The following is a general reference for common human sensor technologies.
Short range using various forms of visual technologies and transponder registrations to identify vessels. While limited to a fairly short range they’re fast and their accuracy is nearly 100%.
Effective Range: ~.5ly
Short to Mid range, detecting and analyzing the distinct EM signatures of different power systems and engine types. While having fairly substantial ranges and a high degree of accuracy they are only effective on stations and outposts in order to filter EM signatures against background noise.
Effective Range: ~250ly
Long range analyzing shape and mass of ships over long range by measuring the gravimetric distortion caused by the vessel. These sensor types are highly reliable as they are not affected by common interference such as EM and Nebula static. They are also difficult to fool as it is nearly impossible to mask gravity displacement. The drawback is that they can only reliably detect ships or fleets large enough to cause gravity fluctuations.
Effective Range: ~1000ly
Networks of probes that use combinations of various sensor types to cover large areas of space far outside stationed sensor arrays. The main drawback is that they are prone to disruptions from common cosmic hazards such as micro meteor impacts and thus require regular maintenance.
Internal systems used to detect living beings inside facilities through a variety methods. Usually using registered unique bio-electric or neural signatures but pheromone and air displacement sensors are also used for tracking, in particular with alien visitors.