For the control and supervision of machinery (ship-propulsion machinery is one example quoted) from a central position, variables such as pressures, temperatures, and shaft speeds can be converted into electrical signals which are sent to the respective instruments. The choice of transmission technique is governed by the need for reliability, accuracy, and tolerance of electrical interference, qualities which lead naturally to the use of some form of binary signal. One transmission technique widely used is pulse code modulation (PCM). This has a number of technical merits, but requires fairly complicated encoding and decoding equipment. The Author (of Ferranti Digital Systems) therefore proposes an alternative system employing a modified form of pulse duration modulation (PDM). This proposed system retains the inherent precision of PCM transmission, but needs only simple input and output circuits and (as with PCM) time division multiplexing can be used to transmit a large number of signals via a single pair of wires. The proposed sytem and its merits are described in some detail, and it is mentioned that, though the system is very extravagant in its use of available channel capacity, this is generally of no consequence as the capacity is usually more than sufficient.

  • Corporate Authors:

    Morgan-Grampian Limited

    30 Calderwood Street
    London SE18 6QH,   England 
  • Authors:
    • Goodall, L
  • Publication Date: 1977-4

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00165278
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Nov 23 2003 12:00AM