Microprocessor data modem Patent #: 4263670
ApplicationNo. 06/752401 filed on 07/05/1985
US Classes:375/219, TRANSCEIVERS375/222, Modems (data sets)375/285, Antinoise or distortion714/800Parity bit
ExaminersPrimary: Safourek, Benedict V.
Attorney, Agent or Firm
International ClassesH04L 1/00 (20060101)
H04L 5/16 (20060101)
AbstractA modem is operated in a half-duplex mode having various elements which are trained on data and which are locked up while data is not exchanged, thereby eliminating the need for a preamble. A preamble is used if the period between successive transmissions exceeds a preselected threshold. In addition, a parity encoder is used to calculate a parity word for each transmission, said parity word being inserted in the first baud period of the next transmission. This first baud period is usually empty because data signals have not been received yet from the corresponding data transmission equipment.