Howtosignalprocessing
Lock-in amplifiers use a technique known as phase sensitive detection to single out the component of the signal at a specific frequency and phase. Once it does this, noise signals at other frequencies or random phases are rejected through electronic (analog lock- in) or software (DSP lock-in) filtering.
- What is lock-in technique?
- What is the purpose for dual phase lock-in amplifier?
- How does a phase sensitive detector work?
- What are the advantages of phase sensitive detection of noise?
What is lock-in technique?
The lock-in technique is an AC modulation technique used to detect small AC signals hidden in a noisy environment. Multiplication of the measurement signal by the reference signal results in a DC component proportional to the amplitude of the measured signal at the modulation frequency.
What is the purpose for dual phase lock-in amplifier?
A complete digital dual-phase lock-in amplifier system based on DSP and LabVIEW was designed. It can extract the weak sinusoidal signals submerged by noise. This design has the advantages of high accuracy, low cost and portability, and its update and transplantation are easy.
How does a phase sensitive detector work?
A lock-in, or phase-sensitive, amplifier is simply a fancy AC voltmeter. Along with the input, one supplies it with a periodic reference signal. The amplifier then responds only to the portion of the input signal that occurs at the reference frequency with a fixed phase relationship.
What are the advantages of phase sensitive detection of noise?
Phase sensitive detection enables extremely narrow bandwidth detection (0.001Hz is normal). Typical application scenario is using electric transducers where the amplitude of noise is in mili volts and the signal falls into nano volt region.
