Beta (time signal)
Template:Short description Beta is a time signal service in the VLF range in Russia, operated by the Russian Navy.<ref name="c3systems">C3 Systems of the CIS Navy Template:Webarchive</ref> It is controlled by All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology.<ref name="vniiftri">Template:Cite FTP. Official signal specification.</ref> There are 6 transmitter stations, which take turns transmitting time signals and other communications.
Each transmitter has 1 or 2 scheduled sessions per day lasting 31–41 minutes, depending on transmitter, total 8 sessions in 24 hours. Beginning on the hour is 15–20 minutes of 25.0 kHz, including morse code station identification and time code. 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. No time code is sent during the last quarter of an hour.<ref name="vniiftri"/>
The Beta networkEdit
Beta consists of the following transmitters:<ref>Template:Cite book</ref><ref name="vniiftri"/>
| Callsign | Transmitter Location | 20.5 kHz | 23.0 kHz | 25.0 kHz | 25.1 kHz | 25.5 kHz | Coordinates |
|---|---|---|---|---|---|---|---|
| RJH63 | Krasnodar | x | x | x | x | x | Template:Coord |
| RJH69 | Vileyka VLF transmitter near Molodechno (Belarus) | x | x | x | x | x | Template:Coord |
| RJH77 | Archangelsk | x | x | x | x | x | Template:Coord |
| RJH86<ref>in air RJH66</ref> | Bishkek (Kyrgyzstan) | x | x | x | x | x | Template:Coord |
| RJH90 | Nizhny Novgorod (former German Goliath transmitter) | x | x | x | x | x | Template:Coord |
| RAB99 | Khabarovsk | x | x | x | x | x | Template:Coord |
Frequency usageEdit
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 kW, achieving 30–50 kW EIRP. (The difference is due to the low efficiency of antennas at this frequency, which must be much smaller than the 12 km wavelength.)
| Frequency | Minutes | Signal | |
|---|---|---|---|
| Start | Duration | ||
| 25.0 kHz | :00 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :01 | 5 | Unmodulated carrier | |
| :06 | 1 | Morse code call sign, on-off keying | |
| :07 | 3 | Unmodulated carrier | |
| :10 | 3 | On-off modulated with 40 Hz square wave | |
| :13 | 9 | Time code, on-off modulation | |
| :22 | 3 | On-off modulated with 40 Hz square wave | |
| 25.1 kHz | :25 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :26 | 4 | Unmodulated carrier | |
| 25.5 kHz | :30 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :31 | 4 | Unmodulated carrier | |
| 23.0 kHz | :35 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :36 | 5 | Unmodulated carrier | |
| 20.5 kHz | :41 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :42 | 5 | Unmodulated carrier | |
| Off | :47 | Transmission ends | |
The time code consists of a series of carrier pulses:<ref name="meinberg">Meinberg radio clock glossary: R, see entries for RAB99, RJH69, RJH77, RJH86 and 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:
| Frequency | Minutes | Signal | |
|---|---|---|---|
| Start | Duration | ||
| 25.0 kHz | :00 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :01 | 5 | Unmodulated carrier | |
| :06 | 1 | Morse code call sign, on-off keying | |
| :07 | 2 | Unmodulated carrier | |
| :09 | 2 | On-off modulated with 40 Hz square wave | |
| :11 | 9 | Time code, on-off modulation | |
| 25.1 kHz | :20 | 2 | Transmitter tune-up, low-power unmodulated carrier |
| :22 | 1 | Unmodulated carrier | |
| 25.5 kHz | :23 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :24 | 2 | Unmodulated carrier | |
| 23.0 kHz | :26 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :27 | 4 | Unmodulated carrier | |
| 20.5 kHz | :31 | 1 | Transmitter tune-up, low-power unmodulated carrier |
| :32 | 4 | Unmodulated carrier | |
| :36 | 4 | (RJH63 only) Digital data, ±50 Hz frequency-shift keying, 50 baud<ref name="nils">Nils Schiffhauer's medium/long-wave signa samples. Particularly see the (frequency-shifted) transmission spectrum. Horizontal divisions at 200 Hz show 100 Hz between frequencies.</ref> | |
| Off | :40 | Transmission ends | |
See alsoEdit
ReferencesEdit
Further readingEdit
- VLF radio networks information
- The Russian VLF time-signal stations, “Beta”, by Trond Jacobsen, with detailed transmission format information.
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