We (Jordan and Eduardo) wanted to conduct research on the fundamentals of how radios work, their relation to the electromagnetic spectrum, and what makes them output the beautiful music we hear.

We looked through a variety of websites and fact-checked the information with our parents to confirm our research that we have shared in our presentation

What is The Electromagnetic Spectrum?

The electromagnetic spectrum or EMS is the spectrum which contains waves of different frequencies and wavelengths. This spectrum consists of 7 wave categories. Some of these waves are very relevant to our day-to-day lives.

The spectrum starts at radio waves, which have a relatively low frequency but a very long wavelength and are used for radio communication. Gamma rays, at the end of the spectrum, have very high frequency and very short wavelengths, as small as picometres (1 pm = 10^-12 or  1 trillionth of a metre)! In the middle is the visible light part of the spectrum, which is the range of waves that allows us to see everything around us!

 

Signals

Carrier Wave/Signal

 

A carrier wave is a high frequency wave (typically sinusoidal) that helps convey a message wave to a radio receiver to output audio after the demodulation has been done. Carrier waves help cause less interference and make the message travel further. Carrier waves are removed after demodulation.

Carrier waves are periodic, fixed frequency sinusoidal waves. Both the transmitter and the receiver need to be able to generate these waves so that modulation and demodulation can be performed.

Message Wave/Signal

The message wave is what you want to transmit to the receiver. It gets modulated onto the carrier wave. These waves are typically at a lower frequency than the carrier waves that they have been modulated onto. The image below shows an example of a lower frequency signal wave.

Do keep in mind that message waves are not constant like the image above; they have many changes in frequency and amplitude, since waves from music always have ups and downs in pitch and volume. Being low frequency waves, they do not have enough energy to be transmitted in long distances, thus the need for high frequency / high energy waves to “carry” them.

Radio Components

Radio Transmitter

A radio transmitter is a device that sends out modulated electromagnetic waves for a radio receiver to capture. Every radio station has a transmitter to broadcast their content. 

 

 

 

Radio Receiver

A radio receiver is an electronic device that receives modulated signals from transmitters and demodulates the signal by filtering out the carrier wave so that it can play the original content (the message wave).

 

 

Modulation

What is modulation?

Modulation is the process of modifying a carrier wave’s properties (frequency, amplitude, or phase) with the properties of the message or signal wave so it can be embedded onto the carrier wave. Remember that the message has a much lower frequency than the carrier wave, so it cannot travel far. The energy of the carrier wave is what makes it possible for the message to be transmitted over long distances.

Another important aspect of the FM radio frequencies is that their associated wavelengths are in the range of 2 to 4 metres, which makes the FM antennas that are just a few centimetres long appropriate for capturing these modified carrier waves. 

 

As seen in the image to the right, there are various modulation techniques beyond those commonly used in continuous-wave modulation.

 

Types of modulation: Image comparison

On the right, the image shows a comparison between 2 of the types of continuous-wave modulation: amplitude and frequency modulation. There is also the carrier and message wave.

Ignoring the carrier wave, you can see how AM and FM are related to the message wave. 

The AM wave adjusts its amplitude according to the message wave, while the FM wave adjusts the same way, but in frequency.

Phase modulation is not in the image for the sake of simplicity, but if it was here, the PM wave would show changes along the x-axis.

Concepts, Conclusion and Review

The concepts we have studied are:

• The electromagnetic spectrum (EMS)
• Modulation
• How transmitters can transmit radio waves to radio receivers
• How we can listen to FM radio with a receiver
• Carrier and Message waves

 

The research that we worked on concluded that radio waves are a part of the Electromagnetic Spectrum (EMS). We also discussed that radio transmitters use a carrier signal that is modified with a message signal, so that radio receivers can take the wave through an antenna, demodulate the carrier wave, extract the message wave, and play it through a speaker. We studied the two most used types of continuous-wave modulation, AM and FM, and we finally learned what radios do, answering how they work!

 

 

Equation

 

𝝺  = Wavelength                 𝝺 = c ÷ f

c = Speed of Light            --------------

f =Frequency                      f = c × 𝝺

 

Images

 

Electromagnetic Spectrum

 

Carrier Wave

Message Wave

Types of Modulation: What is Modulation

 

Concepts, Conclusion and Review

The concepts we have studied are:

• The electromagnetic spectrum (EMS)
• Modulation
• How transmitters can transmit radio waves to radio receivers
• How we can listen to FM radio with a receiver
• Carrier and Message waves

 

The research that we worked on concluded that radio waves are a part of the Electromagnetic Spectrum (EMS). We also discussed that radio transmitters use a carrier signal that is modified with a message signal, so that radio receivers can take the wave through an antenna, demodulate the carrier wave, extract the message wave, and play it through a speaker. We studied the two most used types of continuous-wave modulation, AM and FM, and we finally learned what radios do, answering how they work!

Image Citations

 

Radio Emoji - https://iconduck.com/emojis/130607/radio

Red Question Mark Emoji - Unfindable.

Message and Carrier* Wave/Signal Picture(s) - https://www.shutterstock.com/image-vector/wavy-waving-lines-curve-curvy-sinuous-2131572741

Electromagnetic Spectrum(EMS) Picture - https://link.springer.com/chapter/10.1007/978-3-031-18784-1_7

Radio Transmitter - https://www.alamy.com/stock-photo-radio-transmitters-and-antennas-93650327.html?imageid=77526636-A13E-4051-81D6-015701E3556B&p=196573&pn=1&searchId=48043cf7c6bacb15fa86d8b005feb160&searchtype=0

Radio Reciver - AI Generated(Google Gemini)

Types of modulation - What is modulation page - https://byjus.com/jee/pulse-modulation/

Types of modulation: Image comparison - https://www.researchgate.net/figure/nput-signal-in-AM-and-FM-Adapted-from-5_fig8_322958535

 

*For the carrier wave we just intensly distorted the image of the message wave image.

 

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Information Citations

 

1. YouTube
   1. Modulation and Signals - What is Modulation ? Why Modulation is Required ? Types of Modulation Explained.
       
   2. EMS - Neil deGrasse Tyson Explains the Electromagnetic Spectrum
   3.  
2. Wikipedia
   1. Types of Modulation - Modulation - Wikipedia
   2.  
3. HowStuffWorks 
   1. Radio Waves -  How Radio Works | HowStuffWorks
   2.  
4. NASA
   1. EMS - Introduction to the Electromagnetic Spectrum - NASA Science
       

Electromagnetic waves -  Anatomy of an Electromagnetic Wave - NASA Science

Parents

Ossama Al-F.* (Jordan's Dad)

Ghena A. (Jordan's Mom)

Sandra S. (Eduardo's Mom)

Sergio S.** (Eduardo's Dad)

Us

Eduardo S.

Jordan Al-F.

All of our parents encouraged us on our journey to complete our project and offered us with supplies to work with.