This report compares predictions of groundwave propagation time with experimental values. The prediction methods included an integral equation technique that accounts for both terrain and impedance variations, a method developed by J.R. Wait that accounts for impedance variations, and Millington's or Pressey's technique that accounts for inhomogeneous impedance. Experimental incremental time-of-arrival data were acquired between eight sites along a propagation path from Search-light, NV. to Ft. Cronkhite (near San Francisco Bay). The major conclusions reached from the analysis and comparison of results are: terrain variations produce significant local and cumulative phase variations, in this case, a cumulative large increase in total secondary phase; impedance values need to be known to within less than a factor of two to be sufficient for preparing charts for navigation in restricted waterways; a priori definition of terrain variation can be performed with required accuracy - a priori definition of surface impedance values with sufficient accuracy is unlikely without supporting measurements; and a combination of predictions and measurements is required for accurate chart preparation. Predictions can be used to define appropriate measurement locations and to interpolate between measurement values. (Author)

  • Corporate Authors:

    General Electric

    Marine Turbine & Gear Engineer, 1100 Western Ave
    Lynn, MA  United States  01910

    United States Coast Guard

    2100 Second Street, SW
    Washington, DC  United States  20593
  • Authors:
    • Gambill, B
    • Schwartz, K
  • Publication Date: 1979-7

Media Info

  • Pagination: 229 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00314357
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: GE78TMP-51, USCG-D-20-80
  • Contract Numbers: DOT-CG-64810-A
  • Files: NTIS
  • Created Date: Aug 27 2002 12:00AM