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REA4

Enigma ID n/a
Name REA4
Frequencies
Status Active
Voice N/A
Emission mode OOK (A1A); FSK, 1000 Hz shift (F1A)
Location Moscow, Russia; Irkutsk, Russia; Khabarovsk, Russia

Russian (icon)

Activity pages

REA4 is a Morse code broadcast network of the Long-Range Aviation that sends weather bulletins and "Monolith" messages. It covers the entire country using three transmitters.

The Moscow transmitter alternates between two pairs of frequencies, one each for daytime and nighttime. The times listed are Moscow time (UTC+3).

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Daytime 4649, 7314
09:00-16:00
5293 4835 4316 4649, 7314
09:00-16:00
Nighttime 2737, 4179
16:00-09:00
4379 4316 4379 2737, 4179
16:00-09:00

The Irkutsk and Khabarovsk transmitters alternate between three frequencies, one each for daytime, dawn/dusk, and nighttime, several hours apart from each other.

  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Daytime 10981
10653
12337
10653
10981
Dawn/Dusk 7785
7515
7402
7515
7785
Nighttime 6087
5853
?
5853
6087

Weather bulletins

REA4 broadcasts weather bulletins every hour at 40 minutes past. The format used is SYNOP with the following variations:

  • In the date/time groups, midnight is represented as "24", not "00"
  • The time zone given can range from UTC-2 to UTC+3, although UTC-1 is the most common
  • The weather station IDs do not begin with a country code

The weather bulletins come from at least eight different airfields using the following 5-digit IDs:

A typical REA4 weather bulletin with translation:

REA4 REA4 = 20100 99900 19150 27627 81997 21702 10014 21015 70300 82031 912// = REA4 K
  • 20100 - 20th of the month at 10:00
  • 99900 - Standard weather broadcast type
  • 19150 - Beginning of the observation period; here: 19th of the month at 15:00
  • 27627 - Airfield identifier
  • 81997 - Manned weather station, weather group included, cloudbase above 2500 m, visibility 10 km
  • 21702 - 2/8ths total cloud cover, 170° wind direction, 2 m/s windspeed
  • 10014 - +1.4°C temperature
  • 21015 - -1.5°C dewpoint
  • 70300 - Clouds developing from previously clear skies
  • 82031 - Mid-level altocumulus translucidous and high-level cirrus fibratus
  • 912// - Observation made during the 12th hour, minutes omitted

Very often, a weather bulletin is repeated for several hours in a row, with only the first date/time group changed.

"Monolith" messages

Occasionally, REA4 transmits "Monolith" messages to the following callsigns:

1QRF, 7XMF, HA57, JUE4, JZLB, L9XC, MJUR, MSK7, PABA, QMCK, REA4, RLO92