AM and FM Radio As Fast As Possible
Techquickie
·Techquickie
·2016-05-06
·
1,155 words · ~5 min read
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Maybe it's just because I'm old, but even though Spotify, podcasts, and other
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forms of audio streaming seem to rule the day, there's just something
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comforting about the simplicity of turning a knob on the radio and
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listening to what's happening on the airwaves. Even in the digital age, radio
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has maintained a fair amount of popularity since the first public
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broadcasts in the early 20th century.
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But since radio has been around since
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long before we had things like digital decoders that turn electrical impulses
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into music, how the heck do simple cheap
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radios know how to convert an electromagnetic radio signal into a I
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don't know, let's say a basketball game or a weather report or a you know Justin
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Bieber's greatest who put that crap in my script. Anyway, AM radio broadcasts
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showed up before FM. So, we'll start with those. An AM station will broadcast
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a signal at a constant frequency, but
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will add the soundwave representing the actual audio to that base signal. It's
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also called a carrier wave, resulting in the height or amplitude of the wave
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changing accordingly. This is where the term AM comes from, as it stands for
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amplitude modulation. You can get your radio to play back this signal as actual
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music or dialogue by tuning it to
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whatever frequency the station that you're looking for broadcasts at. This
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makes your antenna resonate at the frequency and ignore everything else in
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the air. So, very simple radio tuners are actually little more than coils of
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wire. How many turns of the wire will determine what frequency you're picking
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up. Cool, right? The antenna actually creates an electrical current that
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corresponds to the radio signal. This current is sent to other parts of your
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radio that filter out the irrelevant parts of the signal and send it to your
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speakers or your headphones as changes in voltage which drive those speakers
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and produce sound. It's actually pretty remarkable that this is all done without
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any digital decoding by something like a a CPU. It's a completely analog process
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that made it possible for news, music, and entertainment to stream into homes
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decades before the internet or even TV.
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FM broadcasting works somewhat similarly, though with FM, it's the
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frequency of the signal that gets changed, hence the F in FM. FM radios
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have a special transformer inside them that basically sits idle as long as
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exactly whatever frequency you're tuned to hits your antenna. But once it
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detects a small change in that frequency, it outputs a voltage that
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makes your speakers emit a certain sound. So let's say you're tuned to 99.5
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FM on your dial. Since FM works by using
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very small changes in frequency to carry a signal, you are actually tuned to
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signals just above and below 99.5 MHz,
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which makes that transformer send the voltage to your speakers. Now, although
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this process makes FM more complicated to engineer than AM, you often get a
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much clearer, higher quality signal. FM
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is less susceptible to interference as well because interference often
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manifests as amplitude spikes. An AM
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radio would see these spikes as actual
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sound to produce and it would end up coming out of your speakers while FM
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cares about variations in frequency rather than amplitude. So an FM radio
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can just ignore that type of interference and the death metal you're
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listening to will come out sounding just as clear and angry as ever. FM also has
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the advantage of having much higher bandwidth than AM due to the
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mathematical properties of frequency modulation. This allows for lots of
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wiggle room in the signal to create more sounds more accurately, making FM the
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clear choice for music, while AM is often just fine for stuff where
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highfidelity isn't a big deal, such as talk radio. But if FM is so superior,
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then why do AM stations seem to have so
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much better range? Well, it's because AM
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wavelengths are much longer, meaning that they can move more effectively
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following even the curvature of the Earth and deal with obstacles like
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buildings, whereas you can quickly lose highfrequency FM signals if you start
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putting stuff in the way. AM frequencies also allow signals to cause free
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electrons in the ionosphere to oscillate at the same frequency as the radio wave
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that hits them. Meaning that AM signals can actually reflect off the upper
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atmosphere. At night, there are more free electrons hanging out in the sky,
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which is why you can sometimes hear AM stations from hundreds of miles away
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after the sun goes down, as opposed to FM, which tends to go right through the
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atmosphere. Of course, this may not seem impressive when the internet allows you
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to listen to highquality digital broadcasts from the other side of the
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world, no problem. But good old analog radio still has the distinct advantage
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of only requiring a $10 receiver with no
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subscription fees and very high ease of use, especially for people who might not
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be terribly tech-savvy. And of course, your radio will keep working even if
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your finicky internet connection goes out. Sometimes simpler is indeed better.
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days by going to freshbooks.com/tequicky which is linked in the video description
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and entering techquicki in the how did you hear about us section. So thanks for
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watching guys. If you like the video like it. If you disliked it, dislike it. If you want to check out our other
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channels, boom, we got a link right there. If you want to leave a comment with suggestions for future fastest
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possibles, you can do that below. And as always, don't forget to subscribe and follow and all that good stuff. See you
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next time.