do radio waves travel better at night

Why do you hear some radio stations better at night than in the day?

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Radio waves naturally travel in straight lines, so you would naturally expect (because of the curvature of the earth) that no radio station would transmit farther than 30 or 40 miles. And that is exactly the case for ground-based (as opposed to satellite) TV transmissions. The curvature of the earth prevents ground-based TV transmissions from going much further than 40 miles (64 km).

Certain radio stations, however, especially the short-wave and AM bands, can travel much farther. Short-wave can circle the globe, and AM stations transmit hundreds of miles at night. This extended transmission is possible is because of the ionosphere -- one of the layers of the atmosphere. It is called the ionosphere because when the sun's rays hit this layer, many of the atoms there lose electrons and turn into ions.

As it turns out, the ionosphere reflects certain frequencies of radio waves. So the waves bounce between the ground and the ionosphere and make their way around the planet. The composition of the ionosphere at night is different than during the day because of the presence or absence of the sun. You can pick up some radio stations better at night because the reflection characteristics of the ionosphere are better at night.

Here are some interesting links:

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Frequently Answered Questions

What causes poor am radio reception, why is am radio reception better at night.

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Why Do Radio Signals Travel Farther at Night than in the Day?

The ionosphere is a layer of the upper atmosphere about 50 to 600 miles above sea level. It gets its name because it is ionized consistently by solar and cosmic radiation. In very simple terms, X-ray, ultraviolet, and shorter wavelengths of radiation given off by the Sun (and from other cosmic sources) release electrons in this layer of the atmosphere when these particular photons are absorbed by molecules. Because the density of molecules and atoms is quite low in the ionosphere (particularly in the upper layers), it allows free electrons to exist in this way for a short period of time before ultimately recombining. Lower in the atmosphere, where the density of molecules is greater, this recombination happens much faster.

What does this have to do with radio waves? Without interference, radio waves travel in a straight line from the broadcast source, ultimately hitting the ionosphere. What happens after is dependent on a variety of factors, notable among them being the frequency of the waves and the density of the free electrons. For AM waves, given the right conditions, they will essentially bounce back and forth between the ground and the ionosphere, propagating the signal farther and farther. So clearly the ionosphere can potentially play an important part in the terrestrial radio process. But it is the constantly shifting nature of the ionosphere that makes things really interesting. And for that, we’ll have to get a little more technical, though we’ll at the least spare you the math, and we’ll leave out a little of the complexity in an effort to not go full textbook on you.

When these electrons encounter a strong AM radio wave, they can potentially oscillate at the frequency of the wave, taking some of the energy from the radio wave in the process. With enough of them, as can happen in the F layer, (when the density of encountered electrons is sufficient relative to the specific signal frequency), and assuming they don’t just recombine with some ion (which is much more likely in the E and D layers in the daytime), this can very effectively refract the signal back down to Earth at sufficient strength to be picked up on your radio.

Depending on conditions, this process can potentially repeat several times with the signal bouncing down to the ground and back up. Thus, using this skywave, rather than just the normal daytime groundwave, AM radio signals can be propagated even thousands of miles.

Of course, this can become a major problem given that there are only a little over 100 allowed AM radio frequencies (restricted to keep signals interfering too much with one another), but around 5,000 AM radio stations in the United States alone. Given that at night, the signals from these stations can travel vast distances, this is just a recipe for stations interfering with one another. As a result, at night, AM stations in the United States typically reduce their power, go off the air completely until sunrise the next day, and/or possibly are required to use directional antennas, so their specific signal doesn’t interfere with other stations on the same frequency. On the other hand, FM stations don’t have to do any of this as the ionosphere doesn’t greatly affect their signals, which has the side benefit (or disadvantage, depending on your point of view) of severely limiting the range of the FM signals, which rely on groundwave propagation.

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What you’ve described is mainly for medium waves that use directional built in antennas,short waves on the other hand intrinsically work thru ionosphere and have missing intervals but they always travel large distances.There is a third type of am signal called long wave but that is reserved for sea faring vessels and requires large antennas and travels close to surface.

So the signals don’t bounce off the clouds, which hang lower at night?

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Radio 101: Why AM stations reduce power at night

Why can’t I hear my Relevant Radio ® station at nighttime? It’s a question we hear often from listeners who don’t receive as clear a signal after sunset as they do during the day. But what most listeners don’t know is that this is a result of physics and the law.

The Federal Communications Commission (FCC) oversees broadcasting and radio, TV, satellite, and cable communications in the United States. They implement and enforce laws and regulations that networks and stations must follow in order to continue broadcasting in the US.

One of those FCC regulations pertains to nighttime broadcasting. According to the FCC website:

“Most AM radio stations are required by the FCC’s rules to reduce their power or cease operating at night in order to avoid interference to other AM stations. FCC rules governing the daytime and nighttime operation of AM radio stations are a consequence of the laws of physics. Because of the way in which the relatively long wavelengths of AM radio signals interact with the ionized layers of the ionosphere miles above the earth’s surface, the propagation of AM radio waves changes drastically from daytime to nighttime. This change in AM radio propagation occurs at sunset due to radical shifts in the ionospheric layers, which persist throughout the night.”

Basically, because of the way radio waves travel at night, many Relevant Radio AM stations are require to reduce power when the sun sets in order to avoid massive interference with other stations.

The good news is that Daylight Savings Time is on the horizon—March 8 this year—meaning we’ll be gaining an extra hour of daylight. As summer approaches, the days also lengthen, giving you more time with your local Relevant Radio station at full power.

If the reduced power at nighttime affects your listening, try tuning in via these other means:

Live streaming online at relevantradio.com
Listen live on the free Relevant Radio app
Stream on a smart speaker, like an Amazon Echo or Google Home
Podcasts of any shows you missed

Now you can amaze your friends with your new knowledge! Isn’t radio broadcasting a fascinating thing?

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Is AM Radio Better at Night?

Site Owner & Radio Enthusiast

According to MediaTracks Communications , most radio listeners tune in between 7 a.m. and 6 p.m.

Although it’s unclear from the data if listenership includes AM, there might be a case for listening later in the day. Is AM better at night?

AM radio is better at night due to the landscape of the ionosphere, which changes after sunset. The signals can travel much further due to what’s known as sky-wave propagation.

Additionally, some AM stations must stop operating after dark to reduce interference, which also helps some stations come through more clearly.

Read on if you’re interested in understanding why you can more clearly hear AM radio at night versus the daytime!

Table of Contents

Why Is AM Radio Stronger at Night?

AM radio symbol against a nighttime sky with hints of orange

If you’ve tuned into AM radio after dark and noticed the station comes in much stronger and more clearly than listening by day, it’s not simply your imagination.

This is a phenomenon that’s explainable through science.

AM radio’s propensity for a better signal at night is due to the ionosphere, a layer of the planet’s atmosphere between 50 and 600 miles over the earth’s surface.

As a name like the ionosphere might conjure, this layer contains many ions.

It’s not only ions present but free electrons.

How the ions and electrons behave depends on which part of the ionosphere we’re talking about.

The upper layers, the F1 and F2 layers, have a lower atom and molecule density, encouraging free electrons to remain solo before they combine with other electrons.

In the lower layer, called the D layer, the molecules have more density and recombine rapidly.

These electrons and ions are created during the day when the sun increases the ionization rate.

They’re temporarily unpaired. The electrons in the D layer seek to combine with whatever they can, and not necessarily other electrons. Radio waves work just as well.

Radio waves are quickly absorbed when they enter the ionosphere during the day. This severely impedes their ability to travel.

So what happens to the ionosphere without the sun? It changes. Ions and electrons continue to recombine.

You can imagine the ionosphere as a crowded party and yourself as a radio wave trying to navigate the crowd.

When everyone is standing around alone, it’s a much bigger throng to contend with.

However, when people pair up, the crowd seems more navigable.

That’s how radio waves can travel further through the ionosphere after the sun goes down.

The radio waves benefit even in the F1 and F2 layers, where recombination happens more slowly. Here, they can bend or refract toward where they came from.

This entire phenomenon is known as sky-wave propagation.

The FCC’s Involvement with Stronger AM Radio Signals at Night

However, it’s not merely sky-wave propagation that improves AM signal strength after dark. The FCC also plays a role.

According to FCC rules , many AM radio stations must stop operating or reduce power when airing at night. This is designed to minimize interference.

This rule is part of the FCC’s broader frequency plan, which includes allowable frequency allocations.

You might recall from our article about whether people listen to AM radio that about 6,000 stations are spread across the airwaves as of the early 2020s.

Some can use clear channels at night but frequently employ a directional antenna.

The antenna will reduce interference when operating on the clear channel station, providing a better listening experience for all.

If an AM station cannot obtain a directional antenna or other protections to lessen the rate of interference, the FCC will only permit them to operate the station by day.

Before you tune into your favorite AM station, use the FCC’s handy tool, AM Query Broadcast Station Search .

You can search for any AM station broadcasting between 530 and 1700 kHz. You only need to know its call sign to begin searching; even a partial call sign is fine.

How Much Further Can AM Radio Signals Reach at Night?

Why the need to curtail AM radio signals by night at all? Can they really travel that much further once the sun sets?

Indeed, they can!

AM radio at night can extend hundreds of miles beyond the same signals during the day.

