Design Of Chaotic Frequency Hopping Synthesizer Used In 2.4GHz Bi-Directional Convertion System

With the development of communication technology, more and more researches and applications are used in spread spectrum and secure of communication, and that the requirements are becoming higher. Meantime the chaos theory in communication and circuitry attract widespread attention. The random likeness of chaos phenomenon is very suitable for the security of communication. Besides, the CFH(Chaotic Frequency Hopping) is high sensibility to the initial value, that may generate a lot of frequency-hopping sequences which are irrelevance and random likeness but certain.In this paper we will design a PLL(Phase Locking Loop) frequency synthesizer with CFH, which is applied for the band of 2GHz.We use the MCU to calculate the Logistic-Map, then the control bytes will be sent to the chip of PLL frequency synthesizer for generating CFH sequences. We should scale up properly the both sides of equation of the Logistic-Map to make the MCU could calculate it. It will transfer the clock and controlling signal to the chip which are processed properly by the MCU, according to the requests of the controlling words format and transfer timing. In the chip, different controlling words can synthesize different CFH signals, which is same with the processed Logistic-Map. In the subsequent validation, the system which is made of digital components can meet the requirements of the function and the basic performance indicators. Besides, it has a better anti-jamming compared with analog circuits.The design generated 600 CFH signals which were maintaining in the chaotic state in the testing process. And the noise figure meet the requirements in the center of 2GHz frequency range as well. So the development trend is very good in the field of spread spectrum communication, even the military communications whose demand is more higher.