A TV that breaks up every evening, GPS that drops out on one stretch of road, a buzz on AM radio, a hum on a ham radio, a garage door opener that stops working: radio interference has a cause, and with patient measurement you can usually find it. This guide explains the rules, the kinds of interference and their common sources, how to trace a source with simple tools and a spectrum analyzer, how to document it, and how to report it to a neighbour, your utility or the FCC.
Know the rules first
Who has to fix interference depends on which radio services are involved. In the US, the FCC's rules sort radio users into two broad groups.
Unlicensed devices: Part 15
Most consumer electronics operate under Part 15 of the FCC rules (47 CFR Part 15). That covers devices that transmit on purpose without a licence, such as Wi-Fi routers, Bluetooth gadgets, cordless phones, baby monitors, remote controls and garage door openers. It also covers devices that give off radio energy as a side effect, such as computers, LED drivers and switching power supplies. Part 15 sets two conditions on operating any of them:
- The device must not cause harmful interference. If it does, the person operating it has to stop using it until the problem is fixed, if the FCC tells them to.
- The device must accept any interference it receives, including interference that stops it working.
The second point surprises people. If your Wi-Fi or garage opener is disrupted, Part 15 gives it no protection. You can still trace and fix the source, and a neighbour may well help, but the FCC rarely acts on interference to an unlicensed device. Some other equipment, such as microwave ovens and certain lighting, falls under a separate set of rules, Part 18, which has its own limits.
Licensed services
Broadcast TV and radio, cellular networks, aviation, marine radio, public safety, GPS and other radionavigation, and amateur (ham) radio are licensed or authorised services. Interference to these is what the FCC's rules mainly protect against. "Harmful interference" in the FCC's sense means interference that endangers radionavigation or safety services, or seriously degrades, obstructs or repeatedly interrupts a radio communications service. Any device, licensed or unlicensed, that does that to a licensed service is in the wrong.
Jammers are illegal
A jammer deliberately blocks radio signals. Section 333 of the Communications Act (47 U.S.C. 333) prohibits wilful or malicious interference with licensed or authorised radio communications, and the FCC's rules prohibit marketing, selling and using jammers, including cellular, GPS and Wi-Fi jammers, except for authorised federal use. If you suspect a jammer, report it to the FCC rather than confronting anyone.
Types of interference
Knowing the mechanism tells you what to look for on a spectrum display, and what kind of fix will work.
| Type | What is happening | What you might see or hear |
|---|---|---|
| Co-channel | An unwanted signal on the same frequency as the wanted one | A second signal sitting on top of the wanted one; on a display, extra energy on exactly the same frequency |
| Adjacent-channel | A strong signal on a nearby frequency spills into the wanted channel, or the receiver can't reject it | A strong signal just beside the affected channel |
| Intermodulation | Two or more strong signals mix, in a transmitter, a receiver or corroded metalwork, and create new signals at other frequencies | Signals that appear only when two others are both on, at frequencies related to theirs |
| Desense and blocking | A very strong nearby signal overloads a receiver, so it can't hear weak wanted signals even though nothing lands on its channel | A strong signal near, but not on, the affected frequency; the problem gets worse closer to a transmitter |
| Harmonics | A transmitter also emits weaker copies at whole-number multiples of its frequency | A signal at exactly two or three times the frequency of a known transmitter |
| Broadband electrical noise | Sparking or fast switching in electrical equipment radiates energy across a wide range | A raised noise floor across many MHz; on AM, a buzz or crackle |
Two of these are about the receiver, not a faulty transmitter. Desense and blocking happen when a perfectly legal transmitter is close to a device that wasn't designed to cope with strong signals. A broadcast tower, a cell site or a neighbour's legally operated ham station can do this to a cheap TV amplifier or audio system. The fix in those cases is usually at the affected device: a filter, a ferrite choke on the cables, or a better-designed product. That is also why the FCC is unlikely to order a licensed station to stop when it is operating within its licence.
