煤矿井下环境恶劣，巷道内超前探测过程中电磁、噪声干扰复杂，超前探测过程中待测的有 效信号微弱，很难准确检测，为实现对微弱激电信号幅值和相位的准确检测，利用双锁相放大技术 实现被测信号从噪声信号中的提取，基于信号试验测试和搭建的矿用聚焦双频激电仪试验平台研 究不同噪音信号干扰下系统的噪声抑制特性。 建立了双锁相放大技术的数学模型，并证明该技术 可用于激电信号检测;理论分析了系统对偶数倍频噪声和奇数倍频噪声的抑制作用，当噪声信号频 率是参考信号频率奇数倍时，待测信号幅值、相位的相对误差均随噪声信号与待测信号幅值比值增 大而增大。 噪声信号频率是参考信号频率偶数倍时，待测信号幅值、相位的相对误差与噪声信号的 幅值、频率、相位无关。 基于上述理论分析，建立了基于双锁相放大技术的测试系统，给出了硬件电 路设计和数字部分处理算法;完成了对测试系统的积分时间特性和噪声抑制特性测试。 结果表明， 积分时间为待测信号周期的整数倍时，直流噪声和偶数倍频噪声对系统基本无影响，交流噪声影响 计算幅值，而对于计算相位影响可忽略。 设计了基于锁相放大技术的原理样机，测试证明激电电压 幅值测量误差绝对值与激电电压信号幅值大小无关，而与频率有关，且该样机可对幅值小于 5 V 的 激电电压信号进行采集，最大测量误差绝对值小于 1.5%，可实现对激电电压信号幅值与相位的高 精度检测。

The underground environment of coal mines is harsh，the electromagnetic and noise interference in the ad⁃ vanced detection process in mine roadway is complicated，and the effective signal to be measured is weak and diffi⁃ cult to be accurately detected. To accurately detect the amplitude and phase of the weak IP signal，the double phase⁃ locked amplification technology is used to extract the signal under test from the noise signal. Based on the signal experiment test and the construction of the mine⁃focused dual⁃frequency instrument test platform，the noise suppres⁃ sion characteristics of the system under the interference of different noise signals are studied. The mathematical model of the dual phase⁃locked amplification technology has been established，and it is proved that the technology can be used for signal detection. The system’s suppression of even⁃numbered frequency⁃multiplied noise and odd⁃numbered frequency⁃multiplied noise have been theoretically analyzed. When the noise signal frequency is an odd multiple of the reference signal frequency，the relative error of the signal amplitude and phase increases with the increase of the ratio of the noise signal amplitude to the waiting signal amplitude. When the noise signal frequency is an even multiple of the reference signal frequency，the relative error of the signal amplitude and phase is independent of the noise signal amplitude，frequency and phase. Based on the above theoretical analysis，the test system is established based on the dual phase lock⁃in amplification technology，and the hardware circuit design and digital part processing algo⁃ rithm are provided. Also，the integration time characteristic and noise suppression characteristic test of the test system are completed. The results show that when the integration time is an integer multiple of the period of the signal to be measured， the DC noise and even⁃numbered frequency noise have basically no effect on the system， and the AC noise affects the calculated amplitude，while the effect on the calculated phase can be ignored. A prototype based on the phase⁃locked amplification technology is designed，and the test proves that the absolute value of measurement error of the voltage amplitude has nothing to do with the amplitude of the voltage signal，but has something to do with frequency. The prototype can collect the voltage signal with amplitude less than 5 V，and the absolute value of the maximum measurement error is less than 1.5%，which can realize the high⁃precision detection of the voltage signal amplitude and phase.