Since 1972, systematic analysis of Cosmos satellites, having near-circular orbits and periods close to 105 min, has revealed that several groups have had the necessary orbital plane spacing to give the global coverage suitable for satellite navigation systems. Replacements have been launched at regular intervals. The current systems comprise three satellites with 60 degrees spacing, six with 30 degrees spacing and three with 45 degrees spacing. These satellites have been shown to transmit on frequencies close to 150 and 400 MHz. The modulation of the 150 MHz carrier frequencies is explained together with the techniques employed to decode Standard Moscow Time, the satellite's position in geocentric Cartesian coordinates with corresponding rates of change at 3 min intervals, plus the orbital parameters of all satellites forming the system.