Common sources
Most interference comes from ordinary electronics nearby, very often in the same building. This table lists the usual suspects.
| Source | Typically affects | Signature | Typical clue |
|---|---|---|---|
| LED bulbs and LED drivers | AM and shortwave, VHF and UHF TV, ham radio, garage openers | Broadband noise, sometimes a series of evenly spaced peaks | Starts when the lights come on, often at dusk |
| Light dimmers | AM radio, shortwave | Buzz on AM that changes with the dimmer setting | Worse at partial brightness |
| Switching power supplies and chargers | AM, shortwave, low VHF, ham radio | Broadband noise or peaks repeating every few tens of kHz | Stops when a particular charger is unplugged |
| Solar inverters and optimisers | AM, shortwave, ham radio | Broadband noise, often with a regular pattern | Present in daylight, gone at night |
| Plasma and old TVs | Shortwave, ham radio | Broadband noise that changes with the picture | Present only while the TV is on |
| Motors with brushes | AM, shortwave, TV | Crackling noise | Matches when a drill, blender, pump or fan runs |
| Thermostats and aquarium heaters | AM, shortwave | Bursts of crackle as contacts open and close | Comes and goes on a cycle |
| Electric fences | AM, shortwave | Regular ticks, roughly once a second | Strongest along the fence line |
| Faulty power-line hardware and arcing insulators | AM, shortwave, VHF, sometimes low UHF TV | Harsh buzz with a 120 Hz rhythm; raised broadband noise | Strongest near one pole; changes with weather |
| Oscillating amplifiers and signal boosters | Cellular, GPS, TV | A strong signal or raised noise on one band | Starts after someone installs an antenna amplifier or booster |
Power-line noise has a distinctive buzz because the arc forms and stops twice in each cycle of the 60 Hz supply, giving a rhythm at 120 Hz. It is usually strongest at low frequencies such as the AM band and shortwave, and fades as you go higher. Arcing hardware often changes with the weather: some sources get worse in dry, windy conditions and others when it's wet.
Step 1: Describe the problem precisely
Before measuring anything, write down:
- What is affected: which TV channel, which radio frequency or band, GPS, a cellular service, a wireless device.
- Where: the exact address, and whether it happens in one room, the whole house, or along a street.
- When: times and days, whether it's constant or comes and goes, and how long each episode lasts.
- What it sounds or looks like: buzzing, ticking, hiss, a whistle, a pixelating picture, a dropped signal.
- What changed: new neighbours, new lights, a solar installation, roadworks, a storm, new equipment of your own.
The pattern is often the biggest clue. Interference that starts at sunset can be outdoor lighting. One that follows the weather can be power-line hardware. One that appears only in daylight can be solar equipment. One that follows a neighbour's schedule is probably their device.
Step 2: Check your own home
Start with what you control. A surprising amount of interference comes from the complainant's own house.
The battery test
If the affected device can run on batteries (a portable radio, a laptop, a handheld receiver), run it on batteries. If the problem disappears, the noise may be coming in through the device's own power supply or mains wiring, and the supply itself could be the source.
The breaker test
- Get a battery-powered radio or receiver that shows the interference clearly. For AM-band noise, a portable AM radio is ideal.
- Warn the household, and think about anything that shouldn't lose power, such as medical equipment, freezers, alarms or computers mid-task.
- Switch off the main breaker for a minute. If the interference stays, the source is outside your home. If it stops, it is inside.
- If it is inside, switch the main back on and the individual breakers off one at a time, listening each time.
- When the interference stops with one breaker off, turn it back on and unplug the items on that circuit one by one until you find the source.
Some sources run on batteries and survive a breaker test, such as a battery-backed alarm panel, a UPS, or a device charging from a power bank. If the main breaker test points inside but no single circuit does, check those.
Step 3: Sniff it out with an AM radio
A cheap battery-powered AM radio is one of the best tools for broadband electrical noise, and is widely used by utility investigators and radio amateurs for exactly this. Tune it to a quiet spot between stations, usually near the top of the dial around 1600–1700 kHz, and turn the volume up. Electrical noise shows up as a buzz, crackle or ticking.
- Walking test: carry the radio around the house, garden and street. The noise gets louder as you approach its source.
- Direction: the ferrite rod antenna inside an AM radio is directional. The noise is quietest when one end of the rod points at the source. Turn the radio slowly and note the direction of the quietest point, then take bearings from two or three places to see where they cross.
- Poles: along a street, stand near each power pole in turn. The noise is usually strongest near one pole. Note its number; utility poles usually carry an identifying tag.
