Made in 1985 by Navstar Systems, the ‘Navstar 602S’ is a satellite navigation receiver that worked with the Transit satellite system to determine a user’s latitude and longitude. The Navstar 602S was manufactured for marine markets including fishing and commercial.
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.

This unit did not replace Decca, the prevailing electronic system of navigation based on receiving fixed radio transmissions. Rather, the 602S was most often used by marine navigators in conjunction with Decca and other existing navigational systems including dead reckoning devices (compasses and log). It is an example of satellite navigational technology in transition and used in conjunction with the more established Decca system. There were three variants of the 600 series, 601S, 602S and 603S, each with progressive improvements in terms of features and cost reduction. In the 1990s, the Transit system was made obsolete by the Global Positioning System (GPS) and ceased service in 1996.