Abstract: A frequency jump radiocommunications system fixed station in which n receivers and n channels may be connected to p transmitters; p being less than n. A management circuit is provided on each of the n channels to provide signals indicating the active/nonactive state of each channel. A time/frequency law generator is provided on each channel to generate the jumped frequency signals. A general control circuit receives the active/nonactive signals and provides a connection control signal and provides a connection control signal assigning one of the n channels to one of the p transmitters. The general control circuit also generates a transmission authorization signal to authorize the p transmitters to transmit. The connection control signal is received at first and second connection matrices.

Abstract: The device is of the type comprising a circuit for compressing the dynamic of the speech signal before transmission of the signal at constant level and an expander for re-establishing at reception the speech level before compression thereof. A logic filtering circuit controls the compression circuit by constant attenuation steps depending on the speech level. A selector comparator circuit coupled by a first input to an output of the logic filtering circuit and by a second input to the output of a device controlling the expander compares the attenuation values supplied by the logic filtering circuit with those supplied by the device controlling the expander and adjusts the attenuation value of the compression circuit to the greatest of the attenuation values supplied by the logic filtering circuit or by the control device of the expander.

Abstract: A radio communications system comprising at least one master station and a plurality of slave stations in two-way frequency-hopping communication therewith. For telephony, speech is digitally encoded. Digital data is transmitted in packets using successive bursts at different frequencies separated by intervals of silence. Each slave station has its own frequency-hopping pattern independent of the patterns of the other slave stations but sharing a common pool of available frequencies. The master stations are capable of generating any of the slave station patterns instantly. The master stations broadcast network time information for synchronization purposes, and the slave station patterns are determined by a combination of a slave station identification number and network time.

Abstract: A radiocommunications system for transmitting packets of digitized data between a central station and a plurality of subscriber stations using a common set of frequencies. Each subscriber station and central station has an input circuit for compressing packets of digitized data, and a transmitter for generating a transmitter carrier wave. The carrier wave frequency of the transmitter is varied by steps with predetermined frequency values according to a frequency law assigned to the subscriber station and independent of the laws assigned to the other subscriber stations. The frequency steps are synchronous with the frequency steps of the other subscriber stations and the steps have the same duration. A processing circuit coupled between the input circuit and the transmitter calculates and inserts redundancy data into the succession of digitized data.

Abstract: Apparatus for processing speech in radioelectric transmitter/receiver equipment is adapted to transmitting and receiving speech. The apparatus comprises a compression circuit for compressing the dynamic range of the speech signal, said compression circuit being formed by at least one variable transmission attenuator for maintaining the level of speech modulation substantially constant throughout speech transmission. An expander re-establishes on reception the level of speech before it was compressed. An expander control device is responsive to the attenuation value applied by the transmission attenuator and transmitted over an auxiliary radioelectric frequency channel of the equipment. The compression circuit is an incremental compression circuit with a time anticipated action.

Abstract: Prior to each voice activity period, the transmitter supplies a digital preamble for coding the speech signal levels and during these periods high frequency signals modulated in substantially constant amplitude, but transmits nothing other than said preamble and said periods. On reception, a signal detector and logic elements control a switch to obtain only speech signals at the input of an attenuator. The preamble decoding circuit controls the attenuation value of the attenuator in order to resupply to the receiver output signals of the same relative level as those applied to the transmitter input.

Abstract: The transceiver according to the invention is controlled by an automatic alternation device in order to permit transmission solely when voice signals are to be transmitted and when the receiver does not receive such signals. On transmission, the transmitter supplies constant amplitude-modulated, high frequency signals during voice activity periods and supplies nothing outside these periods. On reception, a detector for detecting the rapid amplitude transitions of the received signals and a logic circuit control the switching off of an electronic switch during the voice activity periods, so that the output of the receiver only supplies voice signals. The gain of the receiver amplifier is controlled by an automatic control loop. The value of the time constant of this loop is controlled so as to be low during the voice activity periods and high outside these periods.

