The Design And Implementation Of GPS Jammer

Global Positioning System(GPS) satellite navigation system is a kind of typical Code Division Multiple Access(CDMA) spread spectrum broadcasting system. Based on the profound study of the contents and formats of satellite navigation messages, pseudo random coding system and its Binary Phase Shift Keying(BPSK) modulation mode,according to the basic principle of signal jamming, this dissertation puts forth a kind of jammer implementation scheme for the satellite navigation system to carry out blanket jamming and deception jamming.The GPS jammer put forth by this dissertation synthesizes the required jamming signals with Direct Digital frequency Synthesizer(DDS) as the nucleus. Under the blanket jamming mode, pseudo random sequence is generated by Central Processing Unit(CPU),and BPSK jamming signals corresponding with GPS satellite navigation signal parameters are generated by control DDS chips, which will produce blanket jamming after amplified in power and radiated externally; under the deception jamming mode, the current navigation messages are received by the GPS receiving module in the jammer, after uncertainly delayed or relevant navigation messages are falsified, the navigation messages of some satellite transmitted from the receiving module is synthesized to be signals that accord with the authentic satellite navigation signals by CPU and these synthesized signals are then radiated externally, and consequently the deception jamming comes into being.The GPS jammer designed by this dissertation is centered with DDS, the synthesis method of signal is simple and feasible, which can not only realize blanketing jamming,but also realizing deception jamming, and the jamming output power can be adjusted. In the meantime, this jammer can be equipped with eight channels of output at most, under blanket jamming mode, these eight channels can work in different frequency bands, which can realize other forms of jammings. Through appropriate adjustment of softwares and hardwares, these eight channels of this jammer may realize a no-gap coverage with the frequency of 0-2.4GHz.During the research process of this jammer, scheme design, chip model selection,layout design, as well as Printed Circuit Board(PCB) design and processing has been completed, and on this base, the programming and debugging of all modular circuits have been carried out. Currently, the blanket jamming signals’ synthesis has been realized, andafter tested, the effective suppressing range is around 200 meters when the output power is0 dBm. As a result of time and software, the deception jamming is still under debugging.