Abstract: A system includes a Mobile User Objective System (MUOS) geostationary earth orbit (GEO)-based communication satellites (ComSat) to provide a persistent and on-demand communication links between multiple LEO space vehicles, their associated air and/or ground users and operations centers. The system further includes one or more LEO space vehicles that can communicate with the GEO-based MUOS ComSats using UHF communication links. Each of the LEO space vehicles includes radio circuitry to enable communicating over an ultra-high frequency (UHF) band used by the MUOS GEO communication link in compliance with the MUOS Wideband Code-Division Multiple-Access WCDMA waveform standard or other user defendable waveforms.

Abstract: A dual rate transmitter may include a modulator circuit configured to modulate orthogonal signals to generate a quadrature modulated signal. An amplifier may be configured to amplify the quadrature modulated signal to produce an amplified signal. A quadrature partial response (QPR) filter may be configured to process the amplified signal to generate an output signal. The QPR filter may allow for full rate QPR and half rate QPSK operation of the transmitter device. The output signal may be transmitted via an antenna. This transmitter approach provides a bandwidth efficiency improvement, as the QPR signal may be operated at twice the rate within the same bandwidth as the quadrature modulated signal using a common saturated transmitter implementation, reducing quantity of components and the resulting mass and cost reduction for a space transmitter solution. Additionally, this approach of using QPR signaling provides greater power efficiency.

Abstract: An interface circuit includes a generator for driving an interface signal to a receiver which produces an output signal in response thereto. The generator (or driver) includes a pair of relatively larger complementary conductivity field effect transistors and a pair of relatively smaller complementary conductivity field effect transistors (FETs), each pair in series circuit between the supply rails. The interface signal is produced at a connection of the center points of both pairs of FETs. A control device renders like ones of the FETs in each pair alternately conductive responsive to the input signal, however, the control device generates control signals for the FETs such that the relatively smaller FET of a given conductivity becomes conductive before the larger FET of that same conductivity. The receiver includes a voltage divider to attenuating and coupling the received interface signal to a high-gain amplifier which produces the output signal.