Listening Post Capability Questions

Hey! :)<br /><br />I was wondering about the efficacy of a Sathar planet-based Listening Post? What kind of capabilities would such a thing have, or to clarify, what would be the range (in light years) from which it could logically spy on a target? Would it be positioned to spy on a specific target or would it have an ability to data mine radio transmissions from omidirectional sources...or would it do both? Would it be equiped to visually spy using long range telescopes maybe (or probes)? Or simply rely on intercepting radio communications?<br /><br />Any information would be helpfull!