Abstract: An apparatus for synchronization in digital transmission makes it possible to control a clock circuit on the basis of the timing of a digital message having indexing bits followed by information bits. For this purpose it contains a control system, including a clock circuit, with an input connected either to the input or the output of a delay line by means of a switching system. The phase control begins with the first indexing bit received at the input of the delay line. When this control is established the input of the control system is connected to the output of the delay line. This connection brings the clock into operation on the basis of the control established and then sets off a "follow-up" operation as soon as the first indexing bit reaches the output of the delay line.

Abstract: A circuit determines whether the signal transmitted by a variable-gain amplifier comprises information or not. If it comprises information, its level is regulated, by comparison with a first reference signal, in order to give a predetermined correct listening level at the output of the receiver. If it does not comprise any, its level is regulated, by comparison with a second reference signal, in order to give at the output of the receiver the listening level corresponding to the hearing threshold.

Abstract: A telephone set for optical fibers lines having a coupler for directing a first part of the light received from the input optical fiber on a photo-cell and a second part of this light on a microphone modulating this second part without electrical intermediate apparatus, the photo-cell feed alternately a bell or a receiver, and the light modulated by the microphone is directed via a dialling system on the output optical fiber.

Abstract: An audio squelch circuit uses spectral analysis of the audio signal to derive two test signals, one of the two indicating speech presence "energy" and the other "voiced" speech presence. The two test signals are logic-AND combined to decide speech presence and open the squelch gate. Detection of speech in the audio signal, composed of a voiced segment which is both preceded and followed by a non-voiced (consonant) segment, is improved by correspondingly lengthening the "voiced" test signal pulse with both earlier (anticipatory) initiation by a time interval "D," and with a later (prolonged) completion by a time interval "d".

Abstract: Stations allowing the use of directional antennas for multiple connections between a master station and each one of subordinate stations. The antenna of a master station M rotates uniformly. When it is directed towards a subordinate station S, the informations to be transmitted, compressed to this end, are transmitted bilaterally. The expansion of the compressed information received takes place regularly. If the stations are mobile, the antennas of the stations S are equipped with an acquisition and servosystem keeping it directed towards the station M.

Abstract: The artery comprises for two-way transmission of the telephone signals first and second transmission channels coupled together at one end of the artery. In each one of a plurality of geographical points, a multiplexing-demultiplexing switching device is coupled to the artery for selectively frequency translating low frequency input channels and inserting them in vacant positions of the group of multiplexed channels transmitted by the first transmission channel, and selectively extracting from the second transmission channels the corresponding return speech signals and transposing than to low frequency, without complete demultiplexing of the group of multiplexed signals transmitted by the second transmission channel. This system allows in particular telephone communication through the artery between two subscribers whose lines may be connected to two such switching devices.

Abstract: The telephone set comprises a programmable carrier generator which supplies the same variable frequency to an amplitude modulator receiving the local voice signals, and to a synchronous demodulator which makes it possible to reconstitute, without band pass filtering, the voice signals of any set with which it is communicating among those of other sets. The double side band amplitude modulated signals supplied by each set are frequency-division multiplexed on one of the two ways of a telephone artery, the other way of which distributes them to the sets after conversion of all the carrier frequencies into conjugate frequencies thereof. The programmable generators of the calling and called users in communication are respectively tuned to the frequencies of such a pair of conjugate frequencies.

Abstract: The switching unit comprises for two-way transmission two branches, each of which includes in series an input mixer, a channel filter and an output mixer, and two variable frequency digitally controlled carrier current generators, the first of which feeds the input mixer of the first branch and the output mixer of the second branch, and the other of which feeds the output mixer of the first branch and the input mixer of the second branch. In a switching arrangement using such units, a telephone channel can be transferred from an incoming multiplexed group to an outgoing multiplexed group by means of two units whose second generators receive a common frequency, while their first generators respectively receive frequencies corresponding to the positions of the considered channel in the incoming and outgoing groups respectively.

Abstract: A channel board which simplifies wiring.Each channel board 30-31 comprises its own controlled carrier current generator for the formation of primary groups, and preferably also for the direct formation of the secondary groups from pre-modulated channels. The requisite carrier current is obtained by controlling the value of the divisor N in the frequency divider contained in the feedback loop. The control of N is effected for example simply by inserting the channel board into its location or by providing in addition with a selector plug, or by means of loaded shift registers.