Potok is a system made up of Soviet, then Russian, Geizer telecommunications satellites placed in geostationary orbit by Proton launchers. They are responsible for relaying data collected by reconnaissance satellites circulating in low orbit to fixed or mobile ground stations. This system developed by Lavochkin began to be deployed in 1982. The tenth and last satellite was placed in orbit in 2000. The Potok system is being replaced by the Garpoun satellites whose first launch took place in 2011.

The Potok system in nominal configuration consists of four Geizer satellites occupying the longitudes 80° east and 13.5° west with one operational satellite and one backup satellite per position. The Soviet Union had also reserved the 168° west position but it was never used. The Geizer satellite, which has a mass of ~2 300 kg, uses the platform KAUR-4 stabilized 3 axes. This platform has solar panels of 40 m² and uses 4 SPT-70 plasma engines to maintain the satellite on its position. The satellite uses an octagonal shaped phased array antenna that is pointed with an accuracy of 0.1°. The Slav-2 and Sintez transponders, which operate in C-band, are developed by NPO Elas. The receiving stations on Earth, mobile or fixed, use parabolic antennas with a diameter between 2.6 and 3 meters.