DDS在光泵磁力仪频率锁定中的应用
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摘要
光泵磁力仪测量微弱磁场的实验中,通常需要一个射频场作用于铷原子气室,当发生共振时,所加射频场的频率就等于拉莫尔进动频率,可以通过这个频率换算出待测磁场的值。当待测磁场的值发生变化时,共振频率也会发生变化,因此要求所加的射频场能够追踪共振频率的变化。直接数字频率合成器(DDS)具有频率分辨率高、输出频率稳定和控制方便等优点,因此提出并研制了一种基于DDS的频率锁定系统。DDS用的是AD9854芯片,用微控制器(MCU)读取锁相放大器的输出电压,然后进行比例运算并控制DDS的输出频率,从而达到频率锁定的目的。
In the experiment of measuring weak magnetic field with magnetometer, it is usually necessary to produce a radio frequency(RF) field acting on the rubidium atomic gas chamber. When resonance occurs, the frequency of the applied RF field is equal to the Larmor frequency, and the value of the magnetic field to be measured can be converted by this frequency. When the value of the magnetic field changes, the resonant frequency will also change.So the frequency of the RF field is required to track the change in resonant frequency. The frequency resolution of the direct digital synthesizer(DDS) is high, the output frequency is stable and the control is convenient. A frequency lock system based on DDS is designed and studied in this paper. This DDS is based on IC AD9854. In order to achieve the frequency locking, a micro control unit(MCU) is used to read the output voltage of the lock-in amplifier, then doing the proportional operation, and to control the output frequency of DDS.Thereby the purpose of frequency locking is achieved.
In the experiment of measuring weak magnetic field with magnetometer, it is usually necessary to produce a radio frequency(RF) field acting on the rubidium atomic gas chamber. When resonance occurs, the frequency of the applied RF field is equal to the Larmor frequency, and the value of the magnetic field to be measured can be converted by this frequency. When the value of the magnetic field changes, the resonant frequency will also change.So the frequency of the RF field is required to track the change in resonant frequency. The frequency resolution of the direct digital synthesizer(DDS) is high, the output frequency is stable and the control is convenient. A frequency lock system based on DDS is designed and studied in this paper. This DDS is based on IC AD9854. In order to achieve the frequency locking, a micro control unit(MCU) is used to read the output voltage of the lock-in amplifier, then doing the proportional operation, and to control the output frequency of DDS.Thereby the purpose of frequency locking is achieved.
引文
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[2]肖胜红,肖振坤.弱磁场检测方法与仪器研究[J].舰船电子工程,2006,26(4):160-161.
[3]管志宁.地磁场与磁力勘探[M].北京:地质出版社,2005.
[4]晋芳,杨宇山,郑振宇,等.原子磁力仪研究进展[J].地球物理学进展,2011,26(3):1131-1136.
[5]张昌达.量子磁力仪研究和开发状况[J].物探与化探,2005,29(4):283-287.
[6]姜智鹏,赵伟,曲凯峰.磁场测量技术的发展及其应用[J].电测与仪表,2008,45(4):1-5.
[7]张昌达,董浩斌.量子磁力仪评说[J].工程地球物理学报,2004,1(6):499-507.
[8]肖建华.光泵磁共振原理的图像阐释[J].四川师范大学学报,1996,19(5):103-107.
[9]毛敏,王淑仙,刘锦高.新型直接数字合成式扫描仪的原理和研制[J].仪器仪表学报,2004,25(4):534-537.
[10]于淑萍,张幸儿.基于FPGA/MCU多功能信号发生器的设计与实现[J].电力自动化设备,2009,29(12):106-109.
[11]杨会成.基于FPGA的直接数字频率合成信号发生器的设计[J].安徽工程科技学院学报,2005,20(3):4-6.
[12]罗义军,罗迪,李劲.一种宽带频谱分析结构优化与FPGA实现[J].浙江工业大学学报,2018,46(1):51-55.
[13]孔德鹏,孔德辉,舒露丝.基于FPGA的新型五阶超混沌吸引子的实现[J].浙江工业大学学报,2013,41(3):351-354.
[14]周守利,俞俊学,陈伟,等.低功耗单片低噪声放大器芯片[J].浙江工业大学学报,2016,44(6):624-627.