Abstract: A transmitting-receiving station for transmitting information by frequency hopping comprises a code generator to define the use of a plurality of channels in accordance with a high-speed skip law for a transmitting-receiving station in the stand-by mode, the high-speed skip law consisting in the use of each of the channels during a period of time Tp, while the low-speed skip law governs the change of listening channels used during N.times.Tp, each corresponding to a center channel out of a sequence of N channels of the high-speed skip law. The center channel contains a synchronizing code. The station comprises a memory device to which a write circuit for progressively storing therein the codes produced by the generator and also to which a read circuit is connected to take the codes from the memory as a function of the positions of the transmitting-receiving station.

Abstract: A time-division-multiplexing loop telecommunication system has a first and a second transmission line for linking up a succession of connecting circuits and for supplying information, in a normal service direction of transmission, to subscriber circuits attached to the connecting circuits; these connecting circuits are provided with an input and an output for the connection of subscriber circuits, with up-line and down-line access points connected to the said lines. Typical of this system is that at the level of each connecting circuit provision is made for means of command for linking the input of the subscriber circuits to one of the up-line access points receiving the infromation, while the output is linked to the down-line access points.

Abstract: This arrangement for re-arranging information has for its object to transmit time-division multiplexed information obtained from incoming time-division multiplexed information. These multiplexers are formed by fast-rate channels and slow-rate channels; the arrangement for re-arranging information comprises a set of memories (M0 to M7) which have a data input (12) and a data output (SM) and to which there are connected on the one hand a write circuit (21) for writing therein, at the rate of the incoming multiplexed information, the information from this multiplex, and on the other hand, a read circuit (50) for applying to the outgoing multiplex, at its rate, the information contained in the said set of memories.

Abstract: In order to reduce the noise signal of an acoustic origin contained in an input signal coming from a microphone located in a noisy environment, a noise reducing arrangement includes a filter (6) which receives the input signal and eliminates a frequency band of some hundreds of Hertz, centered around the average frequency of the first formant of the speech signal, a detector circuit (7) detecting the output signal of the filter (6) with a time constant to the order of some tenths of a second, finally a variable-threshold circuit (9) which uses the detected signal as the threshold signal and which is arranged for transmitting the variations of the input signal when the latter has an absolute value which is higher than the threshold signal.

Abstract: This closed loop multiplex communication system uses a timing unit to establish a general multiplex format consisting of 1024 frames in a multiframe. Each subscriber station transmits one message bit per frame (i.e. 1024 message bits per multiframe), but transmits only 32 signalling bits per multiframe (i.e. the eight-bit non-message blocks in four corresponding frames).