The Globalstar system breakthroughs in efficiency in microwave and signal processing technology

The Globalstar system will employ active phased array antennas and energy management in combination with CDMA technology to achieve unprecedented power efficiency for satellite communications. Active phased array antennas incorporate multibeam functionality in very small space. Such phased array antennas depend upon the use of highly efficient and uniform MMIC amplifiers that were not previously available. MMIC amplifiers coupled directly to each radiating element result in very high G/T and EIRP for the size of the antenna apertures and power capacity and noise figures of the amplifiers. As a result, unprecedented dc to RF power efficiency is achieved in the transmit direction and from input flux density to C/N in the receive phased arrays. The Qualcomm CDMA waveform employed in the User Terminals (handsets) and Gateways to the terrestrial networks (PSTNs), spreads the RF energy evenly over the allotted spectrum, as seen by the user antennas, optimizing power handling (signal fidelity) in the MMIC amplifiers. This CDMA implementation originally developed for terrestrial cellular and PCS works particularly well in a system that employs a constellation of low earth orbiting (LEO) satellites.