General information about Anthorn MSF

The Anthorn Transmitting Station is located near Anthorn, Cumbria, England and is operated by VT Communications. The Station has two transmitters: one VLF (Very low frequency) and one LF (Low Frequency - 60 kHz).

The MSF transmission from Anthorn is used to spread the UK national standards of time and frequency which are maintained by the National Physical Laboratory. The signal provides adequate field strength throughout the UK and it can be received widely in northern and western Europe. A simple on-off modulation of the carrier frequency (60kHz) is used to transmit BCD-coded informations about time and date. Every UTC second is marked by an off stage of carrier of at least 100ms. This second marker has an accuracy better than +/- 1ms.

The time code format is a one minute time frame, which is used to transmit data applied to the following minute. To broadcast the informations, bits 'A' and 'B' of each second are used (see code format below). If the carrier is on a logical '0' is transmitted, otherwise a logical '1'.The first second of a minute nominally contains a period of 500ms with carrier off to serve as a minute marker. However, there may be on/off carrier modulation between 25ms and 330ms during second 00 to distribute information of hour, minute, day and month with a fast 100 bits/s code. Seconds 01B to 16B are used to transmit the difference between UTC and UT1 (which is closely equivalent to GMT), called DUT1. Seconds 17A to 51A are used to transmit the local time and date. Seconds 52A to 59A include informations about change of BST/UTC, BST status and some parity bits.