This can extend your radio listening experience to other parts of your state or adjoining states.

Depending on where you live, you might even be able to enjoy AM radio outside of your home country without crossing a border.

The Role of Sunspots in Improving AM Radio by Night

If you’re a ham radio enthusiast, you might have heard people in your circle get excited when sunspots are in the weather forecast.

Sunspots occur in the photosphere, a different layer from the ionosphere. They look darker than the rest of the sun due to their lowered surface temperature and higher magnetic field.

The umbra, which is the middle area, reaches temperatures of only 6,300 degrees Fahrenheit, whereas the rest of the photosphere is up to 10,000 degrees, says the National Weather Service .

They occur when magnetic flux builds up and reflect the rate of solar activity the sun experiences.

So what do sunspots have to do with AM radio?

The sun ionizes more when sunspots occur and during other high solar periods.

The better the ionization, the stronger the signal for AM radio by nightfall.

Why Is My AM Radio Signal Still Fuzzy at Night?

While AM radio signals can travel further at night, that doesn’t mean you’re always guaranteed to get a strong signal.

Let’s assess why you might hear crackles, pop, and static.

Interference

AM stations are not impervious to interference even when the moon rises.

Power lines can cause interference, as can the equipment across your home, from garage door openers to LED and fluorescent lights, washers and dryers, computers, power supplies, light switches, electric drills, and even your phone charger.

Remove yourself or your radio from the source of interference if you can and see if that improves the AM signal.

Antenna Positioning

Another thing you can do is adjust the antenna of your radio.

If you travel a lot with your radio, the antenna can loosen over time, so tighten it first.

Secondarily, straighten the antenna and see if that makes a difference.

Check the antenna base. Do you see corrosion? If so, use an anti-corrosion product or try cleaning it.

If you can’t remove it, you’ll have to replace the radio’s antenna, as corrosion contributes to how well the antenna works and, thus, how strong of a signal you get.

Reduced Power

The last possible contributor to a fuzzy AM station is that the station is forced to lower its power per FCC regulations.

If the station doesn’t operate at full power, the audio quality may not be as strong as when listening at other times.

We recommend checking the above FCC list to see if your preferred station has to reduce power at night.

If yes, that solves your problem.

If not, and the lack of audio clarity persists, try the other methods discussed in this section.

Wrapping Up

AM radio is markedly better at night due to ionosphere changes.

The rate at which molecules bond across the ionosphere increases at night, allowing radio signals to travel further, sometimes hundreds of miles further!

However, the FCC has regulations on which AM stations can broadcast and when, requiring some to have a license or other permissions to stay on the air at night if they don’t have signal-protecting devices.

The next time you go to listen to AM radio on your short-wave ham radio, do so at night. You should certainly enjoy the experience!

When my grandfather would come to visit me as a kid, we used to sit in his RV and listen to the activity on his CB radio. His nickname for me was “Charlie” and asked me what my call sign would be. I told him it’s “Wide Receiver”, as a play on receiving radio signals and also for my dream of playing a wide receiver in football at the time.

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Why AM Listening is Better at Night

If you listen to AM radio stations at night that are just impossible to pick up during the day, chances are you’re benefiting from sky-wave propagation. Propagation is just the technical word for how radio signals travel through the air. Sky-wave propagation is the specific name given to radio waves that travel through the sky. Sky-wave propagation takes place between sunset and sunrise. It’s the flip side to the ground wave propagation used to transmit during the day.

During the day, ground wave propagation is preferable because the radiation from the sun causes so much ionization that radio signals sent into the air are absorbed into the atmosphere. When atoms in the D region of the ionosphere are ionized, you end up with free electrons and ions floating around in the air. It’s kind of like trying to walk through a room filled with dancing couples. When in pairs, there’s more room to walk through, but when they’re not paired, it’s easier to get stuck in a conversation with someone. That’s kind of how the ions and electrons in the D region work. When they’re not combined they look for something else to combine with and that’s how they absorb radio waves. At night, however, once the sun begins to set, the electrons and ions in the D region recombine rapidly – leaving more room for the radio waves to travel a little farther up. Above the D region, the F1 and F2 regions are also recombining, but much more slowly than the D region. When the radio waves hit those regions of the ionosphere, they have a chance to be reflected or bent (some prefer refracted) back toward the earth.

What that means for AM radio listeners is that they’ve experienced the remarkable ability of AM radio signals to travel hundreds of miles farther than during the day. Listening to AM, and scanning the AM dial between sunrise and sunset is a fun way to discover how far a sky-wave signal can travel to reach you. During the baseball season, you can use the sky-wave to tune in some night games played in different parts of the country. In Northern California (where C. Crane is based), as in other places around the country (even up into Alaska), people use the sky-wave to listen to stations like KGO which is a 50,000 watt station located in San Francisco. If a signal reflects off the ionosphere and then bounces off the earth and then reflects off the ionosphere again, it can travel even farther than with just a single reflection. So, as you can see, sky-wave propagation makes it possible to tune in stations that you might not even know about when tuning your radio during the day.

If you ever come across a DX website, or even a shortwave radio website, where someone is really happy about intense solar activity (or lots of sun spots), it’s because more ionization during the day makes for better sky-wave propagation during the night.

If you want to make the most of sky-wave propagation, we’d suggest the CCRadio-2E . With this radio’s fine tuning capabilities you may be able to find a new station almost every night, thanks to the built-in Twin Coil Ferrite® AM Antenna. A smaller version that works great for portability would be the CC Skywave or if you want the ultimate, the CC Skywave SSB . It’s a lot more fun than you might realize, with something as simple as a radio. Here’s a sample personal station log you can use to keep track of what you hear.

We’d love to hear how far away you’ve received an AM signal from its source, and on what radio!

Happy DXing

Catch a Wave: Radio Waves and How They Work

About the Author: Andrew Schnickel

In Fall 2000, Andrew Schnickel was a Junior majoring in CECS who enjoyed running barefoot in the rain.

Introduction

You are driving down the open road, not a care in the world. It’s a sunny summer day and you have the car windows down. Everything seems almost perfect, yet something is missing. You turn on the radio, tune it to your favorite station (see Fig. 1), and instantly the car fills with sound. Suddenly, everything feels right. Radio is something most of us take for granted. Have you ever stopped to consider how a radio works? How does a radio know which station to play? What is AM, what is FM, and how are the two different? Why does FM sound better, but AM can be heard farther away? You have probably experienced a time when finding a particular radio station has been difficult. There are many factors involved in finding and receiving stations, factors such as modulation, broadcasting power, time of day, and geographical location. The key to getting the most out of your radio is to understand how radio works and how engineering has played a part in the development of a device which most of us use everyday.

Radio Basics

Am and fm differences.

Two characteristics, amplitude and frequency (see Fig. 2), mark the difference between AM and FM radio. AM stands for amplitude modulation, which means the amplitude of the radio signal is used to encode information. FM denotes frequency modulation, which uses a change in frequency to encode information. From this you can see that both AM and FM radio use modulation to encode information. “Modulation is the variation of some property of the radio carrier in a manner that conveys information” [1].

Modulation Explained

Amplitude modulation (am), frequency modulation (fm), sound quality and performance, signal strength, frequency range, interference, broadcast range.

[1] J.J. Carr. “Elements of Electronic Communications.” Reston, Virginia: Reston Publishing Company, Inc., 1978.
[2] R.S. Carson. “Radio Communications Concepts: Analog.” New York: John Wiley & Sons, 1990.
[3] Editors and Engineers The “Radio” Handbook. Los Angeles: Editors and Engineers, 1942.
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Radio stations are assigned a call sign beginning with "K" if they are west of the Mississippi River and beginning with "W" if they lie to the east.

However, there are some stations with only a 3-letter call sign, with a "K" east of the Mississippi, or a "W" on the west side.

Before 1922, three-letter call signs were arbitrary. In the 1920's, the FCC issued three-letter call signs based on slogans, such as WGN, which is owned by the Chicago Tribune, the " W orld's G reatest N ewspaper", and WLS, then owned by Sears, Roebuck, the " W orld's L argest S tore". These stations have been "grandfathered", meaning they are allowed to keep their current sign until the station's ownership changes hands.

Demonstrate that AM radio signals can travel many 100s of miles at night. The student will listen to as many radio stations as possible, obtaining the call signs and places of origin during the evening (after sunset) hours.

Access an AM radio. If a portable AM radio is not available, automobile radios will often work well. (Have the student ask a parent or guardian to help supervise them while listening to AM radio stations in an automobile. Students without a valid driver's license are not to be left alone with keys to the vehicle.)
Search for a radio signal that is not from a local station. (Most will be faint, but the reception is usually clear enough to understand.) Stations broadcasting sporting events are easy to identify.
Listen for the station identifier "call sign". The call sign is a three- or four-letter identifier beginning with the letter "W" or "K". In the U.S., stations are required to broadcast their call sign within 5 minutes of the top of the hour.
Log the call sign and location (city) of the transmission. Also note the quality of the signal. Was it loud? Soft? Fade in and out? What was broadcast: news, sports, etc.? Was there a lot of static? etc.
Search for another signal and repeat.
You can compare the students results with the list of clear channel stations. It is entirely possible that students hear broadcasts that are not local and not one of the powerful nighttime radio stations.

