A modulation for global navigation satellite systems (GNSS) signals called quadrature multiplexed BOC (QMBOC), with the corresponding correlation receiver and constant envelope multiplexing schemes, is presented. Placing the narrowband BOC component and the wideband BOC component in phase quadrature, QMBOC modulation remains an MBOC spectral constraint, which eliminates the cross-term in the autocorrelation function. It provides a new modulation option for interoperable GNSS signals.