with it was that there was some difference in the signal (e.g. pulse repetition rate) that the emitter gave out that caused the resolution differences. This difference in signal should be detectable by the target, i.e. it is reasonable that the target should know the resolution of the emitter.
At the same time, I don't like the crisp certainty of knowing exactly when the bad guy can pick you up on his actives. So how about this: Add the EM (passive) level to the design of an active sensor, with the range increasing like sqrt(sensor_rating/lowest_tech_sensor_rating). What this represents is that there are two components to an active sensor: the emitter (active strength tech) and the receiver (EM tech). Better passive tech should mean that you can build better receivers, hence the range bonus. In reality, signal should drop off like the fourth power of the distance (inverse square law each way: out and back), but that's such a steep drop that it probably wouldn't be noticable; the sqrt is a compromise between the fourth root and a linear drop. (If you wanted to be drastic, you could have the range be proportional to the passive rating - that would make it even more uncertain.)
With this suggestion, two good things happen (from my point of view):
1) The target has a feel for the gross characteristics of the active emitter, but still is fuzzy on exactly where the detection threshold is. This is my impression of the way things currently work both for radar and sonar.
2) The design choices for active emitters become richer, and there are other ways to improve actives rather than just cranking up on the active sensor research track.
One other thing: I think that my response to this thread is in alignment with my desire to make passives able to identify ships/races (in another thread). If you look at current military signals intelligence (e.g. radar and sonar) it seems like it's all passive, rather than active. Submarines trail other ships trying to get a passive "fingerprint". Elint planes fly around just outside excercises trying to detect characteristics of active emitters. In addition, submarines can launch attacks on other ships without ever going active. Passive intelligence techniques for identifying emitting platforms are very sophisticated; I'd rather see their abstractions in Aurora move in the direction of gaining more information about the emitter, rather than less. On the other hand, a big drawback in passive techniques is range uncertainty - it would be nice if there were an easy-to-code and easy-to-represent way of putting that location uncertainty into passive contacts. At present, I think that abstraction is handled by the requirement that you need an active contact in order for its location to be "good enough" to fire at. Since we don't have another way to abstract the fuzziness, this seems a reasonable way to require people to include active sensors in their designs.
John