Jŏngjŏm FSO

Jŏngjŏm (Menghean: 정점 / 頂點, "Peak" or "Zenith") is a type of free-space optical (FSO) communication system used by the Menghean Navy and exported to some of Menghe's allies. It consists of four FSO send-receive units which can wirelessly exchange data using visible or, in later versions, infrared light. Compared with a radio frequency system, the Jŏngjŏm FSO is almost impossible to jam or intercept, making it a secure way of transmitting data while operating under highly restrictive EMCON conditions. However, it is limited to line-of-sight transmission and suffers severe attenuation from rain, clouds, and heavy fog.

Background

As far back as the 1930s, the Menghean Navy (then the Imperial Menghean Navy) placed a heavy emphasis on fighting under conditions of radio silence, as radio transmissions could be intercepted and read by enemy forces. Even if transmissions were encrypted, the very presence of an encrypted radio signal could inform hostile forces about the bearing to a Menghean ship or fleet. Menghean forces conducted a number of successful surprise attacks early in the Pan-Septentrion War by approaching under strict radio silence, and during the later years of the Menghean War of Liberation, Communist forces used captured torpedo boats and light vessels to raid coastal bases.

During this early period, Menghean naval ships relied on signal flags and semaphore flags for daytime communication and signal lamps for nighttime communication. As late as the 1990s, many Menghean warships, such as the Ansa-class frigates, included at least one signal lamp on a high platform to maximize signaling range over the horizon.

Though safe against radio interception, these systems had a very low data transfer rate, as they required crews to transmit sinmun components one at a time. The Menghean Navy Code of Signals includes a set of two- and three-flag combinations to use as shorthand for common messages, but allows little flexibility beyond this, and is only visible in daytime. All of these systems also relied on a human observer to identify, write down, and decode signals, making errors and misreadings common. And while impossible to intercept at long ranges, they could all be read (and potentially decoded) if used within visual range of an enemy installation.

Beginning in the early 2000s, Menghe began investigating free-space optical communication as an alternative means of transmitting data. Many Menghean private-sector tech companies, including the large Samsan Group, had been pursuing FSO technology as a means of securely transmitting large volumes of data at college campuses, linking remote mountain villages to the national internet network, or quickly re-establishing communications after a natural disaster. In 2003, the Ministry of National Defense (Menghe) concluded a contract with Samsan Defense to develop an FSO system for the Menghean Navy's warships and shore installations, with development work accelerating after relations with Maverica, Innominada, and the Entente Cordiale broke down in 2005.

The Jŏngjŏm FSO system first entered service in 2011, aboard the Yechŏn-class frigate HO-332 Dŏkju. From that year onward, it was installed on nearly all new-build warships above missile boat size, and retrofitted to many existing warships such as the Chŏndong-class destroyers during mid-life refits or minor maintenance periods. It has also been exported to many Namhae Front navies.

Later expansions

Jŏngjŏm-2

A successor system introduced in 2017, it features a slightly taller transmit-receive unit with both visual and infrared lasers. This gives the platform the option of The visual send-receive units are compatible with the initial version of Jŏngjŏm, but the infrared ones can only communicate with other Jŏngjŏm-2 units.

Jŏngjŏm-W

Jŏngjŏm-W (with W denoting wisŏng or satellite) is an FSO system capable of transmitting data between a surface ship and a satellite. Compared with Jŏngjŏm, it is larger and heavier, usually with only one or two mountings for a shipborne installation. It is typically reserved for large ships serving as formation leaders. It is much less flexible than a conventional SATCOM dome, as it suffers severe attenuation in foggy or overcast conditions, but on a clear day or night it can communicate more securely and more effectively.

Jŏngjŏm-J

Jŏngjŏm-J (with J denoting jamsuham or submarine) is a system used on some Menghean submarine classes. It consists of a single FSO send-receive unit on top of a periscope mast, which can be extended while the submarine is surfaced or at periscope depth. It is less widely used than the surface ship systems, as it takes up the footprint of a full periscope mast and requires another ship or aircraft to be near the submarine.

Dungan

Dungan ("obtuse angle") is a communications pod for aircraft which consists of a Jŏngjŏm-compatible send-receive unit and its associated computing systems. It can be mounted on any Menghean hardpoint with 250mm-spaced bomb suspension lugs, even without a connection to the aircraft's own electronics, and can be fitted to helicopters, fixed-wing aircraft, and UAVs. With two such systems fitted, any helicopter, plane, or UAV can relay signals from one ship to another, extending the FSO link beyond either ship's visual horizon. Because of atmospheric attenuation, however, these relay systems are still limited in their effective range, depending on weather conditions.

See also

• MChGJ-0800 (similar Menghean Army system using SHF radio waves)
• Menghean Navy Code of Signals