Instruction Manual Four (4) Channel Heterodyne Unit,

This publication contains a general description of, and installation and operating instructions for the Four 4 Channel Heterodyne Unit designed and constructed at Naval Undersea Warfare Center, San Diego, California. The Four 4 Channel Heterodyne Unit is a solid-state instrument, each channel of which accepts an analog input in the audio range, and, by performing time-multiplication against a square wave, shifts the amplitude and phase characteristics of the input to a different set of center frequencies. The new center frequencies are determined by the signals original center frequency and the fundamental and odd harmonic frequencies of the square wave. From this spectrum, the desired band can be isolated by the appropriate filtering.