The Stanford Research SR620 is an interval timer and frequency counter capable of measuring signals from 0.001 Hz to 1.3 GHz. The device is equipped with a graphical output that can be displayed on an oscilloscope and interchanged between a histogram, strip chart of mean values, and jitter. Up to one million samples are used to automatically calculate mean, standard deviation, Allan variance, or minimums and maximums. The input impedance is configurable to either 1 MΩ or 50Ω and supports AC or DC coupling. In frequency counter mode, the SR620’s input sensitivity is 60 mV from 1 to 40 MHz. CMC’s SR620 is equipped with Option 01, which uses an ovenized VCXO timebase.