Software emulated multichannel lock-in detector

Abstract
A computer program and simple hardware are described for performing multiple channel phase sensitive detection (and synchronous signal averaging) in the low audio frequency range using a laboratory minicomputer. Additional techniques are described to provide a real‐time display of the harmonic content of a signal and a method of calibrating the frequency dependent phase shift of a filter network. The application of these techniques to precise measurements of the wave form of the de Haas‐van Alphen oscillations are discussed.