Abstract: A visual display system provides patterns for visually aiding an operator determining the nature and noise environment of the incoming signal. A conventional signal receiver and an oscilloscope are coupled to a phase detector, a clock circuit and a frequency synthesizer. The clock circuit synchronizes the operation of the receiver, phase detector and frequency synthesizer. The phase detector includes a digital delay means for imparting a digital time delay between two signals and has two outputs connected to the X and Y deflection terminals of the oscilloscope screen for effecting a display in a lissajous form and another, third output connected to the Z terminal to vary the intensity of a part of the screen such that patterns are generated on the oscilloscope that might represent the inherent nature of the incoming signal which might include, the type of noise, the presence of doppler shift or CW interference, or drift of a component.