认知跳频系统调制与数字下变频研究及其FPGA实现

发布时间：2018-06-29 09:08

本文选题：认知跳频通信 + TCM　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：随着社会经济科技的不断发展,无论是民用领域还是军用领域都对通信的有效性和可靠性提出了更高的要求,能否实现高效、高可靠、高安全通信已成为衡量一个通信系统优劣的重要指标。跳频通信由于其优异的抗干扰、抗截获和易组网等能力,使其在军事通信和部分民事通信领域得到广泛的应用。然而,随着通信需求不断上升、信道电磁环境日益复杂多变、干扰技术不断升级,传统跳频通信已无法满足现代通信特别是军事通信的要求。认知跳频通信把认知无线电技术引入跳频通信,通过频谱感技术实时感知信道电磁环境,动态分配频谱,适时改变系统参数,从而实现高效可靠安全的信息传输。认知跳频通信被认为是解决传统跳频困境的有效途径之一。本文对认知跳频通信系统进行研究,介绍了一种实用的认知跳频通信系统设计方案。然后重点对应用于该认知跳频系统中的调制与数字下变频技术进行了研究,并对这两部分进行了FPGA实现。针对本系统对误码性能和频带利用率的特殊要求,本文重点对TCM调制和CPM调制技术进行了研究。TCM调制把纠错编码和调制作为一个整体考虑进行最佳设计,可以有效提升系统的误码性能。CPM调制是一类相位连续的调制方式,相位连续、包络恒定、具有记忆性的特点使其具有频谱利用率高、无非线性效应、误码性能好等优点,非常适合高传输效率、高误码性能要求的场合。然后本文对应用于本系统中的GMSK调制、TCM8PSK调制和8CPFSK调制进行了具体研究,并在FPGA中进行了硬件实现。数字下变频是数字接收机的重要组成部分。本文对数字下变频相关技术进行具体研究,并结合本认知跳频系统信号宽带宽、采样速率高的特点,基于多相滤波理论,设计了一种基于多相结构的多级滤波抽取的数字下变频方案,并最后在FPGA上进行了具体实现,经实际测试,该方案符合系统要求。
[Abstract]:With the continuous development of social economy and science and technology, both civil and military fields have put forward higher requirements for the effectiveness and reliability of communications, whether to achieve high efficiency, high reliability, High security communication has become an important index to measure the merits and demerits of a communication system. Frequency hopping communication (FH) has been widely used in military communications and some civil communications due to its excellent anti-jamming, anti-interception and easy networking capabilities. However, with the increasing demand for communication, the increasingly complex electromagnetic environment and the continuous upgrading of jamming technology, the traditional frequency-hopping communication can no longer meet the requirements of modern communications, especially military communications. The cognitive frequency-hopping communication introduces the cognitive radio technology into the frequency-hopping communication, through the spectrum sense technology real-time perceives the channel electromagnetic environment, dynamically allocates the frequency spectrum, changes the system parameter in time, thus realizes the efficient, reliable and safe information transmission. Cognitive frequency-hopping communication is considered to be one of the effective ways to solve the traditional frequency-hopping dilemma. In this paper, the cognitive frequency-hopping communication system is studied, and a practical design scheme of cognitive frequency-hopping communication system is introduced. Then, the modulation and digital down-conversion techniques applied in the cognitive frequency hopping system are studied, and the FPGA implementation of these two parts is given. According to the special requirements of the system for error performance and frequency band efficiency, this paper focuses on TCM modulation and CPM modulation technology. TCM modulation takes error correction coding and modulation as a whole for optimal design. CPM modulation is a kind of continuous phase modulation, which has the advantages of continuous phase, constant envelope, memory, high spectral efficiency, no nonlinear effect, and good error rate. Very suitable for high transmission efficiency, high error performance requirements. Then the GMSK modulation TCM8PSK modulation and 8CPFSK modulation which are applied in this system are studied and implemented in FPGA. Digital down conversion is an important part of digital receiver. In this paper, the correlation technology of digital down-conversion is studied in detail. Combining with the characteristics of wide bandwidth and high sampling rate of this cognitive frequency-hopping system, based on the theory of polyphase filtering, A digital downconversion scheme based on multilevel filtering and decimation with polyphase structure is designed and implemented on FPGA. The practical test shows that the scheme meets the requirements of the system.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN914.41;TN911.3;TN791

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