The aim of this paper is to introduce a simple technique to analyze the operation of the basic logic gates-based beat frequency detector (BFD). We show that all of the basic logic gates, including AND-gate, NAND-gate, XOR-gate, XNOR-gate, OR-gate, and NOR-gate, can be used as a mixer to implement the BFD. This BFD is simple, easy to assemble, and can be used in control, instrument and measurement systems.
