International Business Machines Corporation

Daniel Pilost

Michel F Choquet

Jacques Belloc

Victor Spagnol

Dominique Rigal

Maurice Cukier

Michel Y Quintin

Jean Cholat-Namy

Simon Huon

Francois De Saint Michel

Andre Vade

Modem receiving from/transmitting to a DTE data bits at a rate DR and adapted for operating at a modulation rate MR in an environment operating at a basic rate BR. In the receiving way, it comprises a first means for converting a number X of samples received at a frequency FS into a number X times MR/BR of samples before processing these samples by the signal processor whereby the processing results in DR/BR words of DR/MR bits, and second means for converting the DR/BR words into DR/MR words of DR/BR bits to be transmitted to the DTE. For the transmitting way the first and second converting means, are the same means but run in the reverse order. The result is that such an adapted modem behaves as a modem operating at a modulation rate MR on a periodic process interval of DR/(BR times MR) seconds.

Modem having a software-adapted modulation rate

Data multiplexing system for dispatching an input serial bit stream onto a plurality of ports, or multiplexing the data bits received from a plurality of ports as a serial bit stream. The system mainly comprises for each port, a mask register (14) loaded with a N-bit mask work wherein bits set to 1 indicate which bits of an aggregate register (10 or 56) are to be loaded or to be transferred, and a scan counter (20 or 46) starting being incremented at a high frequency at each transition of a first category, up or down, of a clock circuit (12 or 40), until the mask bit corresponding to the scan counter contents is a bit 1, whereby the corresponding cell of the aggregate register is transmitted to the associated port or loaded with the bit received at this time by the associated port.

Multiplexing system setting through mask registers

A DTE can control the modems attached thereto by transmitting command messages over the data path and analyzing report messages supplied by the modems in return. Each command message is identified by a specific header. A command message intended for a remote modem (34) is intercepted by the local modem (30) and reformatted so as to obtain a supervisory message that is then transmitted at the rate of one bit per baud. A command message intended for a remote multichannel modem (48) is transmitted either by a supervisory message or in the data mode of operation.

Method and system for controlling a network of modems

This analog-to-digital converter includes a comparator (20) to which the samples X.sub.(n) of the signal to be converted, are applied. The output of the comparator controls a logic circuit (22) producing (N+1) bits to a digital-to-analog converter (24) the output of which is fed back to the input of comparator (20). The converter carries out a converting procedure through N successive approximation steps at the end of which the N most significant bits available at the output of the logic circuit (22) stand directly for the rounded-off digital value of sample X.sub.(n).

Analog-to-digital converter

This invention relates to a new clock synchronizing arrangement for use in the receiving device of a data transmission system employing PSK modulation. In PSK systems, the received signal x(t), for a given carrier angular frequency .omega..sub.c can be defined by its envelope and its phase r (t) and .phi.(t), respectively. r(t) and .phi.(t) can be expressed by:

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La Gaude, France

Daniel Pilost