The incidental electromagnetic radiation from an automobile that is termed ignition noise is caused by fast-rise-time (impulsive) currents that flow in the vehicle's wiring. The three major sources of these impulses are the breakdown in the distributor of the gap between the rotor and the posts, the breakdown of the spark-plug gap, and the closure of the breaker points. To suppress the ignition noise, each of these sources can be treated individually. Concepts were developed and prototypes were built and tested for incorporating simple low-pass filters directly into the spark plug (by appropriate sizing of the plug's shell and inner electrode) and into the distributor. The intent of this work was to take an individual vehicle with its noise already suppressed by the techniques used in mass production in the United States, a vehicle selected as being the quietest among a group of similarly treated vehicles, and to improve its noise suppression by 10 dB over the frequency range 30 to 500 MHz.

  • Corporate Authors:

    Stanford Research Institute

    333 Ravenswood Avenue
    Menlo Park, CA  United States  94025

    Federal Communications Commission

    Washington, DC  United States 
  • Authors:
    • Shepherd, R A
    • Gaddle, J C
    • Nielson, D L
  • Publication Date: 1975-1

Media Info

  • Pagination: 160 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00091048
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: Final Rpt.
  • Contract Numbers: FCC-0072
  • Files: TRIS
  • Created Date: Jun 26 1975 12:00AM