The GRM-3000 is a low-cost, GPS and Rubidium custom board-level module available in a variety of sizes and form factors. It uses a powerful GPS receiver and the patented smart SRO-100 SynClock+®, integrating complex disciplining and synchronization functionality all in one low-cost, super-small package. The SRO integrates SmarTiming+® technology, providing a suite of built-in timing features. SmarTiming+ filters and disciplines any type of input reference such as GPS, Cesium, Maser, and E1/T1 auto-adaptively at leading-edge 1ns resolution, while modeling the stability-affecting temperature range of the SRO at 0.1ºC resolution.