GMSK is employed in fielded commercial cellular systems such as GSM and military satellite communications systems such as A-EHF SATCOM. Closely related SOQPSK and Multi-h CPM is used in UHF SATCOM and Advanced Range Telemetry (ARTM) systems. LDPC codes are used in or proposed for several commercial and DoD systems. The robust and high performance, high data rate, methods developed in this effort would offer greater capabilities and size, weight, and power reduction for each of these communications systems. Future space missions at near Earth, lunar, and deep space distances that require spectral efficient communications will benefit greatly from the robustness and size, weight, and power reduction offered by the proposed GMSK and LDPC technology. Future small satellites and other miniature platforms would be able to use much more efficient power amplifiers with the given techniques, and high data rate applications such as high definition video could be more reliably supported in limited assigned frequency bands.