Research Of Low Frequency Hopping Communication System

Because of related characteristics of strong ability to resist interference and low signal to noise ratio, the spread spectrum communication has the superiority of be richly endowed by nature in mine. In underground communication, waves to ground penetration, as fre-quency decreased, about30W power30MHz(narrow band signals) for300m,15MHz for800m,5MHz for1300m. Therefore, low frequency spread spectrum communication tech-nology’prospect is very attractive. As an important type of spread spectrum communication system, frequency hopping communications, with its excellent anti-jamming, anti-fading ability and high security performance, talent showing itself in the spread spectrum tech-nology. The content of this article is a frequency hopping spread spectrum system that is to send the information from the underground through the land by using low frequency radio, and receive corresponding information that send in the underground on the ground.Firstly this article describes the basic principles of spread spectrum communication, its structure and characteristics, and then introduces the basic structure and concept of fre-quency hopping communication system, analysis the principle of communication, introduce the key technology and technical index of frequency hopping communication.Secondly, the article analysis the anti-jamming performance of frequency hopping system, and the uses Matlab software Simulink module to design a computer simulation detection module, detects anti-jamming performance of frequency hopping communication system, analysis its BER in the narrow band single frequency interference and wide band noise interference, and gives the simulation results, so its useful for the design of frequency hopping communication system.Finally, the article focus on the analysis of synchronization process. In the first, in-troduce the two capture method principles and make a improvement on the basic of a cap-ture method which a capture method, the conclusion proves that the improved method largely reduces the capture time of synchronization and reduces the leakage capture rate comparing with the original method, but greatly reduces the complexity of circuit struct with the addition of a capture method comparison of capture time a less obvious increase, finally according to simulation of synchronous system by using Matlab, the results achieves the desired results.