宽带频率捷变和复杂调制信号发生器的设计
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摘要
介绍了一种宽带频率捷变和复杂调制信号发生器的设计方法,采用大容量现场可编程逻辑阵列控制高速直接数字频率合成器,产生宽带捷变中频信号,还可进行数字化调频,调相和调幅。以前产生宽带数字调制信号,需要采用宽带正交调制器,由于其群时延频响和温度漂移,精确控制两路中频信号相位正交极其困难。重点介绍采用两路直接数字频率合成器,并进行同步处理和实时相差控制,产生两路相位正交的捷变中频信号,分别与两路正交的数字基带信号分量调制,实现捷变中频信号的数字调制。在捷变中频信号的基础上,利用宽带微波合成本振和直接变频技术,实现整个频率范围的覆盖。实验表明,信号发生器能产生300 MHz的捷变带宽,频率转换时间小于1μs,频率范围250 kHz～3 000 MHz,误差矢量幅度指标小于2%且受温度影响小,可实现多种模拟调制,数字调制,复杂脉冲调制,脉内调制和快速跳频,减小了系统的复杂度和体积,降低了成本。
The design and principle of a complex modulation and wideband agile signal generator is introduced. Through high-capacity FPGA control high speed direct digital frequency synthesizer chip,To generate wideband agile IF signal,Digital FM,PM,AM is also available.Previously produced wideband digital modulation signals, It needs to use wideband quadrature modulator.Because of group delay frequency response and temperature drift of wideband analog quadrature modulator,It's extremely difficult for precise control of two IF signal phase orthogonality.Emphasis is placed on two direct digital frequency synthesizers,and synchronous processing and real-time phase difference control,To produce two agile IF signal with phase orthogonality,They are respective modulated with two quadrature digital baseband signal component,To achieve digital modulation of wideband agile IF signal.On the basis of agile IF signal,Use of the wideband microwave synthesis of local oscillator and direct-conversion technology achieve coverage of the whole frequency range.Experiments show that agility bandwidth of the signal generator is 300 MHz,Frequency switching time less than 1 μs,Frequency range is 250 kHz～3 000 MHz,EVM less than 2% and less affected by temperature,It achieves the various analog modulation,digital modulation,complex pulse modulation,intrapulse modulation and fast frequency hopping, it reduces the complexity,the volume and the cost of the system.
The design and principle of a complex modulation and wideband agile signal generator is introduced. Through high-capacity FPGA control high speed direct digital frequency synthesizer chip,To generate wideband agile IF signal,Digital FM,PM,AM is also available.Previously produced wideband digital modulation signals, It needs to use wideband quadrature modulator.Because of group delay frequency response and temperature drift of wideband analog quadrature modulator,It's extremely difficult for precise control of two IF signal phase orthogonality.Emphasis is placed on two direct digital frequency synthesizers,and synchronous processing and real-time phase difference control,To produce two agile IF signal with phase orthogonality,They are respective modulated with two quadrature digital baseband signal component,To achieve digital modulation of wideband agile IF signal.On the basis of agile IF signal,Use of the wideband microwave synthesis of local oscillator and direct-conversion technology achieve coverage of the whole frequency range.Experiments show that agility bandwidth of the signal generator is 300 MHz,Frequency switching time less than 1 μs,Frequency range is 250 kHz～3 000 MHz,EVM less than 2% and less affected by temperature,It achieves the various analog modulation,digital modulation,complex pulse modulation,intrapulse modulation and fast frequency hopping, it reduces the complexity,the volume and the cost of the system.
引文
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[2] 朱健.多功能射频/微波捷变信号发生器的设计[J].电子质量,2008(5):1-4.
[3] 张克舟,陆洪涛,施敏良.基于AD9910的宽带捷变频频率合成器设计[J].国外电子测量技术,2011,30(8):73-76.
[4] 张克舟,李玉龙,杜江波.DDS捷变频信号发生器中的FPGA控制电路设计[J].电子测量技术,2011,34(11):70-73.
[5] 张晓峰,张朋浩,侯永彬.宽带正交调制器设计与实现[J].无线电工程,2015,45(10):71-73.
[6] 卢炳,马向峰,曹旭东.双路相参脉间随机捷变频频综的设计与仿真[J].电子测量技术,2011, 34(2):10-13.
[7] 周研,刘祖深.基于双DDS跳变的捷变频率发生器的设计[J].电子测量与仪器学报,2010,24(6):590-594.
[8] 刘林,田进军,刘朝辉.基于DDS和直接频率合成技术的超宽带捷变频源设计与实现[J].兵工学报,2010,31(12):1648-1652.
[9] 杨杰,杨光,蒋国琼,等.基于DDS的低杂散捷变频合成器设计[J].信息与电子工程,2011,9(4):422-425.
[10] 顾军.频率捷变信号源的捷变合成研究及实现[J].电子测量技术,2010,33(6):17-19,26.
[11] 李立功,年夫顺.现代电子测试技术[M].北京:国防工业出版社,2008.
[12] 左振平,李立功.数字通信测量仪器[M].北京:人民邮电出版社,2007.