Military communications or military signals involve all aspects of communications, or conveyance of information, by armed forces. Military communications span from pre-history to the present. The earliest military communications were delivered by humans on foot. Later, communications progressed to visual and audible signals, and then advanced into the electronic age. Examples from Jane’s Military Communications include text, audio, facsimile, tactical ground-based communications, terrestrial microwave, tropospheric scatter, naval, satellite communications systems and equipment, surveillance and signal analysis, encryption and security and direction-finding and jamming.