The combadge is a combination of a badge and communicator, worn by Starfleet personnel on their uniforms during the 24th century. Variations of this form of device have been used on uniforms of other cultures at similar levels of technology also.
Combadges are used for onboard ship communication with other Starfleet personnel, when using the internal communication system is not possible or impractical, for accessing the onboard computer when not in an area where the computer is listening, for ship-to-shore communications and for direct communication to another combadge. Transporters use the combadge to lock-on to its bearer to make transport faster. Combadges are fitted to act as a universal translator.
Due to the size of the combadge, its working range is limited to 500 km, although a starship can boost the signal to bridge larger distances. For maintenance purposes, the combadge can be opened.
Personal Communicator The current Starfleet-issue communicator represents the latest improvement in small subspace radio devices. Its primary role is to maintain voice contact among crew members aboard ship and during away missions and to provide a lock-on contact for transporter operations. Voice contact with other devices, such as the ship's main computers, is also within the communicator's capabilities.
The communicator casing is micro-milled duranium overlaid with gold and silver alloys in a diffusion-bonding process. The metal alloys serve to compliment the aesthetic design of the device, which has been fashioned to resemble the Starfleet emblem.
Subspace Transceiver Assembly The heart of the internal electronics is the Subspace Transceiver Assembly (STA). This circuit incorporates an analog-to-digital voice encoder and low-power subspace field emitter. It is also the same circuit used in devices such as the PADD and the tricorder and shares the efficient data transmission protocols.
Voice inputs are received by a mono-film pickup diffusion-bonded to the inner casing and routed to the STA. While the standard STA possesses input channels for other data, these are not active in the communicator. As all Starfleet communications are normally encrypted, the voice signal pulses are converted by a series of encryption algorithms. These algorithms are changed on a random schedule by Starfleet Command for galaxy-wide subspace transmissions and individual starship codes may be substituted during local away missions.
Battery power is provided by a sarium krellide crystal rated for two weeks in normal use. When close to depletion, the crystal will produce a faintly audible oscillation; it can be returned to full power by induction recharging.
Communicator Control Control of the personal communicator while aboard a Starfleet vessel is a matter of preference and habit. To initiate a voice call, it is simply a matter of tapping the front of the badge to confirm to the STA that the message is meant to go out. This may seem redundant, as the intra-ship comm system is constantly monitoring and routing voice transmissions, but it is a good practice to learn. During away team missions, the tap is essential to conserve internal battery power. The tap activates a dermal sensor to relay a power up command to the STA.
The range of the communicator is severely limited, mainly due to the small size of the STA emitter and power supply. In transmissions between two stand-alone communicators, clear voice signals will propagate only 500 kilometers, this is a tiny fraction of the 40,000 kilometers required to contact an orbiting starship, so it is the starship that must become the active partner in order to receive the communicator's low power signals and transmit corresponding to the communicator's receiver.
User ID Security For security purposes, the communicator is a personalized Starfleet device that can be programmed to respond to the individual crew member's bioelectrical field and temperature profiles using the built in dermal sensor. If an attempt is made to operate an appropriately programmed device by another crew member without security override authority, the communicator will fail to activate. During benign situations, security codes are changed every five days. During emergency situations or when away team members are involved in operations, codes are changed on a random schedule at least once every twenty-four hours.
Secondary Functions Every time a communicator is activated, it conducts a health check upon the assigned crewmember. This check is very basic in nature and consists mainly of vital signs and voice stress analysis. Should any anomaly be detected, the duty medical officer is alerted by the ship's computer.
The commbadge is configured to act as a universal translator but only while in range of shipboard computer systems or an available tricorder system.
If the casing of the commbadge is ever cracked, an emergency distress signal will be emitted.
As a symbol of membership to Starfleet, personnel that have resigned or have been relieved of duty must turn in their commbadge. The act of taking of one's combadge is symbolically representative of taking of one's uniform.