Abstract: A local area network employs a shared control channel over which control messages between frequency agile modems for each of the user nodes of a distributed architecture-configured network are exchanged. In addition to the shared control channel, a plurality of data channel pairs is available for effecting full duplex communications between any two nodes of the network. Because all data channel assignments depend upon successful use of the control channel, a prescribed control channel contention access scheme is employed to optimize use of the control channel by all users of the network irrespective of the demand for its use. Pursuant to this scheme, each requesting node must first compare an accumulated activity measure with a traffic density threshold that is continuously optimized for the current level of control channel activity.

Abstract: An offset compensator is disclosed. The offset compensator is suitable for use with any antipodal information signal distorted by an offset voltage. The offset compensator measures the positive and negative peak amplitudes, compares the magnitudes thereof, and produces a correction voltage based on that comparison. The correction voltage has a positive sign when the magnitude of the negative peak amplitude exceeds the magnitude of the positive peak amplitude, and the correction voltage has a negative sign when the magnitude of the positive peak amplitude exceeds the magnitude of the negative peak amplitude. The magnitude of the correction voltage represents the difference between the magnitudes of the positive and negative peak amplitudes, and is added to the antipodal information signal to remove the offset voltage.

Abstract: A system and method for detecting the presence of a tone burst and identifying the frequency signals contained within the tone burst of a dual tone multifrequency system includes an arrangement for applying the tone burst to a plurality of filter circuits that are tuned to respectively different frequencies including those frequency signals of which the tone burst may be comprised. The outputs of the filter circuits are monitored and signals representative of the filter outputs are compared with a first set of reference criteria, at a prescribed interval of time after beginning the monitoring of the outputs of the filter circuits. A history profile for each of the signal outputs of the filter circuits is maintained and in order to accurately identify a valid tone pair, an analysis is made of the level signal outputs of the filter circuits.