The use of homodyne detection for measuring small frequency differences between two RF oscillators

In this paper we present an experimental set-up for measuring small frequency differences between two RF oscillators [1] by using a homodyne detection scheme [2]. To emulate the oscillators, we used two RF sources whose output signals were mixed and then the low frequency components at the mixer's output was measured with a network frequency analyzer. The purpose of these experiments was to evaluate a possible method to discriminate the resonance frequency change of a TF-BAR sensor as a response to its contamination with certain substances.