- Gain down as you get close: near the source, the noise will be loud everywhere. Tune to a higher frequency, step back, or use a less sensitive radio to find the exact spot.
Never touch, climb, shake or strike a power pole, line or any utility equipment, and stay well away from fallen or low-hanging lines. Finding the general location is your job; inspecting and repairing the hardware is the utility's.
Step 4: Measure it with a spectrum analyzer
A spectrum analyzer turns "it's noisy" into evidence: the frequency, the level, the shape of the signal and when it happens. If you're new to it, start with what is a spectrum analyzer, and for setting up the receiver see HackRF One and Android setup.
Choose the right range
| Affected service | Approximate frequencies | Consentiva preset |
|---|---|---|
| AM broadcast radio | 530–1700 kHz | Full (1 MHz–6 GHz); an AM radio is often more sensitive here |
| Shortwave and HF ham bands | 3–30 MHz | Full |
| FM broadcast radio | 88–108 MHz | Common or VHF/UHF |
| VHF TV | 54–88 MHz and 174–216 MHz | VHF/UHF (Common starts at 70 MHz) |
| UHF TV | 470–608 MHz | Common or VHF/UHF |
| Garage openers and key fobs | Commonly around 300–433 MHz | Common or VHF/UHF |
| Cellular | 617 MHz–2.7 GHz and higher | Common or Cellular & Wi-Fi |
| GPS L1 | 1575.42 MHz | Common |
| Wi-Fi and Bluetooth | 2400–2483.5 MHz and 5 GHz | Common for 2.4 GHz; Cellular & Wi-Fi for 5 GHz |
The Free plan records from 30 MHz to 2.7 GHz with analysis locked. Standard covers up to 2.7 GHz and Full up to 6 GHz and down to 1 MHz. The HackRF One tunes down to 1 MHz, but its sensitivity near the bottom of its range is limited, so for AM-band power-line noise a portable AM radio is often the more sensitive sniffer. The analyzer is still useful there for timing and for documenting what you found. See the plans page for details.
Baseline versus problem recordings
- Record a baseline when everything works, at the spot where you notice the problem, for at least several minutes. Add a voice mark: "baseline, TV fine".
- Record again while the problem is happening, at the same spot, with the same preset, antenna and gain settings. Add a voice mark describing the symptom: "TV channel pixelating now".
- Compare. Look for what's new: a steady carrier (one narrow signal), broadband noise (a raised floor across a wide range, typical of electrical noise), evenly spaced peaks (typical of a switching supply or LED driver), or bursts at regular intervals.
- Check the affected frequency. Is the new energy on the affected channel (co-channel), beside it (adjacent or blocking), or spread across everything (broadband)?
Consentiva records every sweep with time and GPS, learns a baseline for each block of about 150 metres separately for night, morning, afternoon and evening, and flags signals stronger than the baseline as "unusual". One caution: if the interference has been happening every evening for weeks while you recorded, it can become part of that block's evening baseline. Compare against a different time of day, or a neighbouring block where the problem doesn't occur, as well as against the flags.
Levels are in uncalibrated dBFS unless you enter a calibration offset. That is fine for comparisons: "the noise floor across 470–608 MHz rose by 15 dB when the porch lights came on" is meaningful even without calibration. Keep settings fixed between recordings so comparisons hold. For the units, see RF units explained.
Leave it recording
Intermittent problems need long recordings. Start a walk, leave the phone and receiver in place, and let it record across the hours when the problem comes and goes. Note the moments you see symptoms with voice marks. Afterwards you can line up symptoms with what the spectrum showed.
Reading the shapes
Each kind of source leaves a recognisable shape on the display. Matching the shape to the table below narrows the list of suspects before you walk anywhere.
