Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1980-09-17
1983-02-22
Safourek, Benedict V.
Pulse or digital communications
Spread spectrum
Direct sequence
364200, 375121, 178 2R, H04L 700, H03K 117
Patent
active
043751032
ABSTRACT:
Disclosed are a method and apparatus for exchanging information between a data terminal equipment (DTE) and data circuit terminating equipment (DCE) or controller connected to the data terminal equipment over a communications line. The specific information to be exchanged is the information indicating the delay period between a request to send received at the DCE and a clear to send condition occurring sometime later in response to the request to send. This function is normally handled by separate signalling lines, but for the so-called mini interface, no clear to send communication line exists. A method and apparatus employed in the present invention utilizes the transmitter signal element timing or clock line to convey the information from the DCE to the DTE. In response to receipt at the DCE of a request to send signal from the DTE, the DCE temporarily stops the transmitter signal timing clock, thus preventing the DTE from transmitting data. When the DCE modem has established carrier frequency and has completed its synchronization routine, a clear to send condition exists and the delay inherent between a request to send and clear to send signal is over. To signal this condition without the use of a clear to send signalling line, the DCE re-enables the transmitter signal element timing clock. The clock remains enabled at all times except during the request to send/clear to send delay period.
REFERENCES:
patent: 4009336 (1977-02-01), Saliga
patent: 4156277 (1979-05-01), Seitz et al.
patent: 4160874 (1979-07-01), llinger
Proceedings of the Fourth International Conference on Computer Communication, Kyoto, pp. 675-680, "Evolution Toward a Universal Interface for Data Communications".
IEEE Transactions on Communications, vol. COM-28, No. 4, Apr. 1980, pp. 433-444, Bertine, "Physical Level Protocols".
Arneth August P.
Foshee Curtis L.
Duffield E. H.
International Business Machines Corp.
Safourek Benedict V.
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