Michael F Stephen

US Patent:

42766516, Jun 30, 1981

Filed:

Jan 29, 1979

Appl. No.:

6/007087

Inventors:

Stephen M. Bench - Lake Zurich IL
William R. Dirkes - Mundelein IL
James C. Secora - Hoffman Estates IL
Michael A. Stephen - Schaumburg IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H03L 706

US Classification:

375120

Abstract:

A data communication system for use in the control and monitoring of mobile stations, for example, in a bus monitoring system, from a central station over a communication channel carrying both data and voice information. Information is encoded into digital messages having a start code followed by one or more data blocks. The start code identifies the beginning of the data block that follows and enables synchronization of clock circuitry to the received data frequency. The data blocks have N digital words with M binary bits where one word is a parity word and N-1 words are data words. Each of the data words has a data portion and parity portion coded for correction of at least one error. Reliability is enhanced by a data detector which discriminates between data and noise or voice to provide an indication of the presence of data. In transmitting the digital messages, the bits of the N words in each data block are interleaved to provide protection against error bursts.