The 3575A compares the amplitude and phase of two input signals and displays them on a 3.5-digit LED display on the front panel. The base model instrument has one digital panel meter in the left position, while options add a second one in the right position. A front panel switch selects presentation of the amplitude or phase on the single-display version, while the dual-display version can display amplitude and phase simultaneously.

The instrument has a phase display resolution of 0.1 degrees, and an amplitude display resolution of 0.1dB. The display update rate is 4Hz.

Analog voltages representing the relative amplitude and phase are available on rear-panel BNC connectors. These are useful for connection to external measurement devices such as digital voltmeters which may have significantly higher resolution than the 3575A's internal 3.5-digit panel meter(s). This is also useful for long-term data logging applications, such as comparing the stability of an oscillator to a reference signal.