The TIP Navy Navigation Satellite and its onboard computer system

The high precision clock, the general purpose mini-computer, the Orbit Adjustment System (OATS) and the Drag Compensation System (DISCOS) components of the new TIP (Transit Improvement Program) satellites of the TRANSIT Navy Navigation Satellite System are described. An important part of the operations performed by the hydrazine-fueled OATS is to select optimum directions for thrusting to correct the altitude and inclination together and minimize the fuel requirements. The main task of the DISCOS is to remove the analog-track component of drag and radiation. The flight computer with 32K words of memory and specialized Input/Output logic is serving various spacecraft functions in real time while the incrementally programmable synthesizer (IPS) is used to maintain a high-precision clock by observing the satellite epoch on the ground and injecting IPS control parameters for clock steerage. The software for the ground support system includes at least five major programs and uses four different computers. The main flight computer software is a set of basic programs called SYS which are resident in memory at all time while other special programs can be loaded by SYS only when needed.