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基于DDS的2PSK调制_通信工程专业论文范文

发布时间:2015-01-24 来源:人大经济论坛
通信工程专业论文 以下为一级目录,详细目录及内容请与本站联系 目 录 引言………………………………………………………………………………1 1 绪论……………………………………………………………………………1 2 设计要求……………………………………………………………………7 3 使用的器件及芯片介绍…………………………………………………8 4 方案设计……………………………………………………………………17 5 电路实现……………………………………………………………………19 6 电路制作和调试心得体会………………………………………………20 7 结论……………………………………………………………………………21 谢辞………………………………………………………………………………23 参考文献…………………………………………………………………………24 附录………………………………………………………………………………25 摘 要 二进制移相键控方式是受键控的载波相位按基带脉冲而改变的一种数字调制方式。由于二进制移相键控系统在抗噪声性能及信道通信频带利用率等方面比二进制FSK及OOK的优越,因而被广泛应用于数字通信中。本课题就是采用了最流行的DDS技术来实现2PSK调制的。 DDS技术中,输出信号波形的三个参数;频率、相位和振幅A都可以用数据字来定义。的分辨率有相位累加器中比特数来确定,的分辨率由ROM中的比特数确定,而A的分辨率由DAC中的分辨率确定。因此,在DDS中可以完成数字调制和模拟调制。频率调制可以用改变频率控制字来实现,相位调制可以用改变瞬时相位来实现。本课题采用的芯片AD9856就是基于直接数字频率合成技术,在单片机的控制下实现信号的2PSK调制。该芯片功能强大,具有多种调制功能,只需要使用外部控制器写入对应的控制字,就能够实现信号的2PSK调制。基带信号可以由单片机产生的串行码元控制DDS发生器的相位控制端来实现,而AD9856芯片内部集成的锁相环可以产生载波,其频率也是通过外部单片机的接口来设置。 关键字:直接数字频率合成;2PSK调制;相位累加器;控制字;基带信号;载波频率 Abstract 2PSK modulate way to modulate the way signal carrier a kind of figure that phase place changes according to pulse of the baseband that key Control.. Because it is more superior than that of the binary scale FSK and OOK that the binary scale moves the looks key and accuses of the system in resisting noise performance and channel communication frequency band utilization ratio etc., widely used in digital communication. This subject is to adopt most popular DDS technology to realize 2PSK and modulate. In DDS technology, output three parameters of the signal wave form ; Frequency , phase place and amplitude A can all be defined with the data word. There are the resolution ratio of frequencies bit is counted to confirm in accumulating device of phase place , the resolution ratio of the phase place is counts and confirms by bit in ROM, and the resolution ratio of amplitude A is confirmed by the resolution ratio in DAC. So, can finish figures to modulate and modulate with simulation in DDS. Modulating and can control words to realize with the frequency of changing in frequency, the phase place is modulated and can be realized by changing the instantaneous phase place. Chip AD9856 that this subject adopts is because of the directly digital frequency synthetic technology, realize under the control of the one-chip computer that 2PSK of the signal is modulated. This chip is powerful, have many kinds of modulation function , only need to use the outside controller to be written into the corresponding control word, can realize that 2PSK of the signal is modulated . Baseband signal can control by serial each that one-chip computer produce phase place , DDS of generator control and bring in realizing, and the phase locking ring of the integration can produce the signal carrier within AD9856 chip, its frequency is set up through the interface of the outside one-chip computer. Key words: Digital frequency is synthetized directly; 2PSK is modulated; the accumulating device of phase place, control words; the signal of the baseband; the frequency of the signal carrier
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