Abstract: A radio frequency signal direction finding system wherein radio frequency signals received at output ports of a multibeam array antenna are sequentially sampled, in response to a sampling signal, at a frequency f.sub.s. The sampled signals are fed to a receiver channel which is tuned to the sampling frequency to produce a composite signal having a frequency f.sub.s and a phase angle, relative to a reference phase angle of the sampling signal, which provides an indication of the relative signal levels received at the output ports and hence an indication of the angular direction of a source of the radio frequency signals.

Abstract: Apparatus for improving the signal to noise ratio in an electrical signal. A signal enhancement processor operating in real time and selecting signals based upon the similarity of the incoming signal to a locally generated reference and which does not require that signals be filterable in the frequency domain, that external reference signals be supplied, or that signal amplitude criteria be employed. A system for providing input signal attenuation or rejection as a function of the frequency or phase of the input signal, with attenuation at a maximum for an undesired signal and at a minimum for a desired signal.