Ground Platforms
It can be difficult to draw the line between a ground-based SIGINT receiving station, and facilities that have control, coordination, and processing functions in the "bigger picture" of signals intelligence. Many stations, for the countries with stations in many parts of the world, do have both aspects. There are also some that are clearly intercept only.
The first signals intelligence platforms were listening stations on the ground. Early tactical stations were in use as early as World War I, but permanent strategic signals intelligence stations were established as world tensions grew before WWII.
Arguably, one combined intercept and jamming technique of WWI was the use of shotguns against carrier pigeons, followed by reading the message attached to the bird.
While pigeons can probably be safe, other collection techniques may enjoy a resurgence. One specialized technique, originally used in the First World War but again in the Korean War, was interception using ground return from wired telephones. In mountainous terrain, it might again have applications, such as Afghan caves where wire might be run without the danger of free-space interception.
Satellite communications generally must be intercepted by large parabolic antennas on the ground, although there are possibilities that aircraft, intelligence satellites, and ships might also intercept. "To receive satellite signals, ...only parabolic antennas are used. If the parabolic antennas are standing on an open site, it is possible to calculate on the basis of their position, their elevation and their compass (azimuth) angle which satellite is being received. This is possible, for example, in Morwenstow (UK), Yakima (USA) or Sugar Grove (USA).".
Read more about this topic: Signals Intelligence Operational Platforms By Nation
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