During the daytime, the distance the AM radio signal travels is the distance the ground wave travels, based upon the power of the transmitter. The signal also reaches the ionosphere.

The D-Layer of the ionosphere plays an interesting role. While there are no radio signals reflected off this layer, it does absorb AM radio signals. Because signals are absorbed, there is less interference between them. Therefore, more radio stations are transmitting during the daytime, and these stations can often transmit at higher power.

At night, the D-Layer disappears, and the transmitted signal can then bounce off the ionosphere and return back to the Earth. As a result, some low power stations must cease transmission at sunset, while others reduce their transmitted power to reduce interference.

However, there are high power clear channel stations that can broadcast all night. It is these stations the students will most likely find.

Building a Weather-Ready Nation

NOAA Weather Radio (NWR) is a nationwide network of radio stations broadcasting continuous weather information direct from a nearby National Weather Service office. NWR broadcasts National Weather Service warnings, watches, forecasts and other hazard information 24 hours a day.

Working with the Federal Communication Commission's (FCC) Emergency Alert System, NWR is an "all hazards" radio network, making it your single source for comprehensive weather and emergency information. NWR also broadcasts warning and post-event information for all types of hazards - both natural (such as earthquakes and volcano activity) and environmental (such as chemical releases or oil spills).

Known as the "Voice of the National Weather Service," NWR is provided as a public service by the National Oceanic & Atmospheric Administration (NOAA), part of the Department of Commerce. NWR includes more than 900 transmitters, covering all 50 states, adjacent coastal waters, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific Territories. NWR requires a special radio receiver or scanner capable of picking up the signal.

For more information, go to the NOAA weather Radio website.

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Why Do Radio Signals Travel Farther At Night Than In The Day?

The ionosphere is a layer of the upper atmosphere about 50 to 600 miles above sea level. It gets its name because it is ionised consistently by solar and cosmic radiation. In very simple terms, X-ray, ultraviolet and shorter wavelengths of radiation given off by the Sun (and from other cosmic sources) release electrons in this layer of the atmosphere when these particular photons are absorbed by molecules. Because the density of molecules and atoms is quite low in the ionosphere (particularly in the upper layers), it allows free electrons to exist in this way for a short period of time before ultimately recombining. Lower in the atmosphere, where the density of molecules is greater, this recombination happens much faster.

What does this have to do with radio waves? Without interference, radio waves travel in a straight line from the broadcast source, ultimately hitting the ionosphere. What happens after is dependent on a variety of factors, notable among them being the frequency of the waves and the density of the free electrons. For AM waves, given the right conditions, they will essentially bounce back and forth between the ground and the ionosphere, propagating the signal farther and farther. So clearly the ionosphere can potentially play an important part in the terrestrial radio process. But it is the constantly shifting nature of the ionosphere that makes things really interesting. And for that, we’ll have to get a little more technical, though we’ll at the least spare you the maths, and we’ll leave out a little of the complexity in an effort to not go full textbook on you.

In any event, the ionosphere’s composition changes most drastically at night, primarily because, of course, the Sun goes missing for a bit. Without as abundant a source of ionising rays, the D and E levels (pictured right) of the ionosphere cease to be very ionised, but the F region (particularly F2) still remains quite ionised. Further, because the atmosphere is significantly less dense here then the E and D regions, it results in more free electrons (the density of which is key here).

Of course, this can become a major problem given that there are only a little over 100 allowed AM radio frequencies (restricted to keep signals interfering too much with one another), but around 5000 AM radio stations in the United States alone. Given that at night, the signals from these stations can travel vast distances, this is just a recipe for stations interfering with one another. As a result, at night, AM stations in the United States typically reduce their power, go off the air completely until sunrise the next day, and/or possibly are required to use directional antennas, so their specific signal doesn’t interfere with other stations on the same frequency. On the other hand, FM stations don’t have to do any of this as the ionosphere doesn’t greatly affect their signals, which has the side benefit (or disadvantage, depending on your point of view) of severely limiting the range of the FM signals, which rely on groundwave propagation.

Bonus Fact:

AM Radio (Amplitude Modulation) was the first type of radio broadcasting used for mass-consumption by the public and is still widely used today. (Although AM radio is becoming less widespread in America, it is still the dominant type of terrestrial radio broadcasting in some countries, like Australia and Japan.) This type of signal works with the receiver translating and amplifying amplitude changes in a wave at a particular frequency into the sounds you hear coming from your speakers. FM Radio (Frequency Modulation), which started coming into its own in the 1950s, is broadcast in much the same way that AM is, but the receiver processes changes in the frequency of a wave, as opposed to the amplitude.

Picture: Kenji Yamamoto /Flickr

Dan Eder writes for the wildly popular interesting fact website TodayIFoundOut.com . To subscribe to Today I Found Out’s “Daily Knowledge” newsletter, click here or like them on Facebook here . You can also check ’em out on YouTube here .

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Radio Waves

Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than visible light. Humans use radio waves extensively for communications.

Black and white radio tower with clouds in Harrisonburg, VA on James Madison University's campus.

This radio tower has both rectangular and circular antennas to transmit and receive radio frequency energy.

Photo by Christina Telep on Unsplash

The wavelengths of radio waves range from a few millimeters (tenths of inches) to hundreds of kilometers (hundreds of miles). Visible light, for comparison, has wavelengths in the 400 to 700 nanometer range, about 5,000 times shorter than the shortest wavelength radio waves. Radio waves oscillate at frequencies between a few kilohertz (kHz or thousands of hertz) and a few terahertz (THz or 1012 hertz). "Far infrared" radiation borders radio waves along the electromagnetic spectrum and has slightly higher energy and shorter wavelengths than radio waves.

Microwaves are short wavelength radio waves which we use for cooking and for communication. Microwaves have wavelengths between a few millimeters and tens of centimeters (tenths of inches to tens of inches).

Various frequencies of radio waves are used for television and FM and AM radio broadcasts, military communications, mobile phones, ham radio, wireless computer networks, and numerous other communications applications.

Most radio waves pass freely through Earth's atmosphere. However, some frequencies can be reflected or absorbed by the charged particles in the ionosphere .

Electromagnetic (EM) Spectrum

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Help receiving TV and radio

Why is medium wave reception worse at night.

At night medium wave radio signals can travel much further than during the day. This means your radio is able to receive more radio channels either using the same frequency as the service you are listening to or adjacent to that frequency. The result is a higher level of interference and a deterioration in both the sound and coverage.

Why am I unable to receive Local Radio, or National Radio such as BBC Radio Scotland, on my DAB Radio?

The BBC's local and national radio services are carried on local commercial DAB Multiplexes. Please see our help page to see how DAB multiplexes work , Therefore, you may not be receiving this service, as there is not a commercial DAB service in your local area. To check what coverage of DAB services are available in your locality, please see our Transmitter checker tool .

My DAB reception has started to drop out, is this due to poor reception?

Firstly, poor reception might be down to poor coverage, so it is best to check you are in a DAB coverage area. Use our transmitter tool , which will tell you what national and local DAB services are available in your locality.

Secondly, If you are in a good coverage area, and are still receiving poor DAB reception please try our Problem Assistant for further advice.

How can weather affect DAB reception?

DAB reception is rarely disrupted by high-pressure weather conditions, but under some circumstances, signals from very distant transmitters can cause reception to break up, or be lost for periods of time. If you suspect this - particularly if you are also getting interference on FM - wait until the weather changes.

Where can I find Radio 5 Sports Extra and Radio 4 LW on DAB and when does it broadcast?

5 Sports Extra is a secondary DAB service of Radio 5 Live, and not always available on air. When the BBC has additional sports content, it can be found next to Radio 5 Live on DAB radio only. The 5 Sports Extra schedule is available online.

This is similar to Radio 4 LW on DAB, which can be found next to Radio 4 on the list of stations. Radio 4 LW broadcasts Yesterday in Parliament , along with the Daily Service each day.

For more information on finding and storing these services, see our Help guide on DAB secondary services .

Can LED Lights Interfere with my DAB Reception?

There is a possibility some LED Lights can cause interference to DAB and FM Radio Reception, particularly if LED lights are used to replace halogen lights, and retain the original transformer. This is because the power used is lower, and is forced to work outside of its normal operating parameters, resulting in electrical impulse interference. For more information on interference, please see our RTIS site

DAB Help Guides

What is a good dab installation.

Coverage and location Your radio must be in a good DAB coverage area to receive BBC services. Have a look at our Transmitter Checker to see what BBC services you can receive where you are. If you live in a basement flat, or your building is steel-framed or reinforced concrete, coverage may be affected. Tuning Most DAB radios can be tuned easily at the touch of a button. Sometimes a full scan is required. Portable radios should be tuned in a location in your home where the best possible signal is received. Most DAB radios come with built in signal strength meters which can be helpful. From time to time radios should be re-tuned in order to discover new stations. Telescopic aerials Telescopic aerials on portable radios should be fully extended to receive a good signal. Tilting and swivelling the aerial will help to get the best signal. Broken aerials may affect reception. Outdoor aerials An externally mounted aerial can be attached to many types of DAB portable radio and hi-fi systems. DAB aerials are different from FM or TV aerials, so you need a good quality DAB-specific aerial. An indoor aerial may be good enough, but for the best reception use an outdoor one. Ideally, this should be on the roof or high up on the outside of the building, though it may also give good results in the loft. Cables and Connectors If you have an external aerial, a radio signal will always lose some of its strength as it passes along the cable and through the connectors. It is important to minimise the loss by using good quality cable and connectors. DAB radio in cars DAB uses different frequencies from FM radio. We advise you check that your antenna is able to receive DAB, in the majority of cases you will need a new antenna. An exception is "helically wound" FM aerials. See our guide on DAB radio in cars Qualified Installer The BBC cannot recommend individual Installers. The CAI ( Confederation of Aerial Industries ) is a recognised trade body which will can put you in touch with one of their members in your area.

