Under the 2004 Agreement on the Promotion, Provision, and Use of GALILEO and GPS Satellite-Based Navigation Systems and Related Applications, the member states of the European Union and the United States agreed on working together, intensifying thus the cooperation on interoperability and compatibility issues between GALILEO and GPS. Among other topics, one important focus was the E1/L1 frequency band, centred at 1575.42 MHz, where the GALILEO Open Service (OS) signal and the modernized L1 civil (L1C) signal are going to be transmitted along with many other RNSS signals. The opportunity to design new signals in this preeminent radionavigation frequency band has significant importance to future users worldwide. Recent joint efforts by United States and European experts have identified MBOC (multiplexed BOC) [1][2][3][4][5] as a promising joint solution for E1 OS and L1C, along with multiple sets of spreading waveforms that yield this optimized spectrum. The resulting optimized E1 OS and L1C spreading modulations enable receivers to obtain significantly better performance in multipath than with previously considered spreading modulations, along with other potential benefits. The optimized spreading modulation provides considerable flexibility for receiver designers, and simpler receivers that employ only BOC(1,1)-based processing, experience very modest performance degradation, compared to the baseline BOC(1,1) spreading modulation.