| Shape on the display | Likely cause | Next check |
|---|---|---|
| The whole floor lifts across tens or hundreds of MHz, with no clear peak | Broadband electrical noise: arcing, motors, some lighting | AM radio sniff; breaker test; walk towards the strongest point |
| A comb of evenly spaced peaks, sometimes drifting slowly | A switching power supply, LED driver or inverter | Unplug chargers and supplies one at a time; check lighting circuits |
| One narrow, steady line on or beside the affected channel | A transmitter or an oscillating amplifier | Note the exact frequency; take bearings; look for recently installed amplifiers or boosters |
| A narrow line at exactly two or three times a known transmitter's frequency | A harmonic of that transmitter | Check whether it comes and goes with that transmitter |
| A signal that appears only when two other strong signals are both present | Intermodulation | Note both parent frequencies and when each is on |
| A strong signal near, but not on, the affected frequency, and symptoms worse close to it | Desense or blocking of the affected receiver | Try a filter or ferrite at the affected device; move its antenna |
| Regular short bursts | A device transmitting on a schedule, or a pulsing source such as an electric fence | Measure the interval and compare it with the symptom's rhythm |
A useful habit is to look a little above and below the affected frequency too. Broadband noise affects a wide range evenly, while a single offending transmitter leaves the neighbouring frequencies untouched. That one observation often separates "electrical noise from something" from "a specific transmitter".
Step 5: Find the direction
Once you know the frequency, you can track the source down.
- Walk it. Carry the receiver around and watch the level. It generally rises as you get closer. Consentiva's GPS-tagged sweeps show where on the walk it was strongest. Reflections from buildings can cause local peaks, so look at the overall trend, not one reading.
- Body shadowing. At UHF and above, your body blocks a useful amount of signal. Hold the receiver close to your chest and turn slowly in a full circle. The level drops most when your body is between the antenna and the source, so the source is roughly behind you at the lowest reading. It is rough, but quick and free.
- Directional antenna. A directional antenna such as a Yagi or log-periodic, connected to the HackRF in place of the standard whip, gives much clearer bearings. Point it, turn slowly, and note the direction of the strongest reading. Take bearings from several places and see where they cross.
- Get closer, reduce sensitivity. Near the source, the signal is strong in every direction. Reduce gain, add attenuation, or move to a less sensitive antenna to pinpoint it, and keep well within the receiver's maximum input (−5 dBm for a HackRF, per its maker).
For tips on walking surveys, see how to survey radio signals.
Step 6: Keep a time correlation log
A log ties symptoms to measurements and to things that happen around you. It is the core of a good complaint. Keep one entry for each episode, and include times when things are fine too.
| Date and time | Location | Symptom | Frequency or service | Measured change | Conditions and events | Recording or mark |
|---|---|---|---|---|---|---|
| Mon 3 Nov, 18:42 | Living room | TV ch. 27 pixelating | UHF TV, about 548–554 MHz | Noise floor up about 12 dB vs afternoon | Porch lights next door came on 18:40 | Walk 14, mark "pixelating" |
| Mon 3 Nov, 23:05 | Living room | TV fine | UHF TV | Back to normal | Porch lights off | Walk 14, mark "TV fine" |
| Tue 4 Nov, 18:38 | Living room | Pixelating again | UHF TV | Same rise | Porch lights on; dry evening | Walk 15 |
Use the same columns every time, so a reader can scan down and see the pattern. The example entries above are illustrations of the format, not real measurements.
Step 7: Talk to the source
Neighbours
If the trail leads to a neighbour's house, a friendly conversation with your measurements in hand solves most cases. Most people have no idea their new lights or charger cause a problem, and many devices can be fixed cheaply by replacing a bulb or power supply with a better one. Some tips:
- Lead with the problem, not the blame: "my TV breaks up every evening, and I think it may be connected to some lighting; could we try something?"
- Suggest a simple test: switch the suspect device off for five minutes while you watch the symptom.
- Offer to help with the fix, such as trying a different brand of bulb.
- Keep notes of what you agreed, and keep logging.
Remember Part 15: if the problem is interference to your Wi-Fi or another unlicensed device, your neighbour has no formal duty to fix it, so goodwill is your main tool.
Your electric utility
Power-line noise is the utility's to fix. In most of Miami-Dade the electric utility is FPL. Contact their customer service, through the channels on your bill or their website, and report radio interference from their lines. Give them:
- the pole number or nearest address where the noise is strongest;
- the times it happens and how it changes with weather;
- what you've ruled out, including the main breaker test showing it isn't from your home;
- your measurements and log, if they want them.
Keep a note of any reference number, who you spoke to and when. If the problem is interfering with a licensed service and isn't resolved after a reasonable time, that history supports an FCC complaint.
