An-li TAO(陶安利), Guo-dong XU(徐国栋), Ke-xue LUO(骆科学), Gang-ling ZHANG(张钢领)
Shandong University of Science and Technology, College of Information and Electrical Engineering, Qingdao 266510, China
Abstract-A method of implementing high cost-effective and hi ghly integrated digital lock-in amplifier with microcontroller is discussed. An d the digital lock-in amplifier is more suitable for measuring low-frequency w eak signal.Digital signal sequence is obtained through sampling signal measured o ver an integer number of signal periods, but digital reference sequence is acqui red through mathematical operation, then digital phase sensitive detection can b e implemented by calculating the cross-correlation function of digital signal s equence and digital reference sequence.In addition, the frequency response and phase character of the digital lock-in amplifier is analyzed. Finally, the desi gned digital lock-in amplifier is achieved. Experimental results show that the digital lock-in amplifier can be used for measuring weak signal with low ignal -to-noise ratio.
Key words-digital lock-in amplifier; SNR; microcontroller
Manuscript Number: 1674-8042(2010)03-0285-04
dio: 10.3969/j.issn.1674-8042.2010.03.18
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