If sensors are starships eyes, its communication systems are its ears and its voice. Through personal communicators, planetary broadcast stations, and the Federations subspace relay network, a starship can use its subspace radio and other communications devices to contact just about anyone in the quadrant.
Subspace radio waves propagate at Warp 9.9997, far faster than the fastest conventional drive starship, but not always fast enough to allow instantaneous communication with distant locations. Sometimes communications lags of hours or days result, but in most situations any lags are minimal. However, subspace radio waves cannot travel more than 22.65 light-years without degrading to unacceptable levels. Thus, networks of manned and unmanned subspace relay stations are required for communication across the quadrant. No existing or projected Federation technology can overcome this “97/22” limit (though the Borg, at least, seem to be able to use interplexing beacons to project messages farther than 22.65 light-years).
Recent upgrades to Starfleet subspace relay network incorporate hyperspace interplexing beacon technologies, similar to that used by the Borg. These enhanced relay stations allow for subspace radio to be compressed and transmitted in a special transient subspace domain (perhaps using a sub-quantum slipstream of transwarp corridor based technology), allowing for nigh instantaneous transmissions across the Federation and beyond. Similar technological breakthroughs have been installed on Starfleet’s most advanced ships, including the Premonition, Republic, and Ascendant-classes of Starship that work as mobile relay stations. In the case of the Ascendant-class, a Hyperspace Projection antenna is built into the ships super structure to allow for transmissions across vast distances (for example, from positions in the Delta quadrant to locations in the Alpha quadrant). They do so by a combination of interplexing transceivers built into all new types of starship classes, which reflect off the hyperspace relay networks deployed in the farthest areas of Federation space, beyond, and throughout the Federation. Each relay station emits coherent gravimetric waves, allowing each station to simulate a ‘pulsar’ of which the original Pathfinder project used gravimetric occurrences in pulsars to keep in constant contact with the USS Voyager on a monthly basis. These stations gravimetric emitters can be toned to simulate the conditions needed for hyperspace broadcasting, allowing Starfleet to use the pathfinder project methods on a far more controlled basis.
Most ships have medium-powered subspace transceivers for ship-to-ground communications, and ultra-high-powered transceivers for ship-to-ship and long-range communications needs. As aforementioned, from personal communicators to starship transceivers, have been upgraded with various levels of interplexing beacons, allowing them much farther and cohesive transmitting ranges than were possible before, as well as far more stable, allowing them to cut through interference older subspace radio waves could not. The transceivers are located at various points within the ship to provide maximum coverage. Medium-powered transceivers have a maximum range of about 60,000 kilometers, and new interplexing beacons of up to 10-lightyears. Ultra-high-powered transceivers have a maximum range of 22.65 light-years, and enhanced hyperspace antennae are ranged thus far at 10,000 light-years, and possibly more.
Many Starfleet communications contain confidential, classified, or secret information which Threat species must not be allowed to overhear. To prevent such breaches of security, a secured channel may be used for communicating. A secure channel uses Starfleet’s advanced encryption algorithms to prevent outsiders from understanding the transmission. Every communication system has a security rating, representing its ability to overcome espionage (cryptography).
Every ship’s computer is equipped with a universal translator (UT). This subroutine analyzes spoken or written language, compares it to its database (which holds thousands of languages), and in almost all cases makes an instant two-way translation—each participant in the conversation hears or reads the other person’s speech in her/his native tongue. However, the use of the UT is obvious; the speech comes from it, not the person speaking it. If a language is not in the UT’s, database, it can analyze the language and usually delivers a reasonable translation after no more than a half an hour of exposure (the more speech or writing it has to analyze, the less time translation usually takes, though the exotic nature or complexity of some languages require more processing time.).
In crisis situations, such as when main communications is damaged or invaders have locked out normal communications systems, some ships have an emergency communications system, which the crew can access. An emergency communications system is half the strength of the main communications system; it uses many of the same resources of the main communications system but on a separate subsystem from the main grid. Some Emergency communications allow for one-way emergency transmissions through a microscopically generated quantum slipstream, preprogrammed to certain places that is assured to receive the message and send help.
Some of the latest Starfleet vessels incorporate a system, which links communications with a small holo-emitter array (sometimes, it can interface with a ship equipped with a holo-grid on every deck). When used to communicate with another, similarly equipped, vessel, a holocommunications system allows the persons communications to ‘see’ each other as if they were right in the room with them.