The HP / Agilent 53131A Universal Frequency Counter is a compact, high performance unit designed for benchtop and system automation. The 53131A has frequency resolution of 10 digits per second, 500 ps time interval resolution and a complete set of test and analysis features.

The 53131A configuration options include two 225 MHz channels, an optional third channel to 3 GHz, 5 GHz, or 12.4 GHz, and one of three available time bases. Standard measurements include: frequency, frequency ratio, time interval, rise/fall time, phase, duty cycle, positive/negative pulse width, totalize, peak voltage, time interval average and time interval delay.