ETAK is a communications device which modulates quantum pulses to communicate with the Shivans. It was developed by Admiral Bosch using data from a defunct GTI (Galactic Terran Intelligence) project involving captured Shivan specimens. The name ETAK is short for Etamnanki, the tower that may have inspired the story of Babel.
During the Battle of Deneb, a GTVA assault force detected several shielded cargo containers, the contents of which are believed to be related to ETAK. Initially suspecting it to be a weapon of mass destruction, they destroyed the cargo units in the area, ostensibly to disrupt Bosch's research. Later, scans were made of the Iceni by deep cover SOC operatives within the Neo-Terran Front, though details of these scans were not immediately made clear.
The Alliance later discovered the true nature of the ETAK project as a communications device after the Iceni was detected sending and receiving signals from a Shivan Rakshasa-class cruiser, the SC Rephaim, in the nebula beyond Gamma Draconis. The Shivans later attacked and boarded the Iceni, killing most of the crew and taking Bosch and several of his crew away with them. The actual Iceni device was destroyed along with the ship itself when Bosch activated the vessel's self-destruct system, but specifications were provided to the GTVA by the few surviving crew members of the rebel command ship after they were extracted. It is unknown what the GTVA intends to do with that data.
There is no significant canonical data on the device itself, its size, power or computing requirements, and range of transmission.
Communications and alliance with the Shivans were to be essential to Bosch's plans for Neo-Terra, and ETAK was to be a central part of that alliance, allowing, for the first time, communications with the Shivans. As a result, ETAK was central to much of the NTF Rebellion and although initial contact was, in Bosch's words, "rudimentary and crude," it served that purpose.
ETAK and Allied Command
There are many details in the main campaign which point to least some elements of GTVA command knowing of and supporting the ETAK project, despite Bosch's extraordinary efforts towards keeping it secret and destroying evidence of its existence. For example, cargo found near Bosch's Boadicea base in Deneb, which Command believed was related to ETAK, was destroyed rather than captured and analyzed. Later, Bosch was allowed to escape the Deneb system when the blockade of the node was removed, and the 53rd Hammerheads were given inaccurate coordinates while attempting to intercept and capture his command ship. Command also passed up several opportunities to destroy the Iceni, despite knowing its location, and even ordered pilots of the Vasudan 203rd squadron not to engage the Iceni when it was discovered in the nebula communicated with the SC Rephaim.
No detail is given as to how the Alliance found out about ETAK. Indeed, it is never even openly admitted in the game, but interrogation of rebel prisoners revealed only that only the most senior members of the rebellion were ever given details of the ETAK project, suggesting that the Alliance had a source in the rebellion close to Bosch himself.