One method of continuous reference signal generation for synchronous longitudinal control was previously investigated, its feasibility established, and several difficulties associated with its practical implementation defined. These difficulties, encountered with signals at 3.75 MHz, were excessive attenuation and variable propagation characteristics. The former limits operation to short distances, while the latter results in unexpected and undesired changes in slot length. These difficulties can be partially alleviated by operating at a lower frequency (e.g., 450 KHz), according to the results of tests reported in the paper. The attenuation was greatly reduced, 0.25 versus 2.3 db/30.5 m (100 ft), but essentially no improvement in the variability of the propagation characteristics was noted. Operation under wet road conditions produced a significant increase in the attenuation--1.4 versus 0.25/30.5 m (100 ft)-- and resulted in nearly a 50 percent change in the slot length. This method of reference signal generation would be most practical for those dual-mode systems that use environmentally protected guiding structures. However, localized use (e.g., in merging operations) would readily be accomplished without the use of protected structures provided that environmental sensing were used to allow for compensating adjustments in the signal parameters. /Author/

  • Record URL:
  • Availability:
  • Supplemental Notes:
    • This paper appears in Dual Mode Transportation, which is a publication containing the proceedings of a conference conducted by the Transportation Research Board, May 29-31, 1974. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
  • Corporate Authors:

    Transportation Research Board (TRB)

    Washington, DC   
  • Authors:
    • Mayhan, R J
    • BAILEY, R E
  • Conference:
  • Publication Date: 1976

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00149271
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Mar 30 1977 12:00AM