Troubleshooting DAB reception

Transmitter faults By using our Transmitter Checker , you can check which DAB radio services are available at your location. It will also show you any transmitter faults. Currently it reports on network DAB stations only; Local and Nations radio faults are not included. Works and Warnings Check whether there are any known works or warnings that might be causing the problem. Tuning DAB uses multiplexes to group services together. The BBC network stations, e.g. BBC Radio 1, BBC Radio 4 are grouped together in a single multiplex. Nations and Local radio services are carried on a mix of commercial multiplexes. Try switching your radio on and off. If you still have a problem use the ‘autotune' function to re-tune. If this does not work, a full re-scan might be needed. Check your radio manual for specific instructions on doing a full re-scan. Further information on tuning your DAB radio can be found by visiting the Get Digital site or see our DAB tuning guide . Portable Radios Ensure the telescopic/integrated aerial is fully extended. Try moving the radio around to see if you can find a better position where you get good reception of all the stations you want to listen to. In most circumstances the supplied telescopic aerial should be perfectly adequate, and as a rule of thumb DAB aerials tend to work best when vertical and extended at least 35 cm. If your radio reception is poor then you could consider an external aerial for best reception quality. Even in good areas an external aerial will guarantee optimum performance and will also ensure consistent listening quality. Many Digital radios have a signal strength display which enables you to position the Radio for the best reception (usually a number of blocks) as a guide of reception quality. Unfortunately, some radios are less sensitive than others and need careful positioning to work reliably. If your radio displays signal strength, use this as a guide to ensure the best position. Our DAB installation guide provides further information. External aerials It is important to check the cables and the aerial for damage and that they are operating correctly. Make sure any cables between your radio equipment and aerial are connected securely. For further information see our DAB installation guide . Damaged Cables Water can get into external cables and can cause reception problems. To rule this out see our guide on water damage to cables . Car Radios Radio reception can drop out when on the move due to changes in topography. See our car radio guide for more information. Weather Radio signals can be affected by fine weather including high pressure. The only solution is to wait for the weather to change, you should not re-tune during this time. Our information on h ow clear skies and fine weather can affect your radio reception may be useful, please see our weather guide. Lost reception of one or more station within a multiplex If all other stations are working ok and you have just lost one station. The problem could be due to a number of reasons, the station may have stopped broadcasting or have moved multiplexes rather than a radio fault. All of the stations in one multiplex should be behaving the same way. Interference If you are still having problems, it is possible an unwanted signal is the cause. For information on the symptoms of interference see our sister website RTIS . Qualified Installer The BBC cannot recommend individual installers. The CAI ( Confederation of Aerial Industries ) is a recognised trade body which will be able to put you in touch with one of their members in your area.

DAB radio in the car

To listen to DAB in your car you will need to ensure your aerial is able to receive a DAB signal. You may need to contact your car manufacturer to check. However, helically wound FM aerials are able to receive DAB. The best place to put a DAB aerial is on the roof of the car and as far from the engine as possible, to avoid any interference.

If your car radio is showing no signal or no service for a station you usually receive, this could be down to one of the following things: DAB Transmitter Fault If you know your location, you can use our transmitter checker to see whether there is a problem. If not, then check the radio and the aerial to confirm they are working correctly. Interference Poor DAB reception can also be caused by equipment used in the vehicle. For example, phone chargers or dash cams sometimes cause interference and affect your radio signal. Try unplugging the items to see if one of them is causing any interference. Retuning & DAB Pre-set Stations If you have bought a new car, the DAB radio may be tuned to DAB stations in a different location. Delete the presets and re-tune to the services in your area. Topography When travelling in the car, your signal can be affected by natural features of the land, for example, hills, valleys, rivers, etc. The signal should return once you move away from these features.

Part time/secondary radio services on DAB

Where can I find them?

When Radio 5 Sports Extra is on air, you should find it right next to 5 Live on the list of stations on your digital radio. The same is true for Radio 4 LW on DAB. It can be found next to Radio 4 on the list of stations. When do they broadcast? Radio 5 Sports Extra has a dynamic schedule. To see what is available when, the BBC keeps a schedule on the sport website . Radio 4 LW normally broadcasts Yesterday in Parliament, The Daily Service and the Shipping Forecast each day. How to find these services It is best to re-tune your radio when they are broadcasting, so it will store the station in its memory.

Who is responsible for my Shared/Communal Aerial?

It is worth first checking to see whether the problem is with your own equipment, or the local transmitter. If neighbours are having the same problem it may be that the aerial itself is at fault, or there may be an interfering signal. In either case, you will need to ask your landlord or management committee to solve the problem. Checking for problems Check cables and leads within your property to ensure the problem is not a simple installation fault. Please see our Freeview Installation guide for further details. To see whether there are any faults with the local transmitters use our Transmitter Checker tool. This will help you to see if there are, or have been recently, transmitter faults in your local area. Electrical interference There are differences between a reception problem and one caused by electrical interference. See our help guides which explain the differences. Our sister site, the Radio and Television Investigation Service (RTIS) also has useful information on how to distinguish the difference. If it is potentially interference, your landlord or management committee can contact the regulator, Ofcom, for help with solving the problem, using their contact web form. Since it is a communal aerial, you will not be able to contact Ofcom directly.

Freeview FAQs

Why am i receiving the wrong regional news.

Your television can sometimes receive signals from more than one transmitter, which may be transmitting different regional news. This is more likely to occur following a retune of your television. To ensure you are receiving the correct regional news programmes from the transmitter your aerial is pointing towards, you will need to do a manual retune. Please see our help guide on a manual retune.

If you are using satellite to watch TV, please see our FAQ here

If you're using cable to watch TV and are getting the wrong regional news, it is likely a technical issue and you'll need to speak to your cable provider.

For help setting the correct regional news on iPlayer, see our FAQ here

What should I do if my TV reception gets worse at night?

If you suffer from reception problems in the evening, this suggests that the signal getting to your television is not quite strong enough. Changes in the weather, temperature or atmospheric pressure can cause an already poor signal to break up or be lost.

To fix this, you will need to look at ways of improving the signal strength and quality. Once your receiving setup has been optimised (so you have a strong signal), if the signal does drop slightly in strength, your television receiver will still have enough signal to prevent the picture and sound from breaking up. We recommend you read the  Good Installation Guide  for suggestions on what to check.

It is also worth checking whether your television is tuned to the transmitter that supplies the best signal for your location. Use our Transmitter Checker Tool to see if you are in an area where more than one transmitter can be received. Then use our  guidance on performing a manual retune , which allows you to tune to the best transmitter for your location.

Get help from an Aerial Installer

If you continue to have problems, consider the use of an Aerial installer. We cannot recommend individual Installers. However, the  CAI ( Confederation of Aerial Industries )  is a recognised trade body that will be able to put you in touch with one of its members in your area.

If you are a tenant or use a communal aerial system, contact your landlord/managing agent.

Why are subtitles sometimes delayed or out of sync?

For programmes which are pre-recorded, we create the subtitles in advance. A technician uses the audio and picture to sync them with what’s happening on screen. For a programme broadcast live, (like the News), subtitles will be generated as it is broadcast, which is a complex and problematic process. This means you’ll often notice a delay when watching live programmes.

How do I turn off the voice commentary (Audio Description) happening over my picture?

This is an accessibility feature called Audio Description. How you turn off Audio Description defers slightly depending on the platform you are using. Select the platform you use for instructions:

Freesat

Freeview

Virgin Media

BBC iPlayer

For instruction on how to turn off Audio Description on BBC iPlayer, visit our FAQ - Can I remove audio description on BBC iPlayer?

If you would like to learn more, check our Audio Description help guide

Freeview Help Guides

What is a good freeview installation.

Aerials There are all kinds of aerials available on the market and some which are specific to certain frequencies. A wideband aerial is a popular choice, although there are other aerials available. A qualified aerial installer with local knowledge will be able to advise further. Height Your aerial should be as high as possible pointing towards the transmitter with the best signal. Use the our Transmitter Checker tool to determine the best transmitter for your location. Ensure there is nothing in front of the aerial that could block the signal, such as trees. All TV reception predictions assume an outside aerial at a height of 10m from the ground. Loft and indoor aerials If you live close to a transmitter or can get a strong TV signal, then it could be possible to use an aerial in your loft or an indoor portable aerial. However, in both cases the signal will be weakened as it has to pass through various obstructions such as walls, roof tiles, foil backed insulation etc. Even if you are predicted to have good reception, you may have problems receiving services using indoor or loft aerials. Cable and connectors A television signal will always lose some of its strength as it passes along the cable and through the connectors. Therefore it is important to minimise the loss by using good quality cable and connectors. Amplifier These are not recommended unless absolutely required as they can introduce unexpected reception problems. See our help guide on the different types of amplifiers available . Polarisation Depending on the transmitter you are using, your aerial elements will need to be mounted flat (horizontal) or on its side (vertical). A qualified aerial installer with local knowledge will be able to advise further. Qualified Installer We cannot recommend individual installers. However the CAI ( Confederation of Aerial Industries ) is a recognised trade body which will be able to put you in touch with one of their members in your area.

