Nec Corporation

Tomoyuki Ooi

Toshinori Hotta

Yasuhito Isoe

In a method for controlling a burst output timing in a satellite communication system for performing radio communication between a central earth station and a plurality of remote earth stations via a satellite, the time between a transmission of burst data from each of the remote earth stations to the central earth station via the satellite and the reception of the burst data returned from the central earth station via the satellite is time-counted. The output timing of the burst data transmitted from each remote earth station is adjusted, when the burst data is to be sent to the central earth station, in accordance with a time difference between the time and a preset reference time. A burst output timing control system is also disclosed.

Burst output timing control system in satellite communication system

A phase ambiguity removing device for determining the proper phase of the Pch, Qch data demodulated by a receive side demodulator of a Quadrature Phase Shift Keying (QPSK) system includes a second phase information controller for determining the most probable phase of the received signals when detection of synchronizing words fail in the Pch and Qch signals.

Phase ambiguity removing device

In a communications system, a multiframe data signal is sent from a transmit end to a receive end of the system. The multiframe is composed of a series of submultiframes each containing a series of frames. Each frame in turn comprises a sync word for establishing the start timing of the frame, an identifier for uniquely identifying the submultiframe in which the frame is contained, and a specified number of data bits. A pseudo-random scrambling bit pattern, which repeats at intervals of multiframe and varies from one pattern to another at frame intervals, is generated as a scrambling bit pattern with which the data bits of each frame are scrambled prior to transmission. At the receive end, the sync word of each frame is detected to establish frame synchronization. A memory stores initial bit patterns each of which is identical to the pattern which was generated at the beginning of each submultiframe. The identifier is detected when frame sync is established and applied as a read address to the memory. The initial bit pattern of the submultiframe which is next to a one in which the establishment of frame sync occurred is read out of the memory into a pseudo-random sequence generator. The latter is activated at the beginning of the next submultiframe to generate a pseudo-random sequence, which successively varies at frame intervals and repeats the same pattern at multiframe intervals, for descrambling received data bits.

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Tokyo, Japan

Tomoyuki Ooi