As early as 1967, Canadian researchers had been involved in trials with the U.S. on the use of UHF satellites for mobile services primarily for defence operations. The use of UHF frequencies, with satellites such as LES-5, LES-6 and TACSAT offered the possibility of small lightweight mobile or transportable terminals, and several demonstrations were carried out in the land, maritime, and aeronautical environment. The world's first direct aircraft-to-aircraft voice communications via satellite was carried out May16, 1970 between two Canadian DND aircraft.
"Historical Development: MSAT Program,"
Online Journal of Space Communication: Vol. 2
, Article 8.
Available at: https://ohioopen.library.ohio.edu/spacejournal/vol2/iss4/8
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