Troubleshooting your Freeview Television reception

Effects of poor Freeview reception are: loss of channels picture break up sound glitches/break up Step 1 – Check if there is a fault with your local transmitter First, use our Transmitter Checker tool. If there is a fault, it will be highlighted. If there is more than one transmitter listed, check all of them. If there is no problem with the transmitter, visit our Works & Warnings page . We advise of known issues, major transmitter work and whether high pressure or extreme weather could be causing problems. If there is an issue with your local transmitter or you’ve found the answer on a Works & Warnings page, the problem should resolve itself without you doing anything. Consider using BBC iPlayer or BBC Sounds while you wait for the issue/work to be resolved. Step 2 – Check the cabling Start by checking the cables that are connected to the television or set-top box and the wall socket. They should be securely connected. If possible, try with another cable, in case the cable or connector is faulty. Step 3 – Check your television is tuned to the transmitter with the best signal You should get the strongest signal from the transmitter your aerial is pointing towards. Some Freeview reception problems are due to the receiver not using the best signal. This can be an issue when signals from more than one transmitter can be received. A manual retune will allow you to choose which transmitter signal to tune to. The Transmitter Checker can help figure out which transmitter your aerial is pointing towards. Check our manual retune guide for instructions. Step 4 – Check the aerial system Next, you might want to consider getting your aerial installation checked. We cannot recommend individual Installers. However the CAI (Confederation of Aerial Industries ) is a recognised trade body and can put you in touch with one of their members in your area. If you are a tenant or are using a communal aerial, you should contact your landlord/managing agent. Also, please read our guides on: What is a good Freeview installation How to check your cables for water damage How to better your signal using an amplifier or attenuator Who is responsible for my Shared/Communal Aerial? Other Considerations Obstructions between the aerial and transmitter can cause problems. Trees are the most common obstructions. They can affect the signal. This can be greater at different times of the year (when there are more leaves), when wet or in high winds. Other examples of obstructions are newly built property nearby, or construction equipment, like a crane. If obstructions are too problematic to overcome and/or permanent, you might want to investigate if you can reposition your aerial and retune to a different transmitter. Another solution would be using another way of receiving services, like Freesat for example. If you suspect trees could be a problem, read our guide What is the effect of trees on reception? Interference If after working though the steps above you are still having problems, it’s possible that interference (an unwanted signal interfering with your reception) could be the cause. Please see our other help site, the Radio and Television Investigation Service for further information.

How to check your cables for water damage

If possible, check the external cable for any signs of damage, such as cracking and tears. Damaged cables can cause reception problems and can allow water into your installation.
Find the cable that goes from your aerial or satellite dish into your television, radio or set top box and unplug it. This may be from a socket on the wall or a direct cable through the wall.
If you are using a satellite dish to receive your television, you will also need to check the LNB and cap for any signs of water damage. You may need to instruct a qualified installer to assist you with this.
If it is a direct cable, check for any obvious signs of water or a green build-up on the connector. If it is from a wall socket check both the connector on the cable and on the wall socket for any signs of water or green build-up. A green build-up is a sign that water has at some point got into your installation.
If you find water damage then it is likely that the cable will need replacing by a qualified aerial installer.

We cannot recommend individual installers. However the CAI ( Confederation of Aerial Industries ) is a recognised trade body which will be able to put you in touch with one of their members in your area.

How to better my signal using an amplifier or attenuator

When to use an amplifier A signal amplifier should only be used as a last resort when the television signal is weak. Even the best amplifier will still add some noise to the television signal it is amplifying/boosting that could result in picture break up. A good amplifier should have a filter built in that only allows the signal you want to be boosted and not any unwanted signals. Otherwise, all the unwanted signals will also be boosted, which can cause pictures to break up. Problems using amplifiers Amplifiers themselves are a common source of reception problems. For example, if water were to get into a masthead type, they can start to boost the result of the fault. This could be unwanted signals and result in picture loss on your own television and, maybe, those living nearby. To check, remove the power from the amplifier and see whether the problem goes away. There are three types of amplifier – masthead, set-back and distribution. All these need a power supply to work. Masthead These fit directly under an outside aerial and usually the best type of amplifier to fix weak signals. Set-back These fit between the aerial socket in the wall and your television. Distribution These split the TV signal from a single aerial and allow the signal to be sent to several different televisions in the building.

Combined amplifiers Some amplifiers are a mix of the above. For example, some masthead amplifiers are also distribution amplifiers. Some can also combine television and FM radio signals. Attenuators When to use an Attenuator If you are experiencing pixellation or picture break up, it may be that your signal is too strong as this often presents itself similarly to a weak signal. This is likely to happen if you live close to a transmitter. Attenuators can be used to decrease the incoming signal if it is too strong without distorting it. It is effectively the opposite of an amplifier, though the two work by different methods. While an amplifier provides gain, boosts the signal, an attenuator provides loss, reduces the signal. Attenuators are always a compromise and should only be used if absolutely necessary. They come in a variety of powers; in most cases a small reduction is all that is needed. It may take a little trial and error to find the most suitable one for your installation, and it is worth taking the advice of a local aerial contractor to select the correct one for the installation.

High pressure could affect TV & Radio services across parts of the UK - 12 April 2024

Some viewers in various areas of the UK might experience periods of interference to television and radio services.

These weather conditions can move and change, which makes it difficult to know where it will hit next. If your television picture starts to break up without warning this could be the cause of the problem.

You can check if the problem is impacting your local transmitter using the transmitter checker tool. If there are no faults displayed it is possible the problem is impacting your radio or television system directly.

NOTE: At these times, there is nothing you can do but wait until the weather changes. You should not re-tune your television or radio when this happens. If you have access to BBC iPlayer or BBC Sounds , you could switch to these while you wait for the weather to change.

Still having problems following a retune?

If you have retuned your television and continue to have problems with missing channels, or reception problems, as a result of the high pressure, you'll have to retune again once the weather has cleared. We would advise visiting Freeview for help.

Cable and satellite services are not affected.

Problems with radio reception?

Radio can be affected by High Pressure. Read more here.

Matt Taylor from BBC weather explains why high pressure weather conditions can affect your Freeview television reception in the video below.

Engineering work affecting BBC radio services in Oxfordshire and surrounding area from 2 April 2024

This work will be taking place over a number of weeks in order to complete essential maintenance on the steel 'cable stays' that support the Oxford transmitter mast. It will involve operatives working in close proximity to the mast and at height, therefore it will require periods of reduced power and shutdowns to radio services for the safety of the operatives.

Are any other transmitters affected?

It will also affect a number of transmitters that receive a radio feed from Oxford. You can use our transmitter checker tool to check the status of your local transmitter .

Which radio stations will be affected?

BBC Radio 1 - 4 and BBC Radio Oxford.

All BBC National DAB services

When will this happen?

There are several pieces of work planned within the allocated dates and they will take place during daytime hours. All work is weather dependent and we would recommend using our transmitter checker tool to check if this work is currently affecting your radio reception.

Other ways to listen.

BBC Sounds - on mobiles, tablets, Smart televisions, Smart speakers.

It is also possible to listen to BBC Radio stations on your television.

Image credit: mb21

Changes to BBC Radio 4

Specific changes taking place in April 2024:

There is no longer a separate schedule for BBC Radio 4 LW. The BBC is encouraging listeners to transition to alternative platforms. The same content will be broadcast on BBC Radio 4 on FM, DAB, BBC Sounds, Digital TV. This change happened on the 1st April.

Effective 1st April, The Daily Service and extended Yesterday in Parliament programmes will be available on Radio 4 Extra on DAB, BBC Sounds and Digital TV
Effective 15th April, Radio 4 will no longer be available on medium wave. Medium wave listeners will need to retune their radio to alternative platforms.

Daily Service and the extended edition of Yesterday in Parliament are now available on BBC Radio 4 Extra on DAB, Digital TV and BBC Sounds .

Upon its return, Test Match Special will continue uninterrupted on Radio 5 Sports Extra on DAB, Digital TV and BBC Sounds .

The Shipping Forecast will continue to be broadcast on BBC Radio 4 twice a day (weekdays) and three times a day (weekends). This will be available on all platforms: FM, DAB, BBC Sounds , Digital TV.

More information can be found in this article .

Latest Freeview works and warnings

Latest radio works and warnings, essential engineering work affecting r4 lw listeners using the droitwich transmitter 9-12 april 2024.

Essential engineering work is taking place on the Droitwich transmitter that will involve a period of shutdown for up to 4 hours (10:00-16:00) between Tuesday 09 and Friday 12 April.

Platform affected BBC Radio 4 on LW.

DAB radio - use the transmitter checker tool to find availability in your area.

BBC Radio stations on your television.

Why can I hear a foreign radio station?

