Bandwidth Efficient Baseband Multi-Modulator

The High Rate Baseband Multi-Modulator (HRBM) ASIC is being developed to provide High-Speed Bandwidth Efficient Modulations to NASA missions. Bandwidth efficiencies from 2.0 bits/symbol/Hz to 2.75 bits/symbol/Hz are selectable from three CCSDS modulations: Gaussian Minimum Shift Keying (GMSK), Filter Offset Quadrature Phase Shift Keying (Filtered-OQSK) and 8-Phase Shift Keying Trellis Coded Modulation (8-PSK TCM). An FPGA version of the HRBM is developed first to verify the individual modulation designs and characterize timing and performance issues involved with digital baseband modulation synthesis. A Finite Input Response (FIR) filter is included to provided baseband pulse shaping to reduce out-of-band spectral emissions. This is filter is programmable and can be tailored to meet system requirements. The ASIC is targeted to provide up to 600 Mbps throughput and will provide serial as well as parallel input. This paper provides an overview of the technology development and current status.