Beta (time signal)
Beta is a time signal service in the VLF range in Russia, operated by the Russian Navy.[1] There are 6 transmitter stations, which take turns transmitting time signals and other communications.
Although the transmitters are active 24 hours a day, each transmits the time code one hour per day.
Beginning on the hour is 25 minutes of 25.0 kHz, including morse code station identification and time code. This is followed by 5-minute intervals of 25.1, 25.5, 23.0 and 20.5 kHz. No time code is sent during the last quarter of an hour.
The Beta network
Beta consists of the following transmitters: [2]
| Callsign | Transmitter Location | 20.5 kHz | 23 kHz | 25.1 kHz | 25.5 kHz | Map Link |
|---|---|---|---|---|---|---|
| RJH69 | Vileyka VLF transmitter near Molodechno (Belarus) | x | x | x | x | 54°27′44″N 26°46′09″E / 54.462356°N 26.769218°E |
| RJH77 | Archangelsk | x | x | x | x | 64°21′38″N 41°34′07″E / 64.360491°N 41.568489°E |
| RJH63 | Krasnodar | x | x | x | x | 45°24′14″N 38°09′20″E / 45.403904°N 38.155689°E |
| RJH99 | Nizhny Novgorod (former German Goliath transmitter) | x | x | x | x | 56°10′19″N 43°55′54″E / 56.171945°N 43.931667°E |
| RJH66 | Bishkek (Kyrgyzstan) | x | x | x | x | 43°02′22″N 73°36′45″E / 43.039444°N 73.6125°E |
| RAB99 | Khabarovsk | x | x | x | x | 48°29′08″N 134°49′24″E / 48.48555°N 134.82333°E |
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 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:[4]
- 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, 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 | Digital data, ±50 Hz frequency-shift keying, 50 baud[5] | |
| Off | :47 | Transmission ends | |
See also
References
- ↑ C3 Systems of the CIS Navy
- ↑ Marten, Michael (2007). Spezialfrequenzliste 2007/08, band 2 (in German). Siebel Verlag. p. 36. ISBN 978-3-88180-665-7.
- 1 2 The Russian VLF time-signal stations, “Beta”, by Trond Jacobsen, with detailed transmission format information.
- ↑ Meinberg radio clock glossary: R, see entries for RAB99, RJH69, RJH77, RJH86 and RJH90
- ↑ 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..
Further reading
- VLF radio networks information
- The Russian VLF time-signal stations, “Beta”, by Trond Jacobsen, with detailed transmission format information.
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