Howtosignalprocessing
- What is sensitivity lock?
- What is the purpose of lock-in amplifier?
- How does lock-in detection work?
- What is phase sensitive detection?
What is sensitivity lock?
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 is the purpose of lock-in amplifier?
Lock-in amplifiers are used to detect and measure very small AC signalsall the way down to a few nanovolts. Accurate measurements may be made even when the small signal is obscured by noise sources many thousands of times larger.
How does lock-in detection work?
They employ a homodyne detection scheme and low-pass filtering to measure a signal's amplitude and phase relative to a periodic reference. A lock-in measurement extracts signals in a defined frequency band around the reference frequency, efficiently rejecting all other frequency components.
What is phase sensitive detection?
Phase-sensitive detection is an important experimental technique that allows signals to be extracted from noisy data. Commercial lock-in amplifiers, often used for phase-sensitive detection, are expensive and host a bewildering array of controls that may intimidate a novice user.
