Greenwich Time Signal Greenwich Time Signal The Greenwich Time Signal (GTS), popularly known as the pips, is a series of six short tones broadcast at one-second intervals by many BBC Radio stations. The pips were introduced in 1924 and have been generated by the BBC since 1990 to mark the precise start of each hour. Their utility in calibration is diminishing as digital broadcasting entails time lags. There are six pips (short beeps) in total, which occur on each of the 5 seconds leading up to the hour and on the hour itself. Each pip is a 1 kHz tone (about halfway between
Greenwich Time Signal as from the Droitwich AM transmitter, which is the distance to Central London. As a pre-IRIG and pre-NTP time transfer and transmission system, the pips have been a great technological success. In modern times, however, time can be transferred to systems with CPUs and operating systems by using BCD or some Unix Time variant. Newer digital broadcasting methods have introduced even greater problems for the accuracy of use of the pips. On digital platforms such as DVB, DAB, satellite and the internet, the pips—although "generated" accurately—are not "heard" by the listener exactly on the hour. The encoding and decoding of