International Business Machines Corporation

Jean L Monrolin

Alex H Lautier

Pierre Vachee

Binary/ternary transmission process and device. Several trains of binary signals are time-multiplexed by using registers RG1 and SER to generate a first binary sequence L applied to an ENCODE unit which also receives a second binary sequence D and clock information CP. When the information of sequence L is at one binary level, the resulting signal is coded in bipolar code. When the information of sequence L is the other binary level, the resulting signal is coded in biphase code.

Data transmission method and devices for practicing said method

A method and a system are disclosed for synchronizing within a recurrent time frame the starting points of the transmissions from the various stations in a TDMA network wherein N stations distributed among M separate zones covered by M different down-link frequencies exchange pulse bursts through a satellite, each pulse burst being comprised of a preamble, a unique word, the transmitting station's address, and traffic data. The satellite includes a global beam antenna which covers all of the M zones and is adapted to receive M different up-link frequencies, means for converting these M up-link frequencies to M corresponding down-link frequencies, and M directional beam antennas covering the M zones, each of said M antennas being adapted to transmit the down-link frequency associated with the particular zone it covers. The bursts transmitted by the various stations are assigned a predetermined position within the frame. Each station detects whether it has received a unique word followed by the address of a given station. Upon detecting such an address, the station activates timing means which define a time interval associated with the station whose address has been detected and, at the end of that time interval, starts transmitting M successive bursts respectively destined for the M zones during predetermined time intervals within the frame. These M bursts are transmitted at different up-link frequencies so that the burst intended for a given zone will be transmitted at the up-link frequency corresponding to the down-link frequency for that zone. In accordance with an embodiment of the invention, the timing means comprise M timers respectively defining N time intervals associated with the N stations. The start of a station's transmission is determined by the timer which reaches its stopping point first.

Method and system for synchronizing a TDMA communication network

A receiver for a data transmission system employing the interleaved binary phase shift keyed modulation technique. The received signal is demodulated by means of an in-phase reference carrier and a quadrature reference carrier both of which are supplied by a clock and carrier recovery device, thereby supplying the in-phase and quadrature components of the signal. The sign of the sum of these components and that of the difference between them are selectively gated to the output of the receiver under control of the clock signal supplied by the clock and carrier recovery device. In this device, the frequency of the received signal is doubled and the signal thus obtained is modulated by the clock signal at half the signaling rate extracted from the received signal. This modulation operation yields a signal at twice the carrier frequency from which the in-phase and quadrature reference carriers are extracted.

Receiver for data transmitted by means of the interleaved binary phase

This invention concerns a carrier synchronization system for a four-phase coherent PSK demodulator. The four-phase PSK signal is demodulated by an in-phase reference carrier and a quadrature reference carrier both of which are locally generated by a reference carrier source. The in-phase and quadrature components of the four-phase PSK signal that result from these demodulation operations are delayed a time interval substantially equal to T/2 seconds, T being the signaling period. The product of the delayed in-phase component and the sign of the quadrature component is compared with the product of the delayed quadrature component and the sign of the in-phase component, to produce a phase error signal. This error signal is used to control the adjustment of the reference carrier source.

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LaGaude, France

Jean L Monrolin