This normally happens in the summer months, due to high pressure weather conditions in the atmosphere, allowing radio signals to travel further. The cause is an atmospheric effect known as Sporadic-E and can last from a few seconds up to an hour or more.

For more information on how weather can affect your Radio services, please see our guide

Radio Help Guides

Troubleshooting fm radio.

B asic Installation It is important to check your installation is working properly and that your radio is in the best possible position. We have a basic installation guide to help you with this. Works and warnings Check whether there are any known works or warnings that may be causing the problem. Transmitter faults and frequencies Use our Transmitter Checker to check the transmitter is not undergoing any work and to see which FM radio services you can receive from your location. Hi-Fi radios If you are using a Hi-Fi tuner and stereo reception is hissy, but mono is fine, your aerial may not be powerful enough. You may need to consider a loft or external aerial to solve your reception problem. Weather FM radio signals can be affected by fine weather including high pressure and the only solution is to wait for the weather to change, you should not re-tune during this time. Our information on how clear skies and fine weather can affect your radio reception may be useful, please see our Weather Guide. Pirate Radio In some urban areas Pirate Radio can be a problem. The regulator, Ofcom, deals with Pirate Radio and you can report it using the Pirate Radio form on the Ofcom website. Distorted S and Z sounds (sibilance) This can happen when your radio receives more than one signal. The second signal is picked up by the radio moments after the first. For example you receive one signal directly from the transmitter and another is being reflected off a nearby hill. Try moving the radio or tuning to a different frequency. Twittering and whistling This often sounds like birds tweeting and happens if there is another frequency being transmitted near the one you are listening to. This can commonly be caused by high pressure when, during fine weather, radio signals can travel much further than normal. These signals can be both UK and foreign stations. There is nothing that can be done and the problem will go away when the weather changes. Hissing and fading This normally means that the signal you are receiving is not strong enough. See our guide on Hissing and Fading . Buzzing, clicking and pops This may mean an electrical item in your home or nearby, is interfering with the reception of your FM radio and is causing the buzzing, clicking or pops you can hear. See our guide on Buzzing and Clicking . If you are still having problems see our sister site Radio and Television Investigation Service (RTIS) for further information. Distortion - fuzzy, gritty, scratchy sound This is commonly caused by the FM signals being bounced off objects or hillsides and reaching your radio by different paths. Its technical name is multipath distortion. It is often worst in hilly or heavily built-up areas. Indoor portables are especially susceptible. Distorted sound can also occur if your radio is off-tune. This can increasingly happen if your batteries are beginning to fail. Ensure your radio is correctly tuned-in, and check that your batteries are in good condition, or use mains power. Humming If you are hearing a hum it is often linked to an issue with your mains adapter. You may need to check that all parts of your receiving system are fully earthed.

What to do If your radio is a portable, try moving the aerial to different angles. You could also try a different position in the room. Window sills and high shelves are good places for radios; avoid putting them close to radiators or electronic equipment such as computers, mobile/cordless phones or TV sets.

The telescopic aerial fitted to stereo portables is a compromise and the radio will often only give really good results if connected to an external aerial. If that’s not possible, switch to mono as it will usually sound better. Some sets do this automatically. Make sure you are tuned to the best frequency for your area, as you can often pick up more than one signal. Use our Transmitter Checker to find the best frequencies for your location. Qualified Installer The BBC cannot recommend individual installers. The CAI ( Confederation of Aerial Industries ) is a recognised trade body which can put you in touch with one of its members in your area.

Troubleshooting MW/LW Radio

Basic Installation

It is important to check your installation is working properly and that your radio is in the best possible location. We have a basic installation guide you can read. Works and warnings Check whether there are any known works or warnings that might be causing the problem. Transmitter faults By using our Transmitter Checker , you can check what MW/LW radio services are available at your location. It will also show you any transmitter faults. Weather AM reception can vary a great deal from day to night because of differences in the atmosphere. You may get good, clear reception during the day, but after sunset the signal may fade or become distorted. This is why you can often hear radio stations from outside the UK at night. Our information on how clear skies and fine weather can affect your radio reception may be useful, please see our Weather Guide. Buzzing, clicking and pops This may mean an electrical item in your home, or nearby, is interfering with your MW/LW radio. This is causing the buzzing, clicking or pops sounds you can hear. See our guide on Buzzing and Clicking. If you are still having problems see our sister site RTIS for further information.

Radio reception problems due to high pressure

Effect of Weather on Reception. Weather-related problems tend to happen mainly in the summer, when high pressure can cause a radio signal to travel further than it would normally. This is known as tropospheric ducting. For more information see our guide on tropospheric ducting . If this distant radio signal is on the same frequency as the one you are listening to it can cause a reception problem. This is because your radio will struggle decoding two radio stations on the same frequency. This is known as co-channel interference The effect can last from a few hours to a few days and can cause intermittent effects on the service during that time. What to do: There is nothing that can be done but to wait until the weather changes. We have no control over it. If your problem is due to the weather, it should go away once the weather changes. Works and warnings Check our works and warning page to see if there any current weather problems.

What type of radio aerial do I need?

FM Radio The most common FM radio aerial on a portable radio is a telescopic one. To get the best reception extend the aerial fully and move the aerial and radio around until you get the best reception. If using a hi-fi with a wire aerial, again extend as much as possible to get the best signal. External aerials are also available for FM radio and will significantly improve reception. The aerial and cables need to be well maintained and you will need a radio that has an option to connect an external aerial.

AM Radio A radio which can tune to medium and long wave services usually has an aerial built in, which you cannot see. As the aerial is directional, by simply turning the radio you will be able to get the best reception. AM does not use the telescopic aerial.

Some hi-fi’s have external AM aerials that tend to look like many wires wound around a plastic loop. This needs to be rotated to find the best signal.

DAB radio You need to have a suitable DAB aerial to receive DAB services. Portable DAB radios will usually have a telescopic one, but if you are retro-fitting a DAB radio into a car, you may need to add a DAB aerial. External aerials are also available for DAB and will significantly improve reception. The aerial and cables need to be well maintained and you need a radio with the option to connect an external aerial. Unlike the other services, all the predictions of DAB coverage are for indoor coverage.

FM Radio in the car

Fading and Hissing If you normally can receive a service, but you are now finding it is fading in and out, or you can hear hissing, this could be down to one of three things. The first is a fault with the local FM transmitter. Secondly, if you know your location, you can use our  transmitter checker  to see whether there is a problem. Thirdly, if not, then you will need to check the radio and aerial to confirm they are both working properly. Interference Poor FM reception can also be caused by equipment used in the vehicle. For example, phone chargers or dash cams sometimes cause interference and affect your radio signal. Try unplugging the items to see if one of them is causing any interference. Reception in Tunnels Depending on the specific tunnel and station, Radio reception can cut out or be lost when driving through tunnels. If the tunnel is deep, the radio waves will not reach into the centre, so your radio cuts out. Some tunnels are fitted with signal distribution systems both for FM and DAB so the signal will not be lost while in the tunnel. Or it could be “To help maintain the radio signals within the tunnel” Tuning Most FM car radios have a Radio Data System (RDS) built in. We use the RDS to ‘tell’ your radio if there is a better or stronger frequency for the radio service you are listening to, as you travel around. However, if you are using a frequency, you have preset and there is no radio service on that frequency in your location, then the RDS may not work. At that point you will need to tune your radio until you find a signal. Aerials If you are having continuous reception problems, check your car aerial for damage. If you have an extendable aerial, make sure it is fully extended to give the best possible reception. Local Radio Travel News The RDS system is set up to detect local radio travel news. The way to turn traffic announcements on and off on varies between radios. Check your car manual for yours.

AM radio in the car

Interference from car electrical systems

Interference to MW or LW reception in a car can be caused by many electrical systems within your car. From the ignition system to windscreen wipers or indicators. It usually sounds like whining or crackling sound, depending on the cause. Turning each element on and off to see if it goes away is one method to determine the cause but you may need to speak to an auto specialist

Interference from other electrical equipment

Other causes of interference to MW or LW radio in the car can include mobile phone chargers and dashcams. Check that connections are secure and cables are not damaged and see if the interference goes away of you move the equipment to other areas in the car.

On the move

MW/LW radio can also be affected by structures such as bridges and tunnels.

In simplistic terms, the size of the MW/LW wavelength is bigger than the radius of the entrance and struggles to reach into the tunnel or under the bridge. FM wavelengths are smaller so can usually reach in further by bouncing along the tunnel walls before they lose too much power

There’s nothing that can be done to improve this until you drive out from the tunnel or away from the bridge.

Radio Reception Help Guides

Buzzing and clicking on your radio.

The buzzing and clicking lasts from a few seconds to a minute at a time. Switch off heating systems and see whether the problem goes away. If the problem persists when you turn the heating system back on, the problem could be with the thermostat, which may need to be repaired or replaced.

Light switches

To find out if a particular switch is causing the problem, try turning the lights off one at a time.

Many people are now using low power LED lights instead of the more traditional varieties. However, if the original light used a transformer rather than directly running off the mains, it is possible the transformer is causing the interference. This is because the transformer would have been designed to operate at the higher power and not the lower power the LED lights use. This has the potential to cause electrical interference.

