Abstract: In radio operation in tactical use, an increased jamming resistance with respect to intentional jamming is required. For protection against intentional jamming, frequency hopping techniques have proven very advantageous in which the signals are transmitted in the form of successive error-protected signal blocks where each signal block is transmitted on a different radio carrier frequency which changes in a pseudo-random manner. With this technique, phase shifts can occur which are greater than half a bit and therefore make analysis of the signal blocks difficult or impossible. It is proposed herein that each received signal block be checked after regeneration in a regenerative repeater, controlled by a bit clock pulse, as to its correct block phase and therefore, respectively, newly establish the block clock pulse phase required for further accurate processing of a signal block.

Abstract: A method for jam-resistant transmission speech signals by radio which have been processed via vocoders, utilizing spread spectrum multiple access modulation (SSMA) or rapid frequency hopping (FH) provides, with respect to the danger of an inherent jamming brought about when a great number of stations simultaneously use the same frequency band for the same radio channel frequency group, activation and deactivation of the transmitter and receiver at the rate of the internal system frame clock pulse during a frame clock pulse period only when useful information is present. In this manner, in the case of simplexcommunication connections, on the average approximately 40% and, in the case of duplex operation, more than 60%, of the transmitting time can be saved, and hence, the inherent jamming of the system can be reduced in a corresponding fashion.

Abstract: In an installation for identification friend or foe, coded interrogations and replies of an interrogation installation of the interrogating station and of a transponder of the interrogated station are transmitted in utilizing a radiotelephony installation. The transmission of the reply (identification) proceeds according to the frequency jumping procedure via the radiotelephony installation. The interrogation of the interrogating station consists of a known encoded code word and an encoded variable data part which contains (or comprises) a frequency address. The making available (or offering) of the transmit frequencies of the transponder proceeds by means of a frequency synthesizer controlled (or operated) by the frequency address. The reply is, in certain circumstances, repeated on several, successively transmitted frequencies.