In the period until satellite systems provide a global and universally usable distress system for ships, a method of linking the 500 kHz morse system and the 2182 kHz telephony system is proposed. Basically it is proposed to restrict 500 kHz and 2182 kHz to distress emergency and safety messages only, with 512 kHz as the MF morse calling frequency and with 2170.5 and 2191.0 kHz on either side of 2182 kHz as telephony calling frequencies. On 500 kHz and 2182 kHz the present telephony alarm signal comprising 1300 and 2200 Hz modulation would be used for distress call, which in the case of 500 kHz would be superimposed on the present 12 dash alarm signal. For the subsequent distress message on 500 kHz a 1300 Hz modulation would be used, while in both morse and telephony cases any urgent navigation warnings would be preceeded by a burst of 2200 Hz modulation. By adopting these proposals, existing 500 kHz auto alarm arrangements would work as at present, but a loudspeaker watch on bridge or in the radio room could be easily arranged. Similarly, existing telephony 2182 kHz watch arrangements would work as at present. However, by using a watch receiver with a 500 kHz intermediate frequency, a telephony ship could also hear 500 kHz distress calls with the present 500 kHz altering signal coming in as a distinctive aural signal indicating a distress call from a telegraphy ship even if a filtered loudspeaker system were used. The proposed system eventually lends itself to the design of automatic alarm signal selector units usable on telegraphy or telephony ships and which would be considerably better than present units as regards discrimination against false calls on 500 kHz and which would also work on 2182 kHz alarm signals. The solution has the advantage of costing little to both ship and coast station operators.

  • Supplemental Notes:
    • Presented at the April 25-27, 1973 Seattle RTCM Assembly Meeting. Volume 1--Papers A thru E, Maritime Satellite Telecommunications Activity; Volume 2--Papers F thru L, Maritime Antennas, Personnel, and ITU Conference Activity; Volume 3--Papers M thru R, Systems Approaches to Maritime Telecommunications; Volume 4--Papers S thru Y, Navigation and Position Fixing in Maritime Telecommunications. Sold only as a complete four volume set--$10.00 per set.
  • Corporate Authors:

    Radio Technical Commission for Marine Services

    /Federal Communications Commission
    Washington, DC  United States  20554
  • Authors:
    • Champion, R F
  • Publication Date: 1973-4

Media Info

  • Pagination: 6 p.
  • Serial:
    • Volume: 2

Subject/Index Terms

Filing Info

  • Accession Number: 00050258
  • Record Type: Publication
  • Source Agency: Radio Technical Commission for Marine Services
  • Report/Paper Numbers: Paper 102-73/DO-71
  • Files: TRIS
  • Created Date: Nov 14 1973 12:00AM