Abstract: An equipment embodying the invention is designed for bit-level quality check of a digital link in the presence of real traffic. The equipment complies with CCITT recommendations and comprises two checking stations (SP, SS) respectively located at two ends of the digital link (LT) and connected to one another by a service link (LS). First and second check information relating respectively to groups of transmitted frames (MTn.sub.p) and to groups of received frames (MTn.sub.s) are calculated in the stations and comparisons are made in order to detect the transmission errors. The check informations and the frame groups concerned by the transmission errors are transmitted from one station to the other via the service link. Processing circuits are distributed among the stations thereby processing the frame groups concerned by the transmission errors, i.e., analyzing at bit level the errors in the erroneous frames and deriving statistical information and recordings relating to said errors.

Abstract: The device comprises an echo cancelling circuit receiving a first signal and a second signal and a real echo between channels for producing a third signal containing the second signal and a difference between the real echo and the estimated echo. Detectors detect the echo difference and the second signal in the third signal when the level of the third signal exceeds a predetermined threshold. Circuits gain-control the adaptation in the adaptive filtration of the echo cancelling circuit in such a way as to modify the adaptation gain when the second signal is not detected and to prohibit all filtration modifications as long as the second signal is detected. For instance, for an acoustic echo in a telephone set, the echo is not processed when the third signal contains a local speech signal as second signal.

Abstract: A method and device are provided for encoding-decoding an HD digital television signal into a narrow band encoded signal. The HD digital television signal is representative of high definition images sampled at a frequency f1, and the narrow band encoded signal corresponds to a narrow band signal sampled at f2, wherein f2<f1. Narrow band encoding is achieved by horizontal compression by decimation of the image lines of the HD digital television signal so as to bring the number N1 of useful pixels per image line to a value N2=.alpha. of the sampling frequencies, so as to thus form an encoded signal representative of an image line and obtain reduced format high definition images. A narrow band encoded signal representative of digital television signals can thus be broadcast over an HD-MAC NB type channel.

Abstract: The method is founded on the GUAZZO algorithm and is adaptive as it does not require any prior statistical knowledge of source of message to be coded. The message is comprised of a sequence of symbols of the source which are represented by the indication of the direction "0" or "1" chosen at each node of a binary tree. According to the invention, the adaptiveness is obtained by associating with each node two finite-sized counters that count the "0"s and "1"s according to the routing of the tree. The contents of these counters enable the conditional probability of each of the elements "0" and "1" to be estimated at the node.

Abstract: The radio system embodying the invention comprises a central station and a passive terminal station. First and second data signals are transmitted between data processing units respectively connected to the central and terminal stations. The terminal station comprises a same low-cost circuit associated with a square two-dimensional antenna for detecting the amplitude of a first incident microwave emitted by the central station thereby recovering the first data signal and deriving, in response to the first microwaves, a microwave modulated in phase by the second data signal by means of a retroreflection of a second incident microwave. This second incident microwave is emitted by the central station to the two-dimensional antenna of the terminal station. The terminal station is of very simple design, is compact and can therefore be included as well as the corresponding data processing unit in a contact-free chip card.

Abstract: Method for coding a digital signal, a coder and decoder for implementing this method, a regeneration method and a corresponding regenerator. On each bit time, a detection is made of the possible presence of a binary pattern from any number "n" of binary patterns including at least two bits; the bit time is divided into "n" equal time intervals to which "n" temporal positions are associated; a correspondence is established between each of "n" binary patterns and each of "n" temporal positions; if one of the binary patterns is present, a pulse occupying a temporal position corresponding to the binary pattern is generated and the next detection for the possible presence of a binary pattern is made from the bit following the last bit of the binary pattern whose presence is detected.

Abstract: A filtering cell including a resonant circuit having an inductor and capacitor connected in parallel, the inductor being separated into two identical inductors which are connected in series with a midpoint therebetween. A second capacitor is connected at the midpoint and has a quality factor substantially equal to a quality factor of the first inductor, resulting in attenuation at the resonant frequency. Each of the inductors and capacitors are formed by micro-ribbon technology.

Abstract: Device able to continuously tune a coherent and rectilinearly polarized light source. It includes an electro-optical device (5) forming a spectral filter with an electrically modulable transfer function, this electro-optical device being provided so as to select a particular longitudinal mode from all the longitudinal modes able to oscillate inside the external cavity for which the source (1) is provided and which is ended by a reflecting device (3) towards the source of the light emitted by this source, and an electro-optical device (4) for varying the optical length of the cavity, this variation device being placed in the cavity and provided so as to continuously move the position of the selected longitudinal mode, each electro-optical device including a compact electro-optical crystal.

Abstract: A sound signal coding method and installation are disclosed, which method, usable particularly for transmitting or storing high quality audio signals in digital form, involves chopping the sound signal into blocks of samples and subjecting the samples of each block to time-frequency transform coding whose coefficients are transmitted in digital form, the reverse operations taking place at reception. At least the most significant coefficients of the transform of each block are subjected to predictive and adaptive coding using the stationary state of the signal over a duration greater than that of a block.

Abstract: The method embodying the invention authorizes communication bit rate reservations in a packet switching network. According to the method, a new communication is only accepted by the network if the communication does not exceed a maximum bit rate flowable by the switches of the network. A packet switch in the network comprises a bit rate reservation device for memorizing bit rate informations that are representative of total bit rates flowed by the switch and for processing said information as a function of data carried by service packets. The bit rate reservation device mainly comprises registers respectively associated with multiplex ways of the switch for memorizing the bit rate informations, an adder for incrementing and decrementing the bit rate informations as a function of service packet data, and a comparator for detecting overstepping of the maximum flowable bit rate.

Abstract: An Electro-Optic modulation method and device using a low-energy oblique transition of a tightly coupled super-grid. According to the present invention, a luminous beam is injected into a tightly coupled super-grid and an electric field (E) is applied to the super-grid whose amplitude is made to gradually vary so as to cause the intensity of the beam to vary. This beam is injected parallel to the plane of the films of the super-grid which guides the injected beam. The electric field is weak and applied along the growth direction of the super-grid, which provokes the appearance of a low energy oblique transition (TB) in a domain of wavelengths where the super-grid is transparent in the absence of any electric field. The super-grid is one whereby the wavelength of the luminous beam is contained in this domain. Such a device may find application in optical telecommunications systems.

Abstract: A device for the electric characterization of samples, comprises a UHF resonator intended to be coupled locally to the sample. The resonator is formed by a microstrip or triplate line loop (20) carried by a conducting plane (16) and having a gap of small length with respect to the length of the loop and an assembly (32) for receiving the sample in a position in which the sample is coupled selectively to the edges of the gap without being interposed therebetween. The edges of the gap of the loop are fixed to two electrodes of small area passing through a thin plate of dielectric material having a flat face for application against the sample.