COMMUNICATIONS SYSTEM

摘要

A telemetry and control system is disclosed which allows a control office to communicate with a plurality of remote field stations over a preferably duplex communication channel. Transmissions, both controls and indications are formatted as messages comprising a number of words. The first word comprises the address of a selected field station to which the controls are, or have been, directed. A variable number of control words or indications and a check word or words conclude the message. At the selected field station when the address is recognized the transmitted controls are stored in a first memory means in substantial time synchronism with the reception. When the entire message has been received checking apparatus indicates whether the received data is reliable. The checking apparatus relies on a polynomial check although parity, framing and over-run checks may also be taken into account.