Abstract: A system and a method for communication between at least one user in a high-frequency HF communication system comprising at least one transmission site and at least one reception site, the two sites being remote from one another by a distance D, comprises at least the following steps: scanning the signals or frequencies by using a wide band receiver, detecting whether there is a request to establish a communication link contained in the signals received on the receiver, if yes, then transmitting this link establishment request to the transmitting equipment item which will check whether it is possible to establish a link and, if it is, which will determine a possible configuration and establish a communication mode for the mobile user, if not, then returning to the step in which the signals received on the reception site of the system are scanned.

Abstract: An antenna structure for a carrier connected to a station by a coaxial cable comprises at least the following elements: a break delimiting a first portion of length H1 and a second portion of length H2, forming a radiating element isolated from a second section by means of a current isolator, at the break, the core of the coaxial cable from the lower face of the break is connected to the braid of the coaxial cable from the upper face of the break and the core of the coaxial cable from the upper face of the break is connected to the braid of the coaxial cable from the lower face of the break, the first upper portion has a recess in the coaxial cable suited to inserting a short circuit for signals whose frequency is equal to the operating frequency.

Abstract: An antenna structure for a carrier connected to a station by a coaxial cable comprises at least the following elements: a break delimiting a first portion of length H1 and a second portion of length H2, forming a radiating element isolated from a second section by means of a current isolator, at the break, the core of the coaxial cable from the lower face of the break is connected to the braid of the coaxial cable from the upper face of the break and the core of the coaxial cable from the upper face of the break is connected to the braid of the coaxial cable from the lower face of the break, the first upper portion has a recess in the coaxial cable suited to inserting a short circuit for signals whose frequency is equal to the operating frequency.

Abstract: A telecommunications system comprises a number of remote subnetworks, a subnetwork comprising at least one tactical radio node NRT serving as gateway between said subnetwork and a backbone network consisting of at least one airborne communication node. An NRT node communicates with the airborne communication node by converting the wave form of the signals to be transmitted outside the subnetwork being associated with it into a wave form used by the airborne communication node, said airborne communication node transmitting the duly received signal without modifying its wave form to at least one NRT node belonging to another subnetwork. A tactical radio communication node and an airborne communication node are also disclosed.

Abstract: A method and apparatus for spatial multiplexing and demultiplexing of radio signals. A multichannel transmitter and receiver is integrated in a base station and coupled to an antenna array. Using digital radio signals containing previously known or non-Gaussian sequences and arranged in frames, the spatial information about each mobile unit is estimated on the basis of the signal received by the receiver for the reception and transmission frequencies. This is done by known sequences or by blind source separation methods. The respective paths of each mobile unit with the power above a predetermined threshold is isolated by spatial filtering in the presence of multiple channel paths in order to provide spatial demultiplexing.

Abstract: A process which adjusts the transmission and reception chains of the paths formed by a base station of a system for radio communication between mobiles which after calibration of the antenna base adjusts the reception chains relating to each path by distributing a first specified adjustment signal synchronously over each of the reception chains and calculating an equalization filter which inverts the transfer functions related to each reception chain. The process next adjusts the transmission chains related to each path by distributing a second specified adjustment signal synchronously over each of the transmission chains, by extracting from each of the paths a part of a transmission signal before the transmission signal is sent to the antenna base so as to re-inject that part of the transmission signal into the reception chains, and by calculating an equalization filter which inverts the transfer functions related to each transmission chain.

Abstract: Disclosed is a method enabling the improvement of the multisensor reception of a system of radiocommunications exchanging signals between at least one fixed base station providing for multisensor reception by means of a network of sensors, and the processing of the signals. This method consists, in a transparent manner perceived from the base station, in computing a weighting vector W for the formation of channels at reception. The weighting vector W is estimated by an adaptive algorithm leading to a maximization of the signal-to-noise ratio. Application: mobile radiocommunications. FIG.

Abstract: The method consists in the step of masking the energy influence of the aliased spectrum of a jammer received in the useful band of each of the reception channels of a radio station during a determined time interval surrounding the change-over instant of each antenna. The masking is done either by means of attenuators with diodes placed at the input of each of the reception channels and controlled during the determined time interval or by memorizing, at least during the time interval, the gain of the intermediate frequency amplifiers before the change over takes place, by opening the automatic gain control loop of the intermediate frequency amplifiers to stabilize the gain of each amplifier, during the change over, at its memorized gain value.