Foreign instrumentation signals intelligence

Foreign instrumentation signals intelligence (FISINT) is a sub-category of ELINT, monitoring primarily non-human communication. Foreign instrumentation signals include (but not limited to) telemetry (TELINT), tracking systems, and video data links. TELINT is an important part of national means of technical verification for arms control.

Consider a missile test, and how a single source of instrumentation may not be informative. Tracking cameras and radar know the real-time position and speed, and, of course, if there is a catastrophic event, the cameras may be the only clue.

While the video and radar imagery know the speed, they do not tell engineers why that speed is reached. It is internal telemetry that will tell them the thrust being produced by the engine, the fuel pump flow rates, fuel and oxidizer in the tanks, electrical power use, the performance of the guidance system, the engine temperature and aerodynamic stresses on the body. Telemetry often includes information on the immediate environment, such as atmospheric pressure, and temperature, which can affect performance.

If the missile is testing warheads and atmospheric reentry, telemetry will give the information on how the missile times and positions the release, but it is other FISINT that tracks the actual release, as well as passive sensors of the other side, such as electro-optical MASINT and radar that follows the warheads. Communications intelligence may provide supplemental information from the conversations of the test crews.

National means of technical verification combine FISINT with measurement and signature intelligence to predict missile performance, including such things as accuracy and throw-weight.