RWM is the callsign of a

high frequency High frequency (HF) is the ITU designation for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one ...

(shortwave) standard frequency and

time signal A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, au ...

radio station in Moscow, Russia. It is controlled by All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology, and operated by Russian Television and Radio Broadcasting Network. Transmitting frequencies are 4.996 MHz with 5 kW and on 9.996 and 14.996 MHz 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 with simple receivers of low selectivity, 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 In telecommunications, a carrier wave, carrier signal, or just carrier, is a periodic waveform (usually sinusoidal) that conveys information through a process called ''modulation''. One or more of the wave's properties, such as amplitude or freq ...

. At 9 minutes past, RWM identifies itself in

Morse code Morse code is a telecommunications method which Character encoding, encodes Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code i ...

. 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. -- official signal specification, in russian. 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: : 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: Most pulses are 20 ms, but ones sent on the second are 40 ms, and ones sent on the minute are 500 ms.

References

{{Time measurement and standards Time signal radio stations Shortwave radio stations Radio stations in Russia

See also

References