Die Gedenkmünzen der Deutschen Demokratischen Republik wurden von der Münzprägeanstalt der DDR von 1966 bis 1990 mit 122 unterschiedlichen Motiven produziert. Vier davon hatten als Währungsbezeichnung MDN (Mark der Deutschen Notenbank), alle anderen Mark.Sie bestanden aus unterschiedlichen Legierungen mit Münzwerten von 5, 10 oder 20 Mark.. Die seltenste …

Iridium Communications Inc. (formerly Iridium Satellite LLC) is a publicly traded American company headquartered in McLean, Virginia.Iridium operates the Iridium satellite constellation, a system of 66 active satellites used for worldwide voice and data communication from hand-held satellite phones and other transceiver units. The nearly polar orbit and communication between …

Necessity. The standard method of communication between an air traffic controller and a pilot is voice radio, using either VHF bands for line-of-sight communication or HF bands for long-distance communication (such as that provided by Shanwick Oceanic Control).. One of the major problems with voice radio communications used in this manner is that all pilots being handled by a …

Matrix is an open standard and communication protocol for real-time communication. It aims to make real-time communication work seamlessly between different service providers, in the way that standard Simple Mail Transfer Protocol email currently does for store-and-forward email service, by allowing users with accounts at one communications service provider to …

A dial tone is a telephony signal sent by a telephone exchange or private branch exchange (PBX) to a terminating device, such as a telephone, when an off-hook condition is detected. It indicates that the exchange is working and is ready to initiate a telephone call.The tone stops when the first dialed digit is recognized. If no digits are forthcoming, the partial dial procedure is invoked ...