Time & Frequency


The Time & Frequency Laboratory establishes, maintains and disseminates the national time scale of Singapore, which is the Coordinated Universal Time of Singapore, UTC (SG) and Singapore Standard Time (SST). NMC aligns SST to the international time scale, the UTC, through regular time comparisons by Global Positioning System (GPS) All-In-View technique under a global network of about forty national time standard laboratories.

National Time Scale of Singapore

NMC currently maintains an ensemble of one hydrogen maser and some caesium atomic clocks. They are regularly compared with other atomic clocks in a global network of time transfers via Global Positioning System (GPS) Common-View. Time data are continuously sent to the BIPM, which in turn computes the International Atomic Time (TAI) and Coordinated Universal Time (UTC) based on contributed data of some 400 atomic clocks from the world.

The national time scale realised by NMC, designated as UTC(SG), was set up in 1997. It is the local realisation of UTC in Singapore. Through regular steering of the frequency, the UTC(SG) is aligned to UTC within 20 nanoseconds at all time. The Singapore Standard Time (SST) is generated by advancing the UTC(SG) by 8 hours to account for the time zone. The SST is therefore aligned to the international time scales.

Industry users and the public can access the national time scale via NMC's time and frequency services in calibration and computer time synchronization.

Traceability of UTC (SG)

Time Dissemination

To obtain time-of-day information, several channels are available for users to access the SST.

Network Time Service (NeTS)
This service enables computer and network users to synchronise their computer clocks to time standard maintained at National Metrology Centre (NMC) (adjusted to the users' time zone) via the Internet. Through NeTS, users will receive time code in one of the following Internet timing protocols: Time protocol, Daytime protocol or Network Time Protocols (NTP). If choosing NTP which is the most commonly used, users can synchronise their machine time with a typical accuracy between 1-50 milliseconds depending on the network traffic and quality of the network service.

Automated Computer Time Service (ACTS)
A free dial-up service that enables computer users to receive time code via an analogue modem and telephone line. Dial-up software on different operating systems is also freely available at the SST website. Through the ACTS time code, users can easily and automatically align their computer time to SST with time transmission accuracy better than 500 milliseconds for Windows, and 100 milliseconds for DOS system.