Abstract:
Process for estimating the correlation matrix of signals of unknown characteristics in an array of N sensor. The process determines the correlation matrix {circumflex over (R)}s of the signals of known characteristics, estimates the correlation matrix {circumflex over (R)}x of the sensor signals, forms a matrix A equal to A={circumflex over (R)}s−1/2{circumflex over (R)}x {circumflex over (R)}s−1/2 and decomposes the matrix A into eigenelements, constructs a matrix B based on the eigenelements of the matrix A, and determines the estimated correlation matrix {circumflex over (R)}b of the interfering signals based on the estimated matrix {circumflex over (R)}s and of the matrix B, such that {circumflex over (R)}b={circumflex over (R)}s1/2 B {circumflex over (R)}s1/2. Such a process may find application to antenna processing.
Abstract:
Method and system for separating a plurality of users in a communication system including two transmitter antennas and N receiver antennas, said signals transmitted by said users containing symbols an, x( ) corresponding to the vector of the envelopes of the output signals of the 1 to N receiver antennas after a shaping filtering operation, characterized in that it uses a linear mean square filter extended over an observation vector {tilde over (x)}=[x(2n−1)T x(2n)T x(2n−1)H x(2n)H]T where x(2n−1) and x(2n) correspond to the (N×1) (N≧1) observations at the symbol times 2n−1 and 2n.
Abstract:
Method for measuring certain parameters of the impulse response of a propagation channel involving emitters and reflectors that are fixed or mobile, so as to detect and determine the parameters regarding the position and kinematics of these emitters and reflectors, or to auto-locate the reception system implementing the invention, in a system comprising N sensors receiving signals from said emitters or from the reflection on said reflectors, and comprising at least the following steps: determination of an ambiguity function which couples the spatial analysis and the delay-distance/Doppler-kinematic analysis, determination of at least one sufficient statistic C(l, m, K) corresponding to the correlation between the known signal s(kTe) corresponding to the complex envelope of the signal emitted and the output of a filter w(l,m) where l corresponds to a temporal assumption (delay-distance, temporal ramp, etc.) and m to a frequency assumption (Dopper-kinematic, Doppler ramp, etc.), determine the values of the pair (l, m) by comparing the value of the statistic for the pair (l, m) with a threshold value.
Abstract:
A bipolar transistor having a base region resting by its lower surface on a collector region and surrounded with a first insulating layer, a base contact conductive region in contact with an external upper peripheral region of the base region, a second insulating region in contact with an intermediary upper peripheral region of the base region, an emitter region in contact with the central portion of the base region. The level of the central portion is higher than the level of the intermediary portion.
Abstract:
A bipolar transistor with very high dynamic performance, usable in an integrated circuit. The bipolar transistor has a single-crystal silicon emitter region with a thickness smaller than 50 nm. The base of the bipolar transistor is made of an SiGe alloy.
Abstract:
A device and method for the calibration and equalization of reception chains of an antenna processing system comprises several RF chains, each associated with a radiating element, a set of sensors Ci formed out of the outputs of the preceding RF chains, a channel for the injection of a calibration signal, means to couple the calibration signal to the sensor signals and several reception-digitization chains. The device comprises at least one processor adapted to managing all the devices; a means used to adjust the value of the gain of an RF chain to a minimum value Gmin; a means for deflecting the sensors, adapted to minimizing their directivity toward the interference sources; a means adapted to adjusting the level of the injected calibration signal ST relative to the signal of the sensors, an RF chain having a gain adjusted to a minimum value Gmin.
Abstract:
A method for the verification of anti-jamming in a communications system comprises several sensors or adaptive antennas, comprising at least the following steps: estimating the mean power π;ˆy of the output of the communications system, estimating the respective power values Pu or P′u, of a station u, the antenna noise Pa or P′a, the thermal noise PT, or P′T, estimating at least one of the following ratios: J tot / S tot = ( ∑ p = 1 P ; ; P p ) / ( ∑ u = 1 U ; ; P u ) J tot / S u = ( ∑ p = 1 P ; ; P p ) / P u J u / S u = ( ∑ p = 1 P ; ; P pu ) / P u comparing at least one of the three ratios with a threshold value.
Abstract:
A process and device related to multisensor radio direction finding receivers usable in radio communication systems including several emission sources. The process and device isolate the contribution of each emission source in sensor signals so as to perform direction finding on a single emission source only, based on learning sequences inserted into waveforms emitted by each of the emission sources. Such a process and device may find particular application to cellular communication networks.
Abstract:
A method for measuring certain parameters of the impulse response of a propagation channel involving emitters and reflectors that are fixed or mobile, and for detecting and determining the parameters regarding the position and kinematics of the emitters and reflectors, or for auto-locating the reception system implementing the invention, in a system comprising N sensors receiving signals from the emitters or from the reflection on the reflectors. The method determines an ambiguity function which couples the spatial analysis and the delay-distance/Doppler-kinematic analysis, and determines at least one sufficient statistic Ĉ(l,m,K) corresponding to the correlation between the known signal s(kTe) corresponding to the complex envelope of the signal emitted and the output of a filter w(l,m) where l corresponds to a temporal assumption and m corresponds to a frequency assumption. The method also determines the values of the pair (l,m) by comparing the value of the statistic for the pair (l,m) with a threshold value.
Abstract:
A method of fighting interference in a frequency-hopping communication system is disclosed. The system has at least one main sensor and one or more auxiliary sensors. According to at least one embodiment, frequency-hopping signals are received. The frequency-hopping signals are arranged to include useful bands and one or more guard bands inserted between the useful bands, and a ratio of the useful bands to the guard bands being chosen according to a predetermined value of probability of interference interception. Signals of the inserted guard bands having a signal level greater than a predetermined threshold are selected. A set of spatial-filtering weightings are calculated according to a correlation matrix of noise plus jammers alone on the signals selected. Baseband signals of the received frequency-hopping signals are filtered by the set of the calculated spatial-filtering weightings.