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.
作者
童建平
杨建武
TONG Jianping;YANG Jianwu(College of Science,Zhejiang University of Technology,Hangzhou 310023,China)
出处
《浙江工业大学学报》
CAS
北大核心
2019年第4期448-452,468,共6页
Journal of Zhejiang University of Technology
关键词
直接数字频率合成器
微控制器
光泵磁力仪
锁相放大器
direct digital synthesizer
micro control unit
optical pump magnetometer
lock-in amplifier
