Nadezhda (11F643N, 17F118) was a Soviet civilian satellite navigation system used by the Soviet Merchant Marine and Academy of Sciences, but also by the military, as part of the Tsikada constellation. They featured also a COSPAS search and rescue system.
The Nadezhda and Tsikada satellites were very similar to the Parus satellites and also used a NPO PM built pressurized cylindrical bus with gravity-gradient stabilization. The satellites transmitted Doppler-shifted VHF transmissions at around 150 MHz and 400 MHz of their position and orbital characteristics. They operated from a 1000 km orbit with 82.9° inclination. Satellites were placed in planes spaced 45° apart.
The development of Tsikada began in 1974 and the first satellite was launched in 1976. The system entered the operational phase in 1978.
Nine satellites were launched, all on Kosmos-3M boosters. Three received Kosmos designations, the remaning were launched as Nadezhda.
A modified Nadezhda-M was launched as the tenth Nadezhda satellite.
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