Radio silence
In shipping, radio silence is understood as the cessation of radio traffic at all radio stations of the maritime radio service in order to ensure the reception of emergency signals and to listen to the emergency frequencies. Radio silence is sometimes also ordered on military radio networks to prevent the enemy from tracking their own units . Finally, the term radio silence in a figurative sense still describes the state in which two or more parties no longer talk to each other and avoid contact.
Maritime communications
In ship radio traffic, three-minute radio silences four times an hour are prescribed in order to be able to receive weak signals if necessary:
- on the international radio emergency and calling frequency (2182 kHz) twice an hour:
from xx.00 a.m. to xx.03 a.m. (every full hour) and from xx.30 a.m. to xx.33 a.m. (every half hour) - on the international emergency frequency 500 kHz ( telegraph
radio ), which is mandatory on so-called “equipment-requiring” ships, twice an hour: from xx.15pm to xx.18pm and from xx.45pm to xx.48pm
During the radio silence, all radio communications with the exception of emergency communications must be avoided. The times of radio silence are highlighted on the radio clock, which should be placed in the field of vision of the radio operator, by colored sectors (mostly red and green, sometimes blue instead of green).
Long-term radio silence is mandatory as soon as an emergency call has been received, i.e. Mayday on radio or the telegraphy emergency signal SOS ( · · · - - · · · ), or the emergency signal of an EPIRB . Then each marine radio station may warn each other to remain silent: in the radio with the message SILENCE MAYDAY , in the telegraph with the QRT SOS sign .
The cancellation of the radio silence due to the termination of the emergency traffic is carried out by the message SILENCE FINI from the leading radio station. All standardized phrases in marine radio are pronounced in French.
Military radio silences
In the military, any sea, land and even air units can be ordered to radio silence. This means that the units can still receive orders by radio, but cannot confirm them in order not to reveal their own position or even their presence. Otherwise, even if the enemy cannot decipher the message, the enemy could intercept the signals and deduce certain enemy actions from the number and duration of the radio messages and possibly also locate the position of the transmitter by means of bearing.
Other radio silences
- Funkstille is a novel from the Shadowrun series . Volume 25 by writer Jak Koke, published in 1997, bears this title.
- In many of the BOS radio networks in Germany, all participants are requested to remain silent by the control center before sending a 5-tone sequence .