Street lamps

Street lamps can sometimes cause buzzing and crackling sounds on your FM radio. Keeping a note of when each lamp comes on and goes off will help to identify whether this is the cause of your interference. If it is, contact your local council.

Passing traffic

A faulty or uncompressed engine can cause a distinct buzzing 'whine' which varies with engine speed - motorcycles tend to be the worst. Try to move your radio away from the street or use an external aerial.

Electric motor

An electric motor is used in many appliances such as electric lawnmowers, washing machines, drills and hairdryers etc. A faulty motor can cause electrical interference. Check any appliance with an electric motor by moving your radio away from it to see whether the sound improves. If you have several appliances with electric motors you may need to turn them all off and try the above one at a time.

With all of these potential causes, it is worth keeping a log for at least two weeks to determine whether there are any patterns or trends to the interference.

Hissing and Fading on your FM radio

This can be due to: Reduced transmitter power Use our Transmitter Tool to see whether your local transmitter is currently affected by maintenance work. Stereo Signal Try moving the radio to another position, such as near a window, higher up, or another room. If you get hiss when listening to a stereo signal try switching to mono. Stereo reception needs a stronger signal than mono. Aerial If you have a portable radio you will be able to pick up more of the receivable signal if your telescopic aerial is fully extended. For hi-fi systems check your aerial isn’t broken or become loose. If you have an external or loft aerial check they are functioning correctly. Tuning to the wrong transmitter Use our Transmitter Tool to check you are tuned to the best frequency for your area, as you can often pick up more than one signal. Weather Very occasionally, the weather, usually high pressure, can result in a weakened signal. There is nothing anyone can do about this and the only answer is to wait for the weather to change. For more information see our guide on how weather can affect radio reception .

Radio Waves

WHAT ARE RADIO WAVES?

An old photograph of Karl Jansky standing in front of his radio telescope.

Radio waves have the longest wavelengths in the electromagnetic spectrum. They range from the length of a football to larger than our planet. Heinrich Hertz proved the existence of radio waves in the late 1880s. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of the coil transmitter were picked up by the receiving antenna, sparks would jump its gap as well. Hertz showed in his experiments that these signals possessed all the properties of electromagnetic waves.

You can tune a radio to a specific wavelength—or frequency—and listen to your favorite music. The radio "receives" these electromagnetic radio waves and converts them to mechanical vibrations in the speaker to create the sound waves you can hear.

RADIO EMISSIONS IN THE SOLAR SYSTEM

Astronomical objects that have a changing magnetic field can produce radio waves. The radio astronomy instrument called WAVES on the WIND spacecraft recorded a day of bursts of radio waves from the Sun's corona and planets in our solar system.

Data pictured below show emissions from a variety of sources including radio bursts from the Sun, the Earth, and even from Jupiter's ionosphere whose wavelengths measure about fifteen meters in length. The far right of this graph shows radio bursts from the Sun caused by electrons that have been ejected into space during solar flares moving at 20% of the speed of light.

A graph showing the frequency of radio emissions over a 24 hour period. The frequencies over 1000 kHz are those originating from the Sun. Frequency emissions between 600 and 1000 kHz are from Jupiter while the Earth produces frequencies between 200 and 400.

RADIO TELESCOPES

Radio telescopes look toward the heavens to view planets, comets, giant clouds of gas and dust, stars, and galaxies. By studying the radio waves originating from these sources, astronomers can learn about their composition, structure, and motion. Radio astronomy has the advantage that sunlight, clouds, and rain do not affect observations.

Since radio waves are longer than optical waves, radio telescopes are made differently than the telescopes used for visible light. Radio telescopes must be physically larger than an optical telescopes in order to make images of comparable resolution. But they can be made lighter with millions of small holes cut through the dish since the long radio waves are too big to "see" them. The Parkes radio telescope, which has a dish 64 meters wide, cannot yield an image any clearer than a small backyard optical telescope!

A VERY LARGE TELESCOPE

In order to make a clearer, or higher resolution, radio image, radio astronomers often combine several smaller telescopes, or receiving dishes, into an array. Together, these dishes can act as one large telescope whose resolution is set by the maximum size of the area. The National Radio Astronomy Observatory's Very Large Array (VLA) radio telescope in New Mexico is one of the world's premier astronomical radio observatories. The VLA consists of 27 antennas arranged in a huge "Y" pattern up to 36 km across (roughly one-and-one-half times the size of Washington, DC).

The techniques used in radio astronomy at long wavelengths can sometimes be applied at the shorter end of the radio spectrum—the microwave portion. The VLA image below captured 21-centimeter energy emissions around a black hole in the lower right and magnetic field lines pulling gas around in the upper left.

An image showing a ball of bright white and red in the lower right with strands in red arching across the top and left indicating magnetic field lines.

THE RADIO SKY

If we were to look at the sky with a radio telescope tuned to 408 MHz, the sky would appear radically different from what we see in visible light. Instead of seeing point-like stars, we would see distant pulsars, star-forming regions, and supernova remnants would dominate the night sky.

Radio telescopes can also detect quasars. The term quasar is short for quasi-stellar radio source. The name comes from the fact that the first quasars identified emit mostly radio energy and look much like stars. Quasars are very energetic, with some emitting 1,000 times as much energy as the entire Milky Way. However, most quasars are blocked from view in visible light by dust in their surrounding galaxies.

A dark image with defined spots of blue in lower left, and green in upper right, with a spot of yellow in the center.

Astronomers identified the quasars with the help of radio data from the VLA radio telescope because many galaxies with quasars appear bright when viewed with radio telescopes. In the false-color image below, infrared data from the Spitzer space telescope is colored both blue and green, and radio data from the VLA telescope is shown in red. The quasar-bearing galaxy stands out in yellow because it emits both infrared and radio light.

Next: Microwaves

National Aeronautics and Space Administration, Science Mission Directorate. (2010). Radio Waves. Retrieved [insert date - e.g. August 10, 2016] , from NASA Science website: http://science.nasa.gov/ems/05_radiowaves

Science Mission Directorate. "Radio Waves" NASA Science . 2010. National Aeronautics and Space Administration. [insert date - e.g. 10 Aug. 2016] http://science.nasa.gov/ems/05_radiowaves

Discover More Topics From NASA

James Webb Space Telescope

$The image is divided horizontally by an undulating line between a cloudscape forming a nebula along the bottom portion and a comparatively clear upper portion. Speckled across both portions is a starfield, showing innumerable stars of many sizes. The smallest of these are small, distant, and faint points of light. The largest of these appear larger, closer, brighter, and more fully resolved with 8-point diffraction spikes. The upper portion of the image is blueish, and has wispy translucent cloud-like streaks rising from the nebula below. The orangish cloudy formation in the bottom half varies in density and ranges from translucent to opaque. The stars vary in color, the majority of which have a blue or orange hue. The cloud-like structure of the nebula contains ridges, peaks, and valleys – an appearance very similar to a mountain range. Three long diffraction spikes from the top right edge of the image suggest the presence of a large star just out of view.$

Perseverance Rover

Parker Solar Probe

Are Radio Waves Light Waves? Everything You Need to Know!

Last Updated on Mar 12 2024

Radio waves are light waves because they’re made up of photons, little particles of energy that vibrate along the electric and magnetic fields. If our eyes could perceive radio waves, looking up at the night sky would reveal a world of colors that are otherwise invisible to us, and communications towers would emit rainbow-colored waves into the atmosphere.

That said, when people say, “light waves,” they might be referring to visible light , the only part of the electromagnetic spectrum that is visible to the naked eye. Sometimes, infrared and ultraviolet, which are not visible to us, are included. Along with Infrared, visible light, ultraviolet, x-rays, gamma rays, and microwaves, radio waves are better referred to as electromagnetic radiation.

Do Radio Waves Travel at the Speed of Light?

It’s easy to think that radio waves travel at the speed of sound. After all, most of us immediately associate the word, radio, with listening to music or the news. But radio waves are light waves , and therefore, they travel at lightspeed. In the vacuum of space, light travels at approximately 186,282 miles per second. That’s almost the distance that a modern vehicle covers over its entire lifetime!

Do Radio Waves Travel Forever in Space?

In space, radio waves will keep traveling infinitely. In fact, early radio signals from Earth have already traveled 303 trillion kilometers through space, way past our nearest neighboring star. On Earth, scientists use giant radio telescopes to listen for signals from distant galaxies. But the further radio (or any other light) travels, the more it will dissipate and become weaker.

Radio Astronomy and the Wow! Signal

Using radio telescopes, radio astronomers learn more about our universe by looking for radio signals from gas blasts in deep space, the ticking signals of pulsars, and emissions from gas giants.

One of the most extraordinary radio signals to have ever been recorded is the Wow! signal . The mysterious signal detected in 1977 appeared to have come from Sagittarius. Some people believe the Wow! signal may have come from an extra-terrestrial intelligent civilization, while others believe it had a more natural source—astronomers are still undecided!

On Earth, radio waves will travel for a long distance before they dissipate and become weaker. In long-distance communication, High Frequency (HF, or skywave) signals can be directed towards the ionosphere, where the radio waves will bounce back down towards their intended destinations.

Does Wi-Fi Use Radio Waves?

WiFi uses high-energy radio waves to transmit data—which, on the electromagnetic spectrum, are referred to as microwaves. Bluetooth devices also transmit data along the same low-power microwave range.

