Societe Nationale D'etude Et De Construction De Moteurs D'aviation

Bruno R Sebilet

Michel J Nicolas

Guy Le Garrec

Gerard D Fourreaux

Alain Saussier

Patrice C Delon

A method of simultaneously transmitting first and second data signals by the technique of spectrum spreading by direct sequence, comprises using the first data signal to modulate a spreading code produced by a code generator from a code clock and using the second data signal to modulate the delay of the spreading code. Modulation of the spreading code delay comprises either modifying the delay of the code delivered by the code generator, or modifying the code clock frequency. Apparatus for carrying out this method is also described.

Method and apparatus for the simultaneous transmission of separate data

A bidirectional data transmission system using the technique known as spectrum spreading by direct sequence comprises a first transmitter-receiver assembly consisting of a first transmitter section which generates a coded first data signal for transmission by modulation of a radioelectrical carrier by a spreading code of which the delay is modulated under the control of the first data, and a first receiver section which receives a coded second data signal and restores the second data therefrom, and a second transmitter-receiver assembly consisting of a second transmitter section which generates the coded second data signal for transmission by modulation of a transmission carrier by a spreading code, the carrier itself being modulated by the second data, and a second receiver section which receives the coded first data signal and restores the first data therefrom by demodulation of the delay in the spreading code contained in the coded first data signal, the restored first data being used to control the delay of the spreading code generated for the second transmitter section.

Bidirectional data transmission system

A continuous emission radar device for determining, at short range, the relative positions of a missile and a vehicle to which the device is fitted, includes a transmitting circuit connected to a transmitting antenna for emitting a continuous signal modulated by a pseudo-random binary sequence delivered at a clock frequency fH, and three receiving circuits connected respectively to three receiving antennae which receive echos of the emitted signal from the missile, a first receiving circuit generating the clock frequency and slaving it to the missile vehicle distance, and the other two receiving circuits determining the phase shift between the echo received by the first antenna and each of the echos received by the other two antennae, these three parameters being transmitted to a device for calculating the position of the missile in relation to the vehicle.

Continuous emission radar device for determining, at short range, the

In a method of coding and decoding a broadband transmission of the spread spectrum type, the signal to be transmitted is encoded by modulation in accordance with a code consisting of a pseudo-random binary sequence of period T composed of two alternating half-sequences of period T/2 and having virtually nil cross-correlation. In the receiver a reception code is generated which is the same as the transmission code except that one of the half-sequences of the reception code is shifted in a circular rotational sense relative to the corresponding half-sequence of the transmission code. This reception code enables synchronization of the transmission and reception code generators by correlation of the reception code with the received coded signal using only one correlator, and is also used to control a demodulator for decoding the received signal.

Method and device for coding and decoding a broadband transmission

In a process for coding of radio transmissions by spectrum spreading, a signal is phase modulated by means of a 0-pi modulator controlled by a psuedo random sequence formed by combining in accordance with a logical majority function an odd number of elementary codes constituted by pseudo random binary sequences of different lengths. On reception, the synchronization of the code which controls the demodulator is realized by correlating each of the elementary codes with the received signal.

Spread spectrum coding method and apparatus

A proximity radar is described in which a signal phase modulated in accordance with a pseudorandom sequence is transmitted from an antenna, and a return signal reflected from a target is received by this antenna. The return signal is correlated with a signal identical to the transmitted signal but delayed by a selected time interval. The delay imposed on the transmitted signal as fed to the correlator is alternately given the two values n.t and n'.t where n' is less than n and the time interval n.t corresponds to the time taken by the signal to travel to and return from the target when the radar is at a predetermined distance from the target, which distance is to be detected. The correlator output is fed through an amplifier circuit including an automatic gain control circuit when the delay is n'.t and the automatic gain control circuit is inoperative when the delay is n.t.

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Rueil Malmaison, France

Bruno R Sebilet