A survey of the radiation characteristics (spectrum signatures) of electrical and electronic equipments (such as rectifiers, welders, power lines, switching devices, ignition systems, induction heaters, and electric motors). Equipment signatures compiled from interference reports indicate that some industrial activities radiate strongly enough to cause interference, and to be detected and identified, at ranges up to a few miles. Most of the energy is concentrated in the low-frequency portion of the spectrum. The equipments were measured at Douglas Aircraft Company in Santa Monica, using Stoddart Aircraft Radio Company receivers. The graphs show strong and unique signatures in the 30 to 3000 bands.
Myers, H. A., Industrial Equipment Spectrum Signatures. Santa Monica, CA: RAND Corporation, 1961. https://www.rand.org/pubs/research_memoranda/RM2764.html. Also available in print form.
Myers, H. A., Industrial Equipment Spectrum Signatures, Santa Monica, Calif.: RAND Corporation, RM-2764, 1961. As of October 06, 2021: https://www.rand.org/pubs/research_memoranda/RM2764.html