RWM
Encyclopedia
RWM is the callsign of a high frequency
(shortwave) standard frequency and time signal
radio station in Moscow, Russia. RWM transmits on 4996 kHz with 5 kW and on 9996 and 14996 kHz with 8 kW.
The frequencies are very close to those of WWV, and WWVH
. Because of this, RWM is very difficult to receive in North America, due to interference from these said stations.
The mode of transmission is N0N
and A1A
(CW). Between 0 and 8 minutes past the hour, RWM transmits a straight unmodulated carrier wave
. At 9 minutes past, RWM identifies itself in Morse code
. Between 10 and 20 minutes past the hour, RWM transmits a pulse of carrier every second, with the difference between UT1
and UTC in units of one-fiftieth of a second encoded onto the once-per-second pulses. Between 20 and 30 minutes past the hour, RWM transmits 10 carrier pulses each second. This transmission cycle is repeated every half hour.
RWM does not transmit the time of day, only standard time intervals.
The 1 Hz pulses begin on the second, and are doubled (a second pulse transmitted from 200–300 ms past the second) to encode DUT1 and dUT1. Using these values, UT1 may be computed as:
DUT1 may vary between −8 and +8. The number of double pulses sent during seconds 1–8 of each minute encode positive values; if DUT1 = +5, then pulses 1 through 5 will be doubled. Doubling pulses 9–16 encodes negative values similarly.
dUT1 varies from −4 to +4. Positive values are encoded by double pulses during seconds 21–24 of each minute. Negative values are encoded during seconds 31–34.
The 10 Hz pulses are widened in a pattern similar to that of the Beta time signal
: Most pulses are 20 ms, but ones sent on the second are 40 ms, and ones sent on the minute are 500 ms.
High frequency
High frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...
(shortwave) standard frequency and time signal
Time signal
A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.-Audible and visible time signals:...
radio station in Moscow, Russia. RWM transmits on 4996 kHz with 5 kW and on 9996 and 14996 kHz with 8 kW.
The frequencies are very close to those of WWV, and WWVH
WWVH
WWVH is the callsign of the U.S. National Institute of Standards and Technology's shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii....
. Because of this, RWM is very difficult to receive in North America, due to interference from these said stations.
The mode of transmission is N0N
Types of radio emissions
The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier...
and A1A
Types of radio emissions
The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier...
(CW). Between 0 and 8 minutes past the hour, RWM transmits a straight unmodulated carrier wave
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
. At 9 minutes past, RWM identifies itself in Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
. Between 10 and 20 minutes past the hour, RWM transmits a pulse of carrier every second, with the difference between UT1
Universal Time
Universal Time is a time scale based on the rotation of the Earth. It is a modern continuation of Greenwich Mean Time , i.e., the mean solar time on the Prime Meridian at Greenwich, and GMT is sometimes used loosely as a synonym for UTC...
and UTC in units of one-fiftieth of a second encoded onto the once-per-second pulses. Between 20 and 30 minutes past the hour, RWM transmits 10 carrier pulses each second. This transmission cycle is repeated every half hour.
RWM does not transmit the time of day, only standard time intervals.
| Minute | Duration | Signal | |
|---|---|---|---|
| :00 | :30 | 07:55 | Unmodulated carrier |
| :08 | :38 | 01:00 | Transmitter off |
| :09 | :39 | 00:55 | Morse code station identification: "RWM RWM RWM..." |
| :10 | :40 | 09:55 | 1 Hz pulses. Minute pulse 500 ms, others 100 ms, doubled with DUT1 code. |
| :20 | :50 | 09:55 | 10 Hz pulses, 20 ms each. 40 ms on the second, 500 ms on the minute. |
The 1 Hz pulses begin on the second, and are doubled (a second pulse transmitted from 200–300 ms past the second) to encode DUT1 and dUT1. Using these values, UT1 may be computed as:
- UT1 = UTC + DUT1 × 0.1 s + dUT1 × 0.02 s
DUT1 may vary between −8 and +8. The number of double pulses sent during seconds 1–8 of each minute encode positive values; if DUT1 = +5, then pulses 1 through 5 will be doubled. Doubling pulses 9–16 encodes negative values similarly.
dUT1 varies from −4 to +4. Positive values are encoded by double pulses during seconds 21–24 of each minute. Negative values are encoded during seconds 31–34.
The 10 Hz pulses are widened in a pattern similar to that of the Beta time signal
Beta (time signal)
Beta is a time signal service in the VLF range in Russia, operated by the Russian navy. There are 6 transmitter stations, which take turns transmitting time signals and other communications....
: Most pulses are 20 ms, but ones sent on the second are 40 ms, and ones sent on the minute are 500 ms.
See also
- RBU (radio station)RBU (radio station)RBU is a time code radio station located in Moscow . It transmits a continuous 10 kW time code on 66⅔ kHz. According other sources the transmitter site may be or on the area of Taldom transmitter at...
, a longwave signal transmitted from the same location. - Beta (time signal)Beta (time signal)Beta is a time signal service in the VLF range in Russia, operated by the Russian navy. There are 6 transmitter stations, which take turns transmitting time signals and other communications....
, a Russian navy time signal.