Beta is a time signal service in the VLF range in Russia, operated by the Russian Navy.
[1] It is controlled by All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology.
This is followed by 3- or 4-minute intervals of 25.1, 25.5, 23.0 and 20.5 kHz of unmodulated carrier precisely phase-locked to UTC(SU) time scale.
Each time a new frequency is selected, there is 1 minute of low power while the transmitter is adjusted, then full-power transmissions begin.
(The difference is due to the low efficiency of antennas at this frequency, which must be much smaller than the 12 km wavelength.)