Hyper Pulse Generator
The HyperPulse Generator (HPG) arrays are based on numerous worlds all across the Inner Sphere. ComStar owns and operates these, collecting payment from those who wish to transmit messages. The FTL devices are the primary means of interstellar communications, and ComStar has a virtual monopoly on their usage.
A HyperPulse Generator (HPG) is a variant of KF Jump Drive technology based on an obscure speculation by Thomas Kearny and Takayoshi Fuchida that it might be possible to create artificial jump points. This proved correct, but the energy costs were such that it was not possible to send a ship through. Instead, the effect was harnessed to transmit electromagnetic signals - communications.
Each HyperPulse Generator is essentially a small physics unit (with mobile units being as small as nine tons) which is able to fire a "pulse" through hyperspace to a receiving HPG. Because the HPG's messages are not burdened by tens or hundreds of thousands of tons of mass, the maximum range of an HPG pulse is 50 light years, while a ship can jump a maximum of 30 light years.
Each pulse can carry terabytes of compressed information, everything from simple text to books and video. One millisecond of transmission time, just enough for two pages of bare text or a small image, is equal to one C-Bill, with larger items taking longer and thus having a higher cost. On average the time for transmission of a non-priority message between Terra and Tharkad takes about a week, and from Terra to the limits of the explored Periphery about six months. Priority message over the same distance could take between few hours to a day depending on conditions and network message load.
The Star League and ComStar HPG network is based on a simple two-stage system of primary or Class A HPGs (the Prime or First Circuit), and a secondary network of Class B hyperpulse relay stations (the Outer Circuit) determined upon the size the world's position, population and importance, with the over 50 or so Class A stations the network's main hubs and the Class B stations located on virtually every inhabited world. While processed serially, as transmission are expensive, messages are frequently bundled into batches of hundreds to be sent simultaneously. While the First Circuit consists entirely of Class A stations and transmits roughly every six hours, after the fall of the Star League it may be days or weeks before a message is sent from the Class B stations of the Outer Circuit , though one can pay a higher fee in order to send a message sooner.    
Messages sent via ComStar and the Word of Blake are charged on per-transmission basis, dependent on how many stations the message must traverse to reach its destination. For example a 1 millisecond message worth 1 C-Bill that must travel via 15 stations would have a final cost of 15 C-Bills. Priority messages however are almost prohibitively expensive, an identical 1 millisecond message sent on a priority basis would be in the range of a 1,000 C-bills per station, with the station of origin also asking for an upfront 5,000 C-Bill for interrupting the normal message schedule. 
The side effects of an HPG include substantial EMP that can temporarily disable battlefield targets. However, an HPG is designed to carefully target objects moving in predictable patterns many light-years distant (i.e., HPGs on other planets) and is thus essentially unable to "attack" battlefield targets. 
- Standard Planetary HPGs - The most common and familiar version in known space, the planetary HPG consists of a gigantic antenna dish surrounded by an installation that includes fortified EMP damping architecture, independent power supplies and large facilities for staff and operators. While stations of the original Star League were integrated into the communities they served, their vulnerability to attack during the Amaris Coup resulted in ComStar developing separate heavily protected compounds. These massive structures are virtual mini-fortresses designed as much to defend ComStar personnel from outside attack as to separate them from the influences of the general populace.
- A typical compound has a facade that is aesthetically pleasing, partially to conceal the extent of their fortification. Usually it is surrounded by a ferrocrete wall that incorporates Star League-era surveillance equipment, supported in some cases by concealed minefields. A fusion reactor provides power independent of the local grid, with both it and the HPG housing encased in blast-proof material, and the entire facility can be sealed against the environment. Medical facilities, including surgical theaters, are present in many compounds. Food, water and other supplies kept within storage facilities and elaborate underground tunnel networks - many large enough to accommodate BattleMechs - can allow the staff to remain cut-off from the outside world for up to a year and a half. Escape tunnels also allow ComStar personnel to secretly enter and exit the facility as needed, with at least one connecting to the local ROM safe house. 
- Mobile HPGs - As well as the standard planetary station, the Terran Hegemony were also successful in miniaturizing the technology to develop Mobile Hyperpulse Generators. The most common form of mobile HPG is the 50 ton model installed upon large spacecraft such as JumpShips and WarShips introduced in 2655, though an even smaller 12 ton ground-mobile model designed for transport by ground vehicles or BattleMechs was developed in 2751. While relied upon heavily by the SLDF and the civil services of the Hegemony, in the modern era only the Clans and both halves of the sundered ComStar have access to the mobile systems, jealously guarding the technology even after the Schism.  
- Enhanced Range Secure HPGs - The Enhanced Range Secure HPG was developed by the scientists of the WCDC during the early 3030s, with the design having grown from first principles of KF Field Theory over several years. As such, the design of the ERS-HPG is vastly different to that of a Standard HPG. Not only is it somewhat more compact than a Standart HPG, but also has a boosted range of up to 75 ly.
- The Secure part of the ERS-HPG describes the decision to increase the security of the HPG by utilizing the Ansible Packet Protocol APP developed for the Caldran Ansible and a Quantum Encryption module. This utilizes robust quantum technology to encrypt the HPG signal for transmission. This is largely to defeat the problem of HPG radio backscatter and prevents a third party from listening in.
HPG Radio Backscatter
HPG Radio Backscatter was discovered in the mid to late 3020s by WCDC Survey Personnel, during the first surveys into Inner Sphere space, in this case the Circinus Federation. It utilizes the fact that all incoming and outgoing radio messages through the artificial Jump Point leak past the jump point and can be detected by conventional, if sensitive radio equipment. This allowed the WCDC to listen in to Comstar HPG network traffic and even decrypt all protocols and secret messages sent over the network, with the exception of one-time-pad encrypted messages.
- BattleTech - 25 Years of Art and Fiction, p. 8 "HPG communications"
- MechWarrior, 2nd Edition, p. 152 - "Hyperpulse Generator"
- ComStar, p .6 "Linking the Stars"
- BattleTech Compendium: The Rules of Warfare, p. 111 "Wolfnet Archive File: 32211-BF5-11/7/23"
- Null Set, p. 45 "Hyperpulse Technology - Hyperpulse Generator"
- Explorer Corps, p. 92 "New Equipment - Hyperpulse Generators"
- ComStar, p. 26 "ComStar Compounds"
- Tactical Operations, p. 330 "Mobile Hyperpulse Generators"