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Introduction to Signals (1D, 2D and 3D Signals Explained)

Signals are information carriers that transmit data in communication, electronics, and control systems. They vary over time or space and have properties like amplitude, frequency, and phase.

Keywords: introduction to signals, 1D signals, 2D signals, 3D signals, signals and systems basics, continuous and discrete signals, GATE ECE signals

1D Signals

A 1D signal varies along a single variable (usually time).

  • ECG waveform: y = f(t), t = time, y = heart voltage
  • Audio from microphone: y = f(t), time-varying sound
1D Signal Example ECG waveform time vs amplitude

2D Signals

A 2D signal varies along two variables (space + space/time).

  • Grayscale image: y = f(x, k)
  • Temperature map on a plate: y = f(x, k)
  • Example - $ \text{rect}(x, y) = \begin{cases} 1, & \text{for } x < \frac{1}{2} \text{ and } y < \frac{1}{2} \\ 0, & \text{otherwise} \end{cases} $
2D plot of rect(x, y) function showing values 1 for 0 ≤ x, y < 0.5 and 0 otherwise

3D Signals

A 3D signal varies along three variables (2 space + time or 3D space).

  • Color video: y = f(x, y, t)
  • 3D medical scan: y = f(x, y, z)
  • Example: $$ \text{rect}(x, y, z) = \begin{cases} 1, & \text{if } \begin{aligned} 0 \le x < \tfrac{1}{2},\\ 0 \le y < \tfrac{1}{2},\\ 0 \le z < \tfrac{1}{2} \end{aligned} \\[2mm] 0, & \text{otherwise} \end{cases} $$
3D rectangular cube representing rect(x, y, z) function for 0 ≤ x, y, z < 0.5

Why Signals are Important?

  • Communication: Mobile, TV, Internet rely on signals
  • Control & Measurement: Sensors in drones/robots use signals
  • Medical: ECG, EEG for monitoring health
  • Entertainment: Music, video, movies are signals
  • Nature: Voice, birdsong, ocean waves—all signals
Application Signal Type Example
Medical 1D ECG
Image 2D Grayscale photo
Video 3D Color video clip

Discussion / Comments


Next: Elementary Signals Explained (With Graphs & Intuition)