Made circa 1985 by Navstar Systems, the ‘Navstar A-300S’ is a satellite navigation receiver that worked with the Transit satellite system to determine a user’s position and speed.

The Transit satellite system was developed by the United States Navy during the Cold War to provide accurate location information to Polaris ballistic missile submarines. Transit satellite system became operational in 1964 and the technology was later made available to civilians and the commercial market. By the 1980s, navigators working on thousands of warships, freighters and private watercraft used the Transit system. This was partly due to changes in how consumer electronics were manufactured and advances in chip technology.

The Navstar A-300S was developed by a satellite navigation research and development team based in Daventry, UK. This receiver demonstrates how satellite receivers began to be produced on a smaller size and at a lower cost. It is about two-thirds of the size of a Walker Transit receiver model (see ZBA9312) built in 1981.