Abstract: A military radar or radio communication system comprises, in particular, mobile transmitter-receiver apparatus wherein a plurality of operating frequencies are constantly changed in accordance with a frequency hopping schedule. The system is particularly characterized in that the transmitter, during such time intervals in which it is not used for the purpose of useful signal transmission, for example during pauses in speech is utilized for interference on frequencies for partial frequency ranges not required at that time for the purpose of useful signal transmission, and that, to this end, a corresponding transfer installation, preferably pre-programmed or remotely controlled by a central station, is provided in the transmitter.

Abstract: A radio communications transmission system in which the communication information is digitalized and impressed on a radio frequency carrier by means of frequency modulation and/or phase modulation and wherein at the receiving station the interference is recognized as amplitude modulation occurring at the output of the intermediate frequency stage and wherein when such interference occurrence is recognized the received data is identified as being faulty and is replaced by redundantly transmitted data which is received and stored at the receiving side so as to provide accurate transmission of data.

Abstract: A directive radio communication transmission system in which the radiation between the receiver and transmitting antenna is automatically and continuously changed in direction by causing the antenna pattern to vary in the vertical direction from a reference beam direction and in small angular adjustments relative to the half-power beam width.

Abstract: A system for the reception of digital communication signals which are impressed in the form of a frequency modulation upon a carrier such that they are reflection free and can be used particularly for mobile stations, long distance traffic and scatter beam connections.