Accurate time references are critical to system performance. However, there are various environmental conditions that can affect oscillator performance. Exposure to electro-magnetic energy is one such example. Electromagnetic susceptibility (EMS) is the susceptibility of a device to electromagnetic radiation from external sources, such as radiation from other components on the printed circuit board. To demonstrate oscillator EMS, various oscillators were tested in an accredited test lab according to IEC 61000-4.3 standards. The devices under test were placed on a non-conductive table 80 cm above the chamber floor with an antenna placed at 3 m from the target device in an anechoic chamber.