August 1974 | NTIA Technical Memo OT TM 75 193
An analysis of the predicted HF station/frequency usage for the USCG SSB small craft communication system
W. M. Roberts; Garth Hill Stonehocker
Abstract: A study of the HF propagation using SSB voice communications for the U.S. Coast Guard's Automated Merchant Vessel Reporting (AMVER), voluntary weather observations n1.ETEO), and search and rescue (SAR) is presented in this paper. Charts of the Atlantic and Pacific geographical areas within 400 statute miles (640 km) of the Atlantic coast, Gulf of Mexico coast, Pacific coast, and around the Hawaiian Islands show where predicted 'communications reliability can be expected to be 85% or greater. In the first analysis, three shore stations in each geographical area are used to receive from simulated ship positions (SSP) in that area. Communication area coverage is about 66% of the Atlantic area to the Atlantic shore receiving stations and 87% of the Pacific area to the Pacific shore receiving stations. A second analysis in the study combines data from the six receiving stations into an overall system using all ship-to-shore frequency bands and all SSP's. Communication area coverage increases 2 to 9% in most periods considered for either the Atlantic or Pacific areas. However, the coverage in the Atlantic area increases about 50% for summer night periods. A more practical system utilizing the best two or three frequency bands of the analysis is proposed. Histograms showing the "first choice" use of each receiving station for night and day, winter and summer, and high and low sunspot numbers to allow station utilization planning for the AMVER-METEO-SAR network conclude the report.
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