Patents Assigned to General DataComm
  • Patent number: 4095045
    Abstract: A method and apparatus are disclosed for using a specified pattern of signal events for signaling in a digital communication system. Illustratively, detection of a first event in a control signal activates timing apparatus which looks for a second event in a control signal within a specified time "window" and at least one additional event in either a data or a control signal within a specified time period. Preferably, the first event is a drop in one of the carrier detect or request to send signals and the second event is a rise in the same signal. The additional event illustratively is reception of two identical data characters, each representing an address and an operation code. Each of these two characters must be received and compared for verification within the specified time period in order to produce an output control signal decoded from the operation code.
    Type: Grant
    Filed: January 19, 1977
    Date of Patent: June 13, 1978
    Assignee: General DataComm Industries, Inc.
    Inventors: Charles P. Johnson, Frederick A. Lucas
  • Patent number: 4039751
    Abstract: A method and apparatus are disclosed for closed loop testing of first and second modulators and demodulators from the modulated signal side of the first modulator and first demodulator. During ordinary communication, the first modulator and second demodulator are connected in series and the first demodulator and the second modulator are connected in series. In response to each test initiate signal, a loop is established between the second modulator and the second demodulator on their modulated signal side. Upon reception of some test initiate signals, a loop is established between the first modulator and first demodulator on their demodulated side and they are disconnected from the second demodulator and second modulator.
    Type: Grant
    Filed: March 22, 1976
    Date of Patent: August 2, 1977
    Assignee: General Datacomm Industries, Inc.
    Inventors: Robert A. Couturier, Steven J. Davis, G. Howard Robbins
  • Patent number: 3952163
    Abstract: A data communication system is described in which dial access control signals such as RING, DATA SET READY, DATA TERMINAL READY, CARRIER DETECT, and OUT OF SERVICE are transmitted between a central processing unit (CPU) and remote terminals in the form of frequency-modulated signals. A special frequency signal is transmitted from a remote terminal whenever a RING or DATA SET READY control signal is present and a CARRIER DETECT signal is not. Preferably, this special frequency is midway between the center frequency used for data communication and the frequency of either the MARK or the SPACE signal. Upon reception, this special frequency signal is processed in a particular fashion to generate signals comparable to the RING or DATA SET READY signals of the prior art. DATA TERMINAL READY and CARRIER DETECT control signals are transmitted as carrier signals and the OUT OF SERVICE signal is transmitted as a center frequency signal.
    Type: Grant
    Filed: March 3, 1975
    Date of Patent: April 20, 1976
    Assignee: General DataComm Industries, Inc.
    Inventors: Robert A. Couturier, Steven J. Davis, G. Howard Robbins