Ross Brannan is an ELINT analyst.
That term refers to Electronic Intelligence, defined by the NSA as " information derived primarily from electronic signals that do not contain speech or text". For those wanting to surround themself with even more acronyms, it is divided into three basic 'branches': TechELINT (studying radars, beacons, jammers, and navigational signals), OpELINT (determining what capabilities any particular nation or organization possesses), and TELINT (intel derived from the intercept, processing and analysis of foreign telemetry).
Brannan knows this stuff extremely well. He was well trained in it by the U.S. Army Security Agency and is just about to wrap up his stint in that armed forces organization specializing in ELINT when we meet him for the first time. While there is no doubt he is happy with his expertise and capabilities in the field, he is less than thrilled with the couple months of his time still remaining and hoping for approval of his early-out request. He had some vacation time in Europe planned before heading to a new gig in Arizona working in ELINT but as a much better paid civilian. The year of this introduction is 1973 and the pay for enlisted was not very good (still isn't, IMHO).
That vacation will have to wait, though, as he is picked for a particularly harrowing one-last-assignment which will turn an analyst used to being a ways back from the action to someone having to do his intercept work while dodging bullets and evading enemy capture, which is all definitely not what he was hoping.
That experience will set the path for his new career, part of an elite group of intelligence collectors working as a joint task force named Raven One. "The Raven One mission, initiated by the Secretary of Defense, bypassed the lower levels of authority, and was approved in a matter of days by the president's national security advisor. Experts from the DoD, such as Brannan, would work with operatives from both NSA and CIA to get as close to the action as they can to gain the information needed back in Washington.