Signal processing 101: The Magic Behind Modern Day Technology

A gentle introduction to signals

kipngeno koech
4 min readDec 23, 2024

Signals are the magic behind our digital lives, they power the technologies that connect us, entertain us and even that save lives. But what exactly is a signal?

Wi-Fi is signals, phone calls are signals, YouTube and Netflix are signals. Even the GPS guiding you on a road trip or the smart assistant playing your favorite music relies on signal. There is barely almost nothing we can’t link to signals. But what exactly is a signal? I dare ask again!

What is a signal?

According to oxford dictionary, a signal is a series of electrical waves that carry sounds, pictures or messages, for example to a radio, television or mobile phone.

In its basic form though is a way of sending information from one place to another. When you talk to someone, the sound of your voice becomes a signal. When you send an ‘hi’ to your friend, your phone converts this text into a digital 1 or 0 signals and sends it over the internet.

Signal Parameters

Signal parameters define the essential characteristics of a signal, particularly in the context of sinusoidal (sine wave) signals, which are common in electrical engineering. These are the common parameters:

  1. Amplitude
  2. Period
  3. Frequency
  4. Phase shift
  5. Angular frequency

Amplitude

This describes the maximum strength or intensity. This is the key factor that determines the quality and strength of a signal. In sound waves/signals it corresponds to the loudness. In light waves, the amplitude relates to brightness. In electrical signals, amplitude represents voltage or current levels.

Period

This is the amount of time it takes for a signal to complete one full cycle of its waveform. It is the reciprocal of the signal’s frequency and represents the duration of one repetition of the wave.

In communication systems, this determine how fast data can be transmitted.

Frequency

To a five year old child, I would say, frequency is how often something repeats. If we say a wave is 3hz, it means it repeats 3 times per second.

This refers to the number of cycles or oscillations of a periodic signal that occurs per unit time typically measured in Hz. Higher signals oscillate more rapidly and complete more cycles in the same amount of time.

Frequency spectrum

Every signal can be decomposed into a spectrum using tools like fourier transform. With these you can see the different frequency components that make up a signal.

Bandwidth is the range of frequencies within which a signal energy is concentrated.

A signal can be viewed as a composition of a number of sinusoidal signals with varied amplitude, frequency and phase. Any complex signal (even if it seems irregular or complicated) can be broken down into a sum of simpler sinusoidal signals. This concept is central to the Fourier Transform and the Fourier Series, which are mathematical techniques used in signal processing to analyze and represent signals in terms of their frequency components.

Time-domain and Frequency domain

There are two ways to represent a signal, time domain & frequency domain, and each provide different information about the signal

Time domain

This shows how the signal behaves over time. it focuses on the the signal amplitude change with respect to time. It displays the actual signal as it varies over time.

We normally use time domain when we need to show how the signal varies/evolves over time.

Frequency domain

It is shows how the signal is composed of various frequencies and their corresponding amplitudes. It focuses on how much energy is present at each frequency.

In the frequency domain, the signal is decomposed into frequency components.

conclusion

Signals are the unseen backbone of our connected world, powering advancements across diverse fields. Understanding signals and how they are processed offers valuable insights into the technologies that shape our daily lives. From streaming and navigation to communication and healthcare, signals are at the core of modern innovation, driving us toward a future filled with endless possibilities.

In future articles, we’ll explore signal processing in greater detail and uncover its role in shaping our everyday experiences.

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kipngeno koech
kipngeno koech

Written by kipngeno koech

You will find me here, lost in words, for it is my pen that listens and understands the depths of my soul.

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