Step 8: File an FCC complaint
For interference to licensed services, or for suspected jamming, file a complaint with the FCC Consumer Complaint Center. For interference to public-safety communications, the FCC Operations Center takes reports around the clock; public-safety agencies usually report through their own channels. General information on interference is on fcc.gov.
Assemble your evidence
- A one-paragraph summary at the top: what is affected, where, since when, and your suspected source.
- Your log, using the same columns throughout, including times when things were fine.
- A baseline and a problem recording from the same spot with the same settings, with the times marked.
- Your direction-finding results: the walk that shows where the level peaked, bearings, or the pole number.
- Photos or video of the symptom (the pixelating picture, the receiver display) and of the suspected source, taken without trespassing.
- Correspondence: dates of conversations with neighbours, the utility or your carrier, and any reference numbers.
Keep the originals unchanged and work from copies. An evidence package that can be checked for alteration carries more weight than screenshots alone.
What to include
- Your contact details and the location: street address and GPS coordinates.
- The affected service: the TV channel, radio frequency, GPS, cellular service or licensed station involved, and whether you hold a licence (for example an amateur call sign).
- Dates and times, and whether it is constant or intermittent. Summarise the log.
- What you've done: battery and breaker tests, conversations with the neighbour or utility, reference numbers.
- Your measurements: the frequency range, how far above the normal level it was, the type (carrier, broadband, bursts), and where it was strongest, including bearings or the pole number.
- Your suspected source, if you have one, and why: "the noise stops when the device is switched off".
Keep it factual and short. Attach or offer the supporting material. Consentiva's walk report and evidence package give you dated measurements with GPS, your voice marks, and a SHA-256 hash chain that shows the record wasn't altered afterwards. On paid plans you can add video clips with time, GPS and the RF reading burned into the image, which is a clear way to show a symptom and the signal at the same moment. See reading a Consentiva report and the sample report.
An example of a clear complaint
Here is the kind of wording that works, based on the TV scenario later in this guide. The details are illustrative; use your own.
"Since early October, over-the-air TV channels in the 470–608 MHz UHF band pixelate and freeze at my home at [address, coordinates] every evening from about sunset until about 11 pm. Reception is normal at other times. With my main breaker off, the problem continues, so the source is outside my home. Recordings made at the same spot with the same settings show the noise floor across much of the UHF TV band about 12 dB higher in the evening than in the afternoon. Walking with the receiver, the rise is strongest at the boundary with [neighbouring address], where outdoor lights switch on at dusk. I spoke to the neighbour on [date]; the problem continues. My log of 14 evenings, recordings and a tamper-evident evidence package are available."
It names the service and frequency, the place, the timing, what was ruled out, a measured change, the suspected source and the steps already taken, in under 150 words.
How time, weather and season change the picture
Interference that comes and goes can make you doubt your own observations. Patterns are normal, and they are evidence in themselves.
- Time of day. Lighting starts at dusk, solar equipment runs in daylight, and many household devices follow people's routines. Record at the same times on several days so you can show the pattern repeats.
- Weather. Power-line arcing changes with humidity, rain and wind. Note the weather in every log entry, even when it seems irrelevant.
- Signal conditions. Distant stations and noise can travel further at night, especially on AM and shortwave, and some weather conditions carry VHF and UHF signals further than usual. A distant station breaking through on a few evenings is not a local fault. Compare with a neighbour's reception if you can.
- Season. Air conditioning, pool pumps, holiday lighting and irrigation controllers all switch on at particular times of year. A problem that started in a particular month may point to equipment used in that season.
Consentiva's separate night, morning, afternoon and evening baselines help here, because each recording is compared with what is normal for that block at that time of day rather than with a single average.
Special cases
Amateur radio
Ham operators are among the most common complainants, because they listen to weak signals on bands where household noise is strongest. Amateur radio is licensed under Part 97 of the FCC rules. The ARRL, the national association for amateur radio in the US, publishes detailed guidance on finding and fixing interference, and many local clubs have members experienced in tracking noise. If you are a licensed operator, mention your call sign in a complaint. The reverse case also happens: a neighbour's TV or audio system picks up a legal ham station nearby. That is usually a receiver immunity problem, and ferrite chokes or filters on the affected device often fix it.
