Crosslink Hyper Speed Multimode Modem (CHM3)

The exponential growth in information technology has led to a commensurate explosion in data transfer requirements. Satellite transmission presents a unique set of challenges since the links need to satisfy this burgeoning demand 10 years after launch. The new satellite generation must maintain compatibility with the preceding constellation in order to maintain coverage and crosslink interconnectivity. Transponder power consumption limitations preclude the high order QAM modulations that have become prevalent for terrestrial modems. Satellite transponder power amplifiers achieve their highest efficiency when they are driven into compression, requiring a modulation that is essentially constant envelop, yet fits within a narrow channel. The Crosslink Hyper Speed Multimode Modem (CHM3) sets the course to obtaining data rates of 10Gbps while satisfying the unique bandwidth and power constraints of satellite links. Crosslinks with existing on orbit satellites are maintained by selecting an architecture that shifts modulation formats on-the-fly, enabling a graceful transition to the next generation communications package. Channel latency is dramatically diminished by incorporating block phase estimation to accelerate acquisition when switching between modes. The Phase I effort includes a thorough evaluation of the proposed techniques and culminates in an ASIC specification for a fully compliant 50Mbps modem.