In fact, radio and microwaves are used by humans extensively throughout our lives. We use radio or microwave for watching television, connecting to the internet, making telephone calls, sending text messages, radio astronomy, and navigation. Meanwhile, we also use microwaves in medical settings for cancer treatment, and at home for cooking and preparing meals.

Final Thoughts

Radio waves are a type of electromagnetic radiation. They have the longest wavelengths, the lowest energy, and the lowest frequency on the electromagnetic spectrum. Radio waves are light, but they are not visible to human eyes. On Earth, we are surrounded by radio waves. While some are naturally occurring, others are man-made.

https://hubblesite.org/contents/articles/the-electromagnetic-spectrum
https://www.icrar.org/gleam/
https://science.nasa.gov/ems/05_radiowaves
https://www.space.com/15830-light-speed.html
https://www.consumerreports.org/car-repair-maintenance/make-your-car-last-200-000-miles-a8010293375/
https://serc.carleton.edu/quantskills/activities/botec_radio.html
https://public.nrao.edu/radio-astronomy/the-science-of-radio-astronomy/
https://astronomy.com/news/2020/09/the-wow-signal-an-alien-missed-connection

Featured Image Credit: Pilotsevas, Shutterstock

Table of Contents

About the Author Cheryl Regan

Cheryl is a freelance content and copywriter from the United Kingdom. Her interests include hiking and amateur astronomy but focuses her writing on gardening and photography. If she isn't writing she can be found curled up with a coffee and her pet cat.

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What Is a Monocular Used For? 8 Common Functions

How to Clean a Telescope Mirror: 8 Expert Tips

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IMAGES

Do Radio Waves Travel at the Speed of Light? We Reveal All
Do Radio Waves Travel at the Speed of Light? Exploring the Physics
Radio waves from famous FRB surprisingly long and late
Understanding The Physics Behind How Fast Radio Waves Travel
How Radio Waves Work?
How far have Radio Waves traveled?

VIDEO

Shortwave tips Bandwidths Frequencies Day and night propagation
How Data Travels in air (RADIO WAVES)
Electromagnetic wave
Understanding "Radio Wave": A Dive into Invisible Signals
Engineering Across The Cosmos (SFM)
Seeing the Invisible: Astronomical Radio Waves

COMMENTS

Why Do Radio Signals Travel Farther at Night Than in the Day?
Not all radio waves travel farther at night than during the day, but some, short and medium wave, which AM radio signals fall under, definitely can given the right conditions. The main reason this ...
Why do you hear some radio stations better at night?
As it turns out, the ionosphere reflects certain frequencies of radio waves. So the waves bounce between the ground and the ionosphere and make their way around the planet. The composition of the ionosphere at night is different than during the day because of the presence or absence of the sun. You can pick up some radio stations better at ...
Why Do Radio Signals Travel Farther at Night than in the Day?
Not all radio waves travel farther at night than during the day, but some, short and medium wave, which AM radio signals fall under, definitely can given the right conditions. The main reason this is the case has to do with the signal interacting with a particular layer of the atmosphere known as the ionosphere, and how this interaction changes ...
Radio 101: Why AM stations reduce power at night
Basically, because of the way radio waves travel at night, many Relevant Radio AM stations are require to reduce power when the sun sets in order to avoid massive interference with other stations. The good news is that Daylight Savings Time is on the horizon—March 8 this year—meaning we'll be gaining an extra hour of daylight. As summer ...
Why Do AM Signals Travel Farther?
AM signals can travel farther than FM signals due to the size of the wavelength. The wavelengths are larger and thus have no issue passing through obstacles such as trees, buildings, and hills. The traveling distance of AM signals amplifies even more at night. Whereas the radio signal only travels about 100 miles during the day (which is still ...
Is AM Radio Better at Night?
AM radio is better at night due to the landscape of the ionosphere, which changes after sunset. The signals can travel much further due to what's known as sky-wave propagation. Additionally, some AM stations must stop operating after dark to reduce interference, which also helps some stations come through more clearly.
Why AM Listening is Better at Night
Shop ccrane.com. July 23, 2018. Why AM Listening is Better at Night. If you listen to AM radio stations at night that are just impossible to pick up during the day, chances are you're benefiting from sky-wave propagation. Propagation is just the technical word for how radio signals travel through the air. Sky-wave propagation is the specific ...
Radio propagation
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1] : 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and ...
Catch a Wave: Radio Waves and How They Work
Perhaps you have noticed that AM radio tends to sound better at night than during the day. The reason for this is that the sun is a big source of natural AM radio waves. ... FM radio waves on the other hand do not travel well through solid objects. This is the reason FM stations sometimes fade in and out when driving in mountainous areas ...
Why AM Stations Must Reduce Power, Change Operations, or Cease
Most AM radio stations are required by the FCC's rules to reduce their power or cease operating at night in order to avoid interference to other AM stations. FCC rules governing the daytime and nighttime operation of AM radio stations are a consequence of the laws of physics. Because of the way in which the relatively long wavelengths (see Footnote 1) of AM radio signals interact with the ...
Tuning Into the Atmosphere: How Humidity Influences AM Radio Signal
The Journey of AM Radio Waves. AM radio signals operate in the Medium Frequency (MF) band of the electromagnetic spectrum, usually from 535 kHz to 1605 kHz. ... can sometimes allow AM radio signals to travel thousands of kilometers. Humidity and AM Radio Signals. Humidity, defined as the amount of water vapor in the air, influences AM radio ...
waves
The signal is sent to the brain where it is interpreted. As the sound wave progresses through the air, its energy slowly dissipates. This is why sound is louder closer to the source and quieter further from the source. Wave interference occurs when two or more waves disturb the same air molecules.
Learning Lesson: AM in the PM
Demonstrate that AM radio signals can travel many 100s of miles at night. The student will listen to as many radio stations as possible, obtaining the call signs and places of origin during the evening (after sunset) hours. TOTAL TIME. 30 minutes to two hours during the evening (or early in the morning before sunrise). SUPPLIES.
How do AM radio signals change with time of day?
At night, due to the absence of ionizing sunlight, the ions recombine and this charge is drained due to absence of a source of ionizing radiation. A small part, however, remains due to cosmic rays. A consequence of all this is that during the day, AM radio signals can't really travel by skywave, and so travel by groundwave, diffracting around ...
Why Do Radio Signals Travel Farther At Night Than In The Day?
January 28, 2015 at 4:15 pm. Not all radio waves travel farther at night than during the day, but some, short and medium wave, which AM radio signals fall under, definitely can given the right ...
Understanding Radio Waves: Nature and Properties
Understanding Radio Waves: Nature and Properties. Radio waves, the unsung heroes of the electromagnetic spectrum, serve as the cornerstone of amateur radio, enabling enthusiasts to experiment, communicate, and explore a world invisible to the naked eye. These waves, oscillating electric and magnetic fields that travel through space at the speed ...
Radio Waves
Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than visible light. Humans use radio waves extensively for communications. This radio tower has both rectangular and circular antennas to transmit and receive radio frequency energy. The wavelengths of radio waves range from a few millimeters (tenths ...
radio communications
The night effect is actually a mirage. Listening to radio communications originating from below the radio horizon is like looking at a looming: Looming optical illusion, source: SKYbrary. Both are strange things, unless we force ourselves to take into account electromagnetic waves (including light) don't travel in straight line but are subject ...
Why AM Listening is Better at Night
Listening to AM, and scanning the AM dial between sunrise and sunset is a fun way to discover how far a sky-wave signal can travel to reach you. During the baseball season, you can use the sky-wave to tune in some night games played in different parts of the country. In Northern California (where C. Crane is based), as in other places around ...
Why is medium wave reception worse at night?
At night medium wave radio signals can travel much further than during the day. This means your radio is able to receive more radio channels either using the same frequency as the service you are ...
Radio Waves
Radio waves have the longest wavelengths in the electromagnetic spectrum. They range from the length of a football to larger than our planet. Heinrich Hertz proved the existence of radio waves in the late 1880s. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of ...
Are Radio Waves Light Waves? Everything You Need to Know!
Radio waves are a type of electromagnetic radiation. They have the longest wavelengths, the lowest energy, and the lowest frequency on the electromagnetic spectrum. Radio waves are light, but they are not visible to human eyes. On Earth, we are surrounded by radio waves. While some are naturally occurring, others are man-made.
Radio Waves
Frequency modulation allows FM waves to encode more information than does amplitude modulation, so FM broadcasts usually produce clearer sounds than AM broadcasts. However, the relatively short wavelengths of FM waves means that they don't reflect off the ionosphere as AM waves do. Instead, FM waves pass through the ionosphere and out into space.

Why do you hear some radio stations better at night than in the day?

Frequently Answered Questions

Why Do Radio Signals Travel Farther at Night than in the Day?

Bringing Christ to the world through the media

Radio 101: Why AM stations reduce power at night

Is AM Radio Better at Night?

Why Is AM Radio Stronger at Night?

The FCC’s Involvement with Stronger AM Radio Signals at Night

How Much Further Can AM Radio Signals Reach at Night?

The Role of Sunspots in Improving AM Radio by Night

Why Is My AM Radio Signal Still Fuzzy at Night?

Interference

Antenna Positioning

Reduced Power

Wrapping Up

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