A Black Box, also known as a Fax Machine or K-series transmitter, is a special type of faster-than-light communications device, operating through the same hyperspace medium used by Jump Drives and hyperpulse generators. Initially discovered by the Star League, it would be rediscovered by Archon Katrina Steiner, her lover Duke Arthur Luvon of Donegal, and Morgan Kell of the Kell Hounds mercenary unit. Black boxes would become a critical means of communication for the Lyran Commonwealth and its allies.
Black Boxes were first proposed to the SLDF Communications Command in 2572 as an alternative to the "Pony Express" system of communications then in use. Developed under the codename Project TRANSIENT, prototype units were delivered in 2580 to the SLDF's Rim Worlds commanders during the Reunification War. The devices were able to pass small amounts of data (~200 kilobytes), usually inputted in a fax-type manner , to other Black Boxes within a hundred light years. The relativly fast speed, compared with the common transmission per JumpShip, and the small size of the messages relegated them only to the most important traffic. But after years of development on a small budget, Project TRANSIENT was terminated in 2614 and following the appearance of the much more capable Hyperpulse Generator in 2630 the SLDF Communications Command ordered all the Black Boxes collected and dismantled, but until then all worlds of the Star League received an exemplar  and at least one device survived into the 31st century.
How Katrina Steiner came to discover this technology is unknown, but when she returned from the Periphery after her one-year disappearance in 3005 she brought back an example. (More recent speculation is that Katrina and her companions stumbled across the device in the remains of the SLDF 17th Royal Division's headquarters on Taran's World. This facility was struck by a dirty bomb and SLDF engineers simply bulldozed the site and buried it in ferrocrete.)
When the Lyrans allied with the Federated Suns to form the Federated Commonwealth in 3020, one of the secrets shared with the Suns was the existence of the black box technology. Working in conjunction with the New Avalon Institute of Science, the Department of Military Communications and Research was born, and in November 3027 demonstrated the use of the black boxes for military communication. Within months the Department was distributing dozens of black boxes to military commands throughout the AFFS and LCAF. Black boxes would prove instrumental in the Fourth Succession War, especially when ComStar instituted a communications blackout within FedCom territory on false pretenses.
However, during the war the Draconis Combine was able to recover several black boxes, and would use them during the War of 3039. While not completely lax in their encryption protocols, neither the Lyrans nor Suns believed that the Combine had access to their technology, and so many of their messages were intercepted and used against them during the war. ComStar also became aware of the black box technology, and stepped up efforts to target members of the Department of Military Communications. Realizing that their enemies had access to their technology, FedCom redoubled their efforts to encrypt their transmissions, though it would not be until 3051 during the Clan Invasion that the Combine formally revealed its own possession of black boxes.
Unlike an HPG, a black box radiates a signal that propagates outward through hyperspace, like ripples in a pond. However, it was believed by Star League scientists that this phenomenon would interfere with the workings of jump drives and HPG transmitters. These black boxes, while only the size of a briefcase and so much more portable, could not compare to HPGs in terms of speed or size of message that could be transmitted, which prompted their initial abandonment.
When rediscovered and adopted by FedCom, all black boxes were fitted with a self-destruct and tracking device. These safeguards were assumed to be enough to prevent their misuse, however the events of the War of 3039 would prove otherwise. Since its adoption, a number of different black box models have produced.
 K-0 Series
 K-1 Series
The first FedCom improved production model from 3027, it was implemented and used during the Fourth Succession War. It increased the speed and range to twenty-five light-years per day and two hundred light-years respectively.
 K-1A Series
 K-1B Series
 K-2 Series
 K-3 Series
 K-3A Series
 K-4 Series
A true revolution in black box technology, the K-4 was introduced in 3048 and increased message speeds to one hundred light-years per day with a range of six hundred light-years. It also increases the size of the data packet that can be sent, allowing for megabytes of data to be transmitted.
 K-5 Series
Introduced in 3054, K-5 black boxes have a range of eight hundred light-years, with a propagation speed of one hundred and fifty light-years per day. It can send up to thirty-five pages of text, and have a capability to handle four channels.
 K-6 Series
Introduced in 3061, K-6 black boxes have a range of one thousand two hundred light-years, with a propagation speed of one hundred and eighty light-years per day. It can send up to fifty pages of text, and have a capability to handle nine channels.
- ↑ 1.0 1.1 ComStar (sourcebook), p. 6
- ↑ 2.0 2.1 2.2 Historical: Reunification War, p. 25
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Historical: War of 3039, p. 68
- ↑ 20 Year Update, p.16
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Handbook: House Davion, p. 181-183