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Constructing Prototype Lock-in Amplifier with LabVIEW & DAQ. Xiaoyu Wu 08300290011 Dept. of Physics, Fudan University. What is Lock-in Amplifier(LIA)?. Detect & Measure Signals Even with overwhelming noise Typical S/N ratio -60dB. Signal + Noise. Amplitude + Phase as DC. - PowerPoint PPT Presentation
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Constructing Prototype Lock-in Amplifier with LabVIEW & DAQ
Xiaoyu Wu08300290011
Dept. of Physics, Fudan University
What is Lock-in Amplifier(LIA)?
• Detect & Measure Signals• Even with overwhelming noise• Typical S/N ratio -60dB
Signal + Noise
Amplitude + Phase as DC
Typical Application: Scanning Tunneling Spectroscopy
Principle of LIA
• Phase Sensitive Detection• Orthogonality of Sinusoidal Functions
LOW-PASS FILTER
LabVIEW & DAQ
Realizing the Algorithm
Demonstration
Features
• Signal Frequency: ~Hz to ~kHz• Signal Amplitude: 0.005V tested• Sampling Rate: maximum 50kHz, 40kHz tested
Drawbacks
• S/N Ratio• Function Generator
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