On orbit programmable frequency generation system for JCSAT 9 spacecraft

Abstract

The JCSAT 9 communications satellite, developed by Lockheed Martin Commercial Space Systems using an A2100 spacecraft, will use an on-orbit configurable frequency generation unit (FGU) that is SEU hard and total dose tolerant. The spacecraft is due for launch in 2005. The FGU design illustrates the principles and benefits of a single loop synthesizer generating low noise and multiple local oscillators for various frequency (up/down) converters in the payload. Nineteen phase-locked loops are configured to provide coherent, multiple, and redundant C and L band local oscillator frequencies by combining digital, analog and microwave concepts to achieve small size, low mass, low DC power consumption, low phase noise, and spectral purity. The requirement for coherent signal processing is achieved by synthesizing all local oscillator signals from a highly stable reference frequency source. The FGU contains a dedicated control card, which provides the capability to address each frequency synthesizer, and also to program each synthesizer to its required frequency. The control card is designed to receive commands via a bi-directional serial bus using the satellite on board computer. The FGU is powered from the spacecraft bus with dedicated redundant electronic power conditioners (EPC). The design requirements of small size, low mass and low power consumption, were met by a unique design concept that is modular and easy to test.