This paper will address radio suppression development beginning with auto radio installations in the early 1920s. Early suppresion problems and attempts to develop meaningful corrective actions will be discussed in detail. Ongoing suppression development beyond the early 1920 era, will be traced forward to approximately 1960. Emphasis on special problems created by various radio power energy sources will be examined in terms of solutions, radio design direction, and variability of long- and short-term corrective actions. A brief discussion will center around antennas and its effects on radio suppression. The final portion of this paper will address internal and external electrical and electronic noise sources which ultimately affects basic radio suppression requirements.
SINCE THE EARLY MATING of radio receivers to automobiles in the 1920s, radio engineers have been confronted with a never ending challenge known as radio interference suppression. This problem has had an apparent exponential growth rate with the passage of time, both in terms of the number of problems and severity.
Diagnosis of early vehicles for electrical interference generation was for the most part quite simple, primarily because the magnitude of the noise was usually thousands of times larger than the incoming signal. To expand on that point, it should be noted that in 1919 very powerful radio transmissions were carried out using an aircraft engine magneto as the transmitter itself.
Noise sources in the early vehicles were limited to spark plugs, distributor points, generator, coil, and in general poor shielding and lack of chassis bonding.