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Spectrum analyzer showing carriers and noise floor.

In this image, the peaks are radio communications. The debris at the bottom is the result of distant transmissions and accumulated noise from other equipment. Some is a natural occurrence but most is man made.


RF pollution is a form of electromagnetic interference that can cause problems for radio and wireless technologies. It occurs when there is an excess of radio frequency signals in the air, leading to interference among different radio signals. This interference can cause transmission errors, reduced range, and reduced data rates for wireless devices, as well as distortion of audio or video signals from broadcast sources. Just as we have a limited amount of resources on the planet, there is a limited amount of radio spectrum available. Devices that intentionally or unintentionally leak Radio Frequency energy with no usefully purpose clutter up that spectrum just as litter and other waste clutter up the land. The effect is cumulative and can be local, or worldwide depending on the frequencies involved. As we get more and more electronic devices in our lives, the emissions from them, large or small, contribute to the rising noise floor that makes it more difficult for other wireless devices to operate.

There are many causes for this:

LED (Light Emitting Diode) lights
RF interference from LED lights can be an issue for a number of systems that rely on radio frequency communication. LED lights can generate high levels of electromagnetic emissions that can interfere with radio frequency signals. This is not because of the LED itself, but because many of them are driven with pulsed power supplies which product a lot of harmonics.  This interference can cause a number of problems with electronics and systems that rely on radio frequency, including disruptions or complete interference with radio communication, television and satellite reception, Wi-Fi networks, and even navigation systems.

Solar Panels
Not really from the panels themselves since they put out DC, but from the charge controllers and regulators which use electronic switching to regulate the voltage. If these circuits are poorly designed with insufficient RF suppression the result can be radio signals leaking from the power wiring.

Cable TV
CATV systems use frequencies that overlap those used on the air. This works if those frequencies stay inside the cable system, but improperly installed connectors or improperly shielded equipment can cause the signals to leak out in to the air where they can interfere with other radio services such as, Land Mobile Radio, Aircraft, Ham Radio, and cell phones. It is very common for me to pick up cable system leaks on my radio while I am driving.

Cell phones
It is common for cell phone to interfere with audio equipment that is nearby. The popular radiation shielding cases don’t really help this as the phones will increase their power output to maintain connection with the site.

Other consumer Electronics
I have tracked interference caused by computers, and even an ultrasonic pest control device which was causing pulses on a TV channel.

Power Lines
When you hear the power buzzing or arcing on the high voltage lines, there is often an RF emission accompanying it.

Baofeng Spurious output

Baofeng UV-5R transmitting two carriers instead of one.

Unlicensed or uncertified radio transmitters
For many parts of the spectrum a license is required, and frequency space is assigned. In license free areas, the radios used must be certified for the use to ensure they are operating correctly. Type acceptance is done by FCC certified testing labs. For most services the setup is done by qualified technicians and the end user is not able to change the more advanced settings of the radio. The exception to this would be amateur radio where the licensed operator is responsible for the proper operation of their radio. Unfortunately this precaution gets bypassed in many ways. CB radios are supposed to be limited to 4 watts, but it is common for them to use improperly tuned amplifiers. A company named Retevis has been selling radios programed to amateur frequencies without advising the buyer that a license is required for use or what the restrictions are on amateur frequencies. A company named Baofeng makes radios that are user programmable to frequencies that they were not certified for. These radios are also known for having spurious emissions as will a lot of equipment that is improperly used. Spurious emissions are signals outside the intended frequency and can be caused by insufficient filtration, over driving an amplifier or the mix products of oscillators in equipment not designed for the frequency it is being used on. There is also deliberate misuse of radio frequencies by those that feel they should just be able to pick any frequency they want. This frequently means they are transmitting on top of someone else who was licensed for the frequency.

Nearby high power transmitters
You may get interference from transmitters that are in close proximity. Radios or TV stations, an amateur radio transmitter, or other commercial transmitter. It is important to note two things. First, they are likely licensed to transmit and a lot of consumer equipment has the warning “must not cause, and must accept any interference.”. The other is that just because you see an antenna, that does not mean that it is the cause of the problem. It may take a technician to identify the actual cause.

What can be done?
1. Avoid getting cheap, poorly manufactured equipment. Look for an FCC certification, it is not a guarantee there won’t be a problem, but it helps.
2. Identify noise sources in your house. If you have an interference problem, disconnecting and unplugging equipment until the problem stops may help identify the source.
3. Use ferrite beads, suppression capacitors and filters. The last two  probably need to be done by a technician.
4. Make sure equipment you own is used properly. Don’t contribute to the problem.
5. Get a technician to track down the source of the problem


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