GPS interference
GPS signals arrive from satellites at very low power, so they are easy to drown out. A local GPS problem that affects several receivers in one place, while others nearby work, may be interference. Possible causes include illegal jammers in vehicles, faulty or oscillating antenna amplifiers and signal boosters, and some electronics. On a spectrum display, look for raised energy around 1575.42 MHz compared with a recording from somewhere unaffected. Note the place, time and whether the problem moves, which can suggest a vehicle-mounted source. Report suspected GPS jamming to the FCC.
Cellular and boosters
A badly installed or faulty cellular signal booster can oscillate and radiate a strong signal that disrupts the network for everyone nearby. Carriers take this seriously. If your phone service dropped after a neighbour installed a booster, or a recording shows a strong new signal on a cellular band, mention it to your carrier as well as to the FCC. For background on the cellular bands, see 5G frequency bands explained.
Fixes you can try at the affected device
When the source can't be changed, or when the problem is the receiver's own poor immunity, these often help. Try one at a time and record before and after, so you know what worked.
- Ferrite chokes. Clip-on ferrite cores on power, antenna, speaker and network cables reduce unwanted radio energy travelling along them. They are cheap and work best close to the affected device, sometimes with the cable looped through several times.
- Move or improve the antenna. For TV, an outdoor or loft antenna away from household electronics usually picks up much less local noise than an indoor one beside the TV. Raising it, moving it to the other side of the house, or turning it can make a large difference.
- Use good cable and connectors. Poorly screened or damaged coaxial cable, and loose connectors, let noise in. Replace suspect cables before buying anything more complicated.
- Remove unnecessary amplifiers. An amplifier boosts noise as well as the wanted signal, and a strong nearby signal can overload it. If the signal is good enough without the amplifier, try without it. A faulty amplifier can also become a source itself.
- Add a filter. A filter that passes the wanted band and rejects the strong signal causing blocking can cure desense. Choose one designed for the specific bands involved.
- Replace the offending item at home. Swapping a noisy charger, power supply or bulb for a different model is often the quickest fix of all.
Four scenarios, worked through
The TV pixelates at dusk
Your over-the-air TV is fine in the afternoon, but from about sunset several UHF channels pixelate and freeze. Your log shows it starts within minutes of dusk every day, and stops around 11 pm. The main breaker test changes nothing, so the source isn't in your home. A baseline recording in the afternoon and a problem recording at 7 pm, same spot and settings, show the noise floor across much of the UHF TV range raised in the evening. Walking with the receiver, the rise is strongest near the fence by the next house, where a new set of outdoor LED lights comes on at dusk on a timer. You show your neighbour the two recordings and ask if they'd switch the lights off for five minutes while you watch the TV. The picture clears. They swap the bulbs for a different brand, and the problem goes. If they hadn't, interference to broadcast TV is a licensed service, so your log and recordings would support an FCC complaint.
A buzz on AM near a pole
Your AM radio has a harsh buzz, worse on dry, windy days. The breaker test shows it isn't from your home. With a portable AM radio tuned between stations near the top of the dial, you walk the street. The buzz is loud for several houses, then strongest under one pole, and turning the radio gives quiet points that line up on that pole from two directions. You note the pole tag and the times and weather, record the area with Consentiva using voice marks such as "pole by number 42, loud buzz", and report it to FPL customer service with the pole number and your log. You don't touch the pole. If it isn't resolved, the reference number and log support a complaint to the FCC.
The garage door opener stops working
Your remote only works when you are right next to the door. Fresh batteries make no difference. A common cause is an LED bulb fitted in the opener's own light socket, which can produce noise near the remote's frequency. You remove the bulb and the remote works from the street again. If that hadn't helped, a recording near the opener with the remote held down would show the remote's signal; a raised noise floor or a strong signal near it when the remote fails would point to a nearby source. Remember that the opener is a Part 15 device that must accept interference, so the fix is up to you: a different bulb, a model labelled for use with openers, or moving the source.
GPS drops out on one stretch of road
Your car's navigation loses its position on the same few hundred metres of road, on some days but not others. Your phone's map loses it in the same place. Two different receivers failing in one spot suggests a local cause rather than a fault in either device. You make Consentiva recordings along that stretch with the Common preset on several days, marking with your voice where the dropout starts and stops. On a bad day, the recording shows raised energy around 1575.42 MHz along that stretch, compared with the same stretch on a good day and with nearby roads. Because the problem moves around a little from day to day, a vehicle-mounted jammer is one possibility. You don't try to identify a particular vehicle. You file an FCC complaint with the dates, times, the stretch of road, both recordings and your log.
