Correlation detection of fluorescent lamp flicker using a sound card Available to Purchase

In many scientific and industrial fields, including experimental physics, the correlated-detection method is an important technique for detecting weak signals in the presence of a noisy background. By making a correlation calculation, a desired signal can be enhanced while the background noise is suppressed. Due to its importance, correlated-detection has been introduced in physics curricula at many colleges and even in some high schools; however, it is not simple to demonstrate such an important technique in the classroom. Generally speaking, a weak signal source, preamplifier, phase-locked amplifier, correlator¹ (digital or analog), and an oscilloscope are required, which consequently increase the cost and difficulty of a classroom demonstration. Here we describe a simple and low-cost classroom demonstration apparatus for correlated detection of weak flickering signals from a fluorescent lamp. This apparatus allows us to demonstrate the principle of correlation detection using a photodiode, a standard sound-card, and a desktop or...