Editing Beta (time signal) (section)

== Frequency usage ==
The time code consists of a series of signals on multiple frequencies.  Transmission starts on the hour.  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 transmitters are estimated to operate at 1000&nbsp;kW, achieving 30–50&nbsp;kW [[EIRP]].  (The difference is due to the low efficiency of antennas at this frequency, which must be much smaller than the 12&nbsp;km wavelength.)

{|class="wikitable" style="text-align:center"
|+Beta hourly transmission schedule<ref name="trond">[http://www.vlf.it/russianvlf/russianvlf.htm The Russian VLF time-signal stations, “Beta”], by Trond Jacobsen, with detailed transmission format information.</ref>
!rowspan=2| Frequency ||colspan=2|Minutes ||rowspan=2| Signal
|-
!Start || Duration
|-
|rowspan=7| 25.0 kHz
| :00 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :01 || 5 ||align=left| Unmodulated carrier
|-
| :06 || 1 ||align=left| Morse code call sign, on-off keying
|-
| :07 || 3 ||align=left| Unmodulated carrier
|-
| :10 || 3 ||align=left| On-off modulated with 40 Hz square wave
|-
| :13 || 9 ||align=left| Time code, on-off modulation
|-
| :22 || 3 ||align=left| On-off modulated with 40 Hz square wave
|-
|rowspan=2| 25.1 kHz
| :25 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :26 || 4 ||align=left| Unmodulated carrier
|-
|rowspan=2| 25.5 kHz
| :30 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :31 || 4 ||align=left| Unmodulated carrier
|-
|rowspan=2| 23.0 kHz
| :35 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :36 || 5 ||align=left| Unmodulated carrier
|-
|rowspan=2| 20.5 kHz
| :41 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :42 || 5 ||align=left| Unmodulated carrier
|-
| Off
| :47 || ||align=left| Transmission ends
|}

The time code consists of a series of carrier pulses:<ref name="meinberg">[http://www.meinberg.de/english/glossary/r.htm Meinberg radio clock glossary: R], see entries for [http://www.meinberg.de/english/glossary/rab-99.htm RAB99], [http://www.meinberg.de/english/glossary/rjh-69.htm RJH69], [http://www.meinberg.de/english/glossary/rjh-77.htm RJH77], [http://www.meinberg.de/english/glossary/rjh-86.htm RJH86] and [http://www.meinberg.de/english/glossary/rjh-90.htm RJH90]</ref>
* Each 100 ms, a 25 ms burst of carrier is transmitted
* Each second, a 100 ms burst of carrier is transmitted
* Each 10 s, a 1 s burst of carrier is transmitted
* Each minute, a 10 s burst of carrier is transmitted
The hour or date is not coded.

Most of the stations were built in the 1970s.  RJH63 and RAB99, built later, has a different transmission:

{|class="wikitable" style="text-align:center"
|+RJH63 and RAB99 hourly transmission schedule<ref name="trond"/>
!rowspan=2| Frequency ||colspan=2|Minutes ||rowspan=2| Signal
|-
!Start || Duration
|-
|rowspan=6| 25.0 kHz
| :00 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :01 || 5 ||align=left| Unmodulated carrier
|-
| :06 || 1 ||align=left| Morse code call sign, on-off keying
|-
| :07 || 2 ||align=left| Unmodulated carrier
|-
| :09 || 2 ||align=left| On-off modulated with 40 Hz square wave
|-
| :11 || 9 ||align=left| Time code, on-off modulation
|-
|rowspan=2| 25.1 kHz
| :20 || 2 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :22 || 1 ||align=left| Unmodulated carrier
|-
|rowspan=2| 25.5 kHz
| :23 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :24 || 2 ||align=left| Unmodulated carrier
|-
|rowspan=2| 23.0 kHz
| :26 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :27 || 4 ||align=left| Unmodulated carrier
|-
|rowspan=3| 20.5 kHz
| :31 || 1 ||align=left| Transmitter tune-up, low-power unmodulated carrier
|-
| :32 || 4 ||align=left| Unmodulated carrier
|-
| :36 || 4 ||align=left| (RJH63 only) Digital data, ±50 Hz [[frequency-shift keying]], 50 [[baud]]<ref name="nils">[http://web.me.com/nils.schiffhauer/Website/Monitoring/Eintr%C3%A4ge/2011/7/11_Audio_Clips_-_Medium_Wave_%28%26_Longwave%29.html Nils Schiffhauer's medium/long-wave signa samples].  Particularly see the [http://web.me.com/nils.schiffhauer/Website/Monitoring/Eintr%C3%A4ge/2011/7/11_Audio_Clips_-_Medium_Wave_%28&_Longwave%29_files/RJH86FSK.jpg (frequency-shifted) transmission spectrum.] Horizontal divisions at 200 Hz show 100 Hz between frequencies.</ref>
|-
| Off
| :40 || ||align=left| Transmission ends
|}