Common mistakes
- Skipping your own home. Many complaints end when the complainant finds their own charger or bulb.
- Changing settings between recordings. A different gain, antenna or preset makes the baseline and problem recordings impossible to compare.
- Recording only when it's bad. Without a baseline, you can't show what changed.
- Short recordings of an intermittent problem. Leave it recording across the hours it comes and goes.
- Overloading the receiver. Very close to a strong source, an 8-bit receiver can create false signals. Back off or reduce gain.
- Blaming the nearest antenna. A cell site or ham station operating legally is rarely the cause, and blocking at the affected device is fixed at the device.
- Expecting the FCC to fix Wi-Fi interference. Under Part 15, unlicensed devices must accept interference.
- Touching utility equipment. Never do it. Report the pole and let the utility inspect it.
- Confrontation. An angry neighbour is much less likely to help. Lead with the problem and a simple test.
- Vague complaints. "My TV is bad" gets less attention than dates, times, a frequency, a location and a clear test result.
Glossary
- Part 15: the FCC rules for unlicensed radio devices and unintentional emitters. They must not cause harmful interference and must accept interference.
- Licensed service: a radio service operating under an FCC licence or authorisation, such as broadcasting, cellular, aviation, public safety or amateur radio.
- Harmful interference: interference that endangers safety or radionavigation services, or seriously degrades, obstructs or repeatedly interrupts radio communications.
- Carrier: a steady, narrow radio signal.
- Noise floor: the background level of radio energy when no wanted signal is present. Electrical noise raises it.
- Broadband noise: unwanted energy spread over a wide range of frequencies.
- Intermodulation: new signals created when two or more strong signals mix.
- Desense: loss of sensitivity in a receiver caused by a strong nearby signal.
- Harmonic: an unwanted copy of a signal at a whole-number multiple of its frequency.
- Ferrite choke: a ring or clip-on core of magnetic material that reduces unwanted radio energy on a cable.
- Body shadowing: using your body to block a signal so you can tell which direction it comes from.
- Bearing: the direction from you to a source, taken from several places to locate it.
- dBFS: decibels relative to the receiver's full scale. An uncalibrated level, useful for comparing recordings.
- Jammer: a device that deliberately blocks radio signals. Illegal to operate, market or sell in the US.
Common questions
Does the FCC investigate interference to Wi-Fi?
Usually not. Wi-Fi and other unlicensed devices operate under Part 15 of the FCC rules, which says they must not cause harmful interference and must accept interference they receive. The FCC prioritises interference to licensed services such as public safety, aviation, broadcasting and cellular networks.
What causes most household radio interference?
Common culprits are LED bulbs and dimmers, switching power supplies and chargers, solar inverters and optimisers, plasma and old TVs, motors, aquarium heaters, electric fences and faulty power-line hardware. Switching circuit breakers off one at a time is a quick way to find a source inside the home.
How do I find power-line noise?
Tune a battery-powered AM radio to a quiet spot between stations, usually near the top of the dial, and listen for a harsh buzz. Walk or drive along the lines; the buzz gets louder as you approach the source, and you can give the pole number or address to your electric utility.
Who do I contact about power-line interference in Miami-Dade?
Your electric utility, which in most of Miami-Dade is FPL. Contact their customer service, describe the noise and give the pole number or address where it is strongest and the times it happens.
How do I file an interference complaint with the FCC?
Use the FCC Consumer Complaint Center at consumercomplaints.fcc.gov. Include the location, the affected service or frequency, dates and times, what you have ruled out, and your measurements.
Are signal jammers legal?
No. Federal law prohibits operating, marketing or selling jammers in the US, including cellular, GPS and Wi-Fi jammers, except for authorised federal use. The FCC can impose large fines.
Can a spectrum analyzer prove where interference comes from?
It can show the frequency, level, timing and the place where the signal is strongest, which is strong evidence. Pinning it to one device usually takes a confirming test, such as the interference stopping when that device is switched off.