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Lock-in amplifier - Wikipedia

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A lock-in amplifier is a type of amplifier that can extract a signal with a known carrier wave from an extremely noisy environment. Depending on the dynamic reserve of the instrument, signals up to a million times smaller than noise components, potentially fairly close by in frequency, can still be reliably detected. It is essentially a homodyne detector followed by low-pass filter that is often adjustable in cut-off frequency and filter order. The device is often used to measure phase shift, even when the signals are large, have a high signal-to-noise ratio and do not need further improvement. Recovering signals at low signal-to-noise ratios requires a strong, clean reference signal with the same frequency as the received signal. This is not the case in many experiments, so the instrument can recover signals buried in the noise only in a limited set of circumstances. The lock-in amplifier is commonly believed to have been invented by Princeton University physicist Robert H. Dicke who

Lock-in amplifier - Wikipedia Jump to content From Wikipedia, the free encyclopedia Type of amplifier that emphasizes a specific frequency in a noisy signal This article includes a list of general references , but it lacks sufficient corresponding inline citations . Please help to improve this article by introducing more precise citations. ( June 2012 ) ( Learn how and when to remove this message ) A lock in amplifier uses a multiplier and a low pass filter to compare a reference signal against a noisy signal A lock-in amplifier is a type of amplifier that can extract a signal with a known car

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