Man-Made Noise (Electromagnetic Pollution)

Some external noise/interference sources one might control or eliminate.

QRM

  • One person’s signal – another person’s noise.

Power Line Noise

  • Source: Arcing from faulty insulators, transformers, bad wiring.

  • Characteristics: Buzzing/humming, strongest at power line harmonic frequencies (60 Hz and multiples).

  • Identification: Peaks near power lines, detectable with a handheld AM radio.

  • Mitigation: Report to the utility company, use directional antennas.

Switching Power Supply Noise

  • Source: Cheap AC adapters, LED lights, solar inverters, electric fences.

  • Characteristics: Harmonic-rich broadband noise, often spaced at multiples of the switching frequency (e.g., 30–150 kHz).

  • Identification: Peaks around 50–150 kHz intervals, disappears when suspect device is unplugged.

  • Mitigation: Use better-shielded supplies, add ferrite chokes, or replace offending devices.

Industrial & Consumer Electronics Interference

  • Source: Smart meters, TVs, computer monitors, PLC (power line communication) devices.

  • Characteristics: Broad or narrowband interference, varies by device.

  • Identification: Can often be localized using an AM or SDR receiver.

  • Mitigation: Improve shielding, use RF filters, place distance between antenna and source.

Solar Panel & Inverter Noise

  • Source: Switching inverters converting DC to AC.

  • Characteristics: Continuous broadband noise, strongest at switching frequency harmonics.

  • Identification: Strongest during daylight, noise drops at night.

  • Mitigation: Use shielded inverters, add inline chokes, locate antennas away from panels.