A listening post was a specialized facility equipped with specialized and highly sensitive full-spectrum transceivers, subspace antenna, and HoloNet transceivers for the purposes of eavesdropping on communications.
Due to the incredibly large proportions of such sensitive listening equipment, listening posts were typically capable of monitoring and sifting through subspace and HoloNet communications within entire sectors, as was the case with Skytop Station. Because of this, a listening post was usually located in remote and deserted places where militaries could strategically listen in on their enemies or watch for invading enemy forces.
During the Clone Wars, the Grand Army of the Republic maintained listening posts at remote locations of the Outer Rim Territories to watch for invasion fleets of the Confederacy of Independent Systems. One such station, on Rishi moon, was overrun by Separatist BX-series droid commandos. An "all clear" signal was transmitted constantly; if there was an interruption in the signal, the Republic would consider it a signal that Separatists had either arrived in the system, alerting the clones on staff to stop the signal, or had destroyed the station itself as part of an invasion. The station was eventually destroyed, alerting Republic forces of the invasion.
The Confederacy of Independent Systems also had listening posts on different planets. One such was Skytop Station, which floated above Ruusan 2. Eventually, it was destroyed by the Republic. The Separatists also had listening posts on Geonosis.
Nalgol once worked in a distant Imperial listening post. During the Galactic Civil War, the Alliance to Restore the Republic attempted to set up a listening post on a jungle planet, although they were discovered by the Imperial forces stationed there. The New Republic Defense Fleet had a small listening post on Utharis. ExGal-4 on Belkadan was a type of listening post set up to monitor space for signs of extra-galactic activity. The Yuuzhan Vong were also known to have listening posts throughout the galaxy.
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