The Atlantic Hydrographic System (codename System 6, originally Project 844) is a secret hydrophone surveillance network and covert federal system spanning the Commonwealth. It is used to track naval vessels, submarines and commercial ships across most of the Atlantic Ocean for strategic, military and industrial purposes. Operated by the Signals Establishment, the system comprises over 400 hydrophone arrays positioned from Helvasia to Sude, with data processed centrally to track ocean objects in real time.
Project 844 began in 2048 as a joint initiative of the LSRE’s National Marine Establishment in Habacoa and the DSRE’s Defence Surveillance Laboratories, and was largely an extension of earlier scientific oceanographic monitoring. It was trialled in Costa Verde until 2052, where it proved that the Mid-Atlantic Ridge caught and channelled sounds that were able to be picked up as far as 1,000km away. It was expanded in 2055 across a number of new sites, and received the designation System 6 in 2057.
Physically, System 6 comprises small units that have an array of 12-20 hydrophones distributed across the sea floor, usually at depths between 800 and 1,200 metres. The hydrophones convert acoustic pressure waves into signals that are boosted and transmitted to land for processing, where their strength can indicate the relative distance and size of the noisy object. The characteristics of the detected sound can be compared against a large library that helps determine if a source is nuclear-powered, or propelled in a certain fashion. Nuclear submarines are, usefully, particularly distinctive due to their reactor cooling systems and so System 6 has tremendous value in identifying them. Because it exploits the geography of the Mid-Atlantic Ridge, it is most accurate along its edges and tapers off from there.
The network has good insight into the shipping lanes connecting Europe, Africa and the Americas, and tracks activity there for use as economic intelligence and trade leverage. It provides a tremendous, though sensitive advantage in these areas and so it considered a system of high secrecy. Its true purpose is obscured by its colocation and connection to the Commonwealth’s extensive scientific oceanographic infrastructure.