Frequency Hopping Gmsk Communications And Anti-jamming Frequency-hopping Communications

The content can be divided into two parts: the first one describes the method for implementing GMSK modem under FH condition, and the second one gives a solution which put the DSSS anti-jamming mechanism into FH system. In the first part, firstly, the modulation of GMSK signal is introduced. Secondly, the demodulation of GMSK signal in FH application is presented. The receiver must complete two tasks to demodulate the signal: synchronization of all parameters (estimation and track) and decision. In the explanation of synchronization algorithm, a thorough inspection is given to the timing track loop. The design method of loop filter is a new breakthrough, and it is one of the emphases in this paper.In the second part, we discuss the problem encountered while transferring DSSS signal in FH system, and finally a "FH + long error-correcting code" communication solution based on BPSK modulation is presented. The solution can greatly upgrade the anti-jamming (especially white noise) ability of FH system. According to the ratio of noise power to signal power, the length of code can be selected to guarantee the normal communication.