IMPROVED SUPPRESSION OF RADIATION FROM AUTOMOBILES USED BY THE GENERAL PUBLIC
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.
Stanford Research Institute333 Ravenswood Avenue
Menlo Park, CA United States 94025
Federal Communications CommissionWashington, DC United States
- Shepherd, R A
- Gaddle, J C
- Nielson, D L
- Publication Date: 1975-1
- Pagination: 160 p.
- TRT Terms: Automobiles; Electromagnetic radiation; Electromagnets; Ignition systems; Noise; Noise (Communications); Noise control; Radio waves; Ultrahigh frequency; Vehicle power plants; Very high frequency
- Uncontrolled Terms: Noise reduction
- Old TRIS Terms: Automobile engines; Electromagnetic noise; Retarding; Ultrahigh frequencies
- Subject Areas: Environment; Highways; Safety and Human Factors; Vehicles and Equipment;
- 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