To ensure that devices in a network are synchronized with each other and also use the correct absolute time, they are connected to a central time reference. This so-called Grandmaster Clock normally receives the absolute world time via GPS. The GPS antenna required for this is connected to the Grandmaster Clock via a coaxial cable. Depending on the length of the cable, this results in signal delays of up to half a µs. This signal delay previously had to be corrected manually. In order to minimize deviations between the GPS time and the time within the network, Omicron Lab has now developed a device that combines the GPS antenna and the actual time reference in a compact, waterproof and weatherproof housing. The antenna-integrated Grandmaster Clock OTMC 100 can be installed in a suitable location and connected directly to the Ethernet. There is no need to lay a coaxial cable between the GPS antenna and the Grandmaster Clock. The device uses either the Network Time Protocol (NTP, SNTP) or, for applications with particularly high accuracy requirements, the Precision Time Protocol (PTP) in accordance with the IEEE 1588-2008 standard. With a diameter of 116 mm and a height of 107 mm, the Grandmaster Clock is particularly suitable for installation in confined spaces and for portable or temporary use.