Abstract: A design method for a satellite navigation signal system with mixed modulation of direct spread spectrum and frequency hopping includes: modulating the spread spectrum code sequence of multipath signal components; mixing and multiplexing with the signal components corresponding to the same frequency point; forming a baseband code sequence; separating signal components corresponding to the baseband code sequence to obtain separated radio frequency signals; recombining and modulating separated radio frequency signals; controlling the frequency hopping pattern by the frequency hopping code sequence if the separated radio frequency signals are authorized signals, and performing mixed frequency synthesis modulation; performing direct combined radio frequency modulation if the separated radio frequency signals are unauthorized signals, and obtaining the recombined signal component; amplifying the signal power to obtain the direct spread spectrum navigation signal.

Abstract: A Beidou short message communication method and a system for a low-power user terminal are provided.

Abstract: A massive multiple-input multiple-output channel emulation method and a device based on optical matrix switching are provided. The method is realized based on a massive multiple-input multiple-output channel emulation system, which includes a plurality of channel preprocessing subsystems, an optical switching subsystem, a plurality of channel characteristic emulation subsystems, a self-checking and self-correcting subsystem, a mathematical simulation and monitoring subsystem and a time-frequency synthesis and distribution subsystem. All the subsystems are interconnected by various optical fiber connections, which are used to transmit high-speed data signals, communication information, control instructions, frequency, pulse and time signals, and have the centralized-distributed layout ability of various devices in the system based on long-distance transmission of optical fiber signals, and have the massive parallel expansion ability of the number of system signal input and output links.

Abstract: A massive multiple-input multiple-output channel emulation method and a device based on optical matrix switching are provided. The method is realized based on a massive multiple-input multiple-output channel emulation system, which includes a plurality of channel preprocessing subsystems, an optical switching subsystem, a plurality of channel characteristic emulation subsystems, a self-checking and self-correcting subsystem, a mathematical simulation and monitoring subsystem and a time-frequency synthesis and distribution subsystem. All the subsystems are interconnected by various optical fiber connections, which are used to transmit high-speed data signals, communication information, control instructions, frequency, pulse and time signals, and have the centralized-distributed layout ability of various devices in the system based on long-distance transmission of optical fiber signals, and have the massive parallel expansion ability of the number of system signal input and output links.