AM and FM radio are significant influences on the people of the United States. They broadcast news and entertainment that get us through the workday and help us enjoy the big game on the weekends. In emergencies, we may depend on them for critical information about personal safety.
What is the difference between AM and FM Radio Signal?
The difference between AM and FM radio signal is Amplitude and frequency. AM radio varies the amplitude or strength of the carrier wave to encode information, while FM radio changes the frequency of the carrier wave. This results in FM generally having a clearer sound quality than AM, making it more suitable for music, while AM’s longer wavelength allows it to travel greater distances and through obstacles, making it ideal for talk radio and news.
Here is the list of other major differences between AM Radio Signal and FM Radio Signal.
| Parameter | AM Radio Signals | FM Radio Signals |
|---|---|---|
| Modulation Type | Amplitude Modulation | Frequency Modulation |
| Frequency Range | Typically 530 – 1700 kHz | Typically 88 – 108 MHz |
| Sound Quality | Generally lower | Superior with less static |
| Interference | More susceptible to interference | Less susceptible to interference |
| Range | Longer range at night | More consistent range |
| Bandwidth | Narrower (about 10 kHz) | Wider (about 200 kHz) |
| Application | Mostly for talk radio, news | Music, talk shows, news |
| Multiplexing | Not common | Stereo broadcasting possible |
| Susceptibility to Noise | High (static) | Low (clearer sound) |
| Cost | Generally cheaper transmitters | More expensive transmitters |
AM and FM radio are an excellent tool for advertising and sending important messages to a broad audience. Read on to learn the difference between AM and FM.
Learn About Pros of AM Signals and Pros of FM Signals | Cons of AM and Cons of FM.
Modulation is What Makes Radio Work
Amplitude Modulation and Frequency Modulation are what make us able to decode what a radio signal is sending out. Think of your standard radio wave. It has the same modulation sent from the receiver. When it comes to our radios, it must change to make itself fit whatever way the listener is using. Waves are constant, but the way they are decoded is going to change.
Both types of modulation require a carrier wave to make them work. What makes the difference between AM and FM is how this carrier wave is modulated and interpreted by our listening device. AM decodes the amplitude of the wave while FM uses the frequency. While each has its advantages, there are also disadvantages to each.
The Pros and Cons of AM and FM Radio
Something that people always want to know is which one of the signals is better. That’s something that doesn’t have a straightforward answer as each has advantages that could be useful depending on the situation. People use the radio for many different things. For instance, you could use an old AM radio to listen to the local high school football game.
The Pros of AM Radio are:
- Easy to find a signal – AM will have an easy signal to find with some simple electronic equipment. You’ve seen it times before in movies from the rock revolution, where kids make their own radios to listen to the music that their parents don’t like. This works because the wave is so easy to ‘catch’ and decode.
- Lots more coverage – AM has a more narrow bandwidth, which makes it able to cover more area but with less sound quality. AM works best as a talk-radio format to deliver news updates or weather changes to a much larger audience than you can get with FM.
- Propagation – One of the cool things about how AM works is that the wave can move about more easily at night. It can be bounced off almost anything and send your station’s waves way out into the area and possibly the cosmos. The AM waves that don’t bounce off anything travel into open space.
- No fluttering – You see it all the time in the mountains or the city. FM waves can be deflected and miss the radio entirely. This causes a fluttering that can affect music and how it sounds. This isn’t a problem with AM, which is mainly for talk radio and news stations that don’t have a pronounced flutter.
The cons of AM Radio are:
- Static – The biggest drawback of AM radio is that it is very susceptible to interference. This interference takes the form of static for the listener. It can be caused by large electric fluctuations and lightning storms. Also, there can be a bleed-over from other stations. This ruins broadcasts and could spoil much-needed information.
- Reception issues with some receivers – The radio towers that put out the AM signal run at 15kHz. This high level of reception means that some receivers are going to be unable to decode the signal. The radio receivers we use only get to about 5kHz, which leaves a lot of signal still to be decoded.
FM radio is the kind that people today are more comfortable with. It is home to some of the most notable radio and news stations around the country. Talk radio and oldies, dominate AM radio. While FM caters to listeners who want to hear the latest music hits. Today’s youth grew up with FM and it’s much more prevalent than the older AM.
The pros of FM radio are:
- Less noise – The most noticeable pro of using FM radio is how good the media sounds. The music and broadcasts that come from FM are less susceptible to interference and static. It makes for more enjoyable listening and keeps the user jumping around to different stations for a stronger signal.
- Set service locations – The way larger FM stations are set up gives them authority over a specific place. Their listening area gives them an explicit area to conduct their shows and advertisements. That’s why certain parts of the country have the same dial number station with different programming.
- Less radiation – AM stations pump out tons of power into the air. That makes the waves stronger and sends a dangerous amount of electromagnetic waves. These waves can potentially cause the body to experience headaches or a host of other medical problems that come from overexposure.
FM isn’t perfect, either. It’s a complicated wave to decode while taking some technological equipment to listen to it. FM stations are at a much higher frequency, and it takes more than just one decoder to make the thing work. They also lack the power to push a big signal like an AM station.
Also, read How do Ham Radios Work? and CB vs Ham Radio
The cons of FM radio are:
- Local stations – The power governed to smaller stations usually only have a large enough area to cover their location and few other towns. This means that you are plugged into the local heartbeat when you are listening to an FM station. This is a disadvantage because if you drive a long way, you will have to find new radio stations.
- The signal can be blocked – While the FM signal is clear, it can be blocked from transmission by buildings or mountains. If you drive through a mountain pass, you may notice that the signal will die. The same goes for driving through a large city. Skyscrapers will block an FM signal just like a mountain.
- More decoding stages – While an AM receiver can be made from some simple electronic equipment, FM needs two decoding stages to function. Interior pieces called the limiter and discriminator remove any imperfections in the wave before sending it out to the radio speakers.
Conclusion
The difference between AM and FM is static. FM radio was designed to remove the static from transmissions and create a clear sound. That sound brought out the best parts of the music. AM is very powerful and can conduct a signal over a much broader area but doesn’t compete with sound quality in music or tone in news broadcasts.
FM and AM created a generation of kids who danced to the tunes spewing forth as if they heard the music live and in person.
Today, AM serves as a way for local news stations and municipalities to deliver messages in a state of emergencies such as an earthquake or tornado. It also tends to cater to an older demographic. FM, although available in an emergency, targets a more general audience.
Resources:
- Difference b/w AM and FM Radio Signal
- The Disadvantages of FM radio
- Advantages of FM radio
- What’s